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Aerospace, Volume 10, Issue 4 (April 2023) – 65 articles

Cover Story (view full-size image): Lighter-than-air vehicles are very interesting flying platforms which merge the high endurance of winged aircraft with the hovering ability and maneuverability of rotorcraft. A major shortcoming of airships comes with their envelope, often displays complex aerodynamic behavior, making flights disturbance-prone and hard to control. With the ambition to reduce complexity and weight by installing fewer components onboard, while simultaneously obtaining satisfying control and guidance performances, a purely thrust-based configuration with no thrust vectoring is studied in this work. Control for stabilization and guidance is applied to a candidate four-thruster configuration, which is designed by following an energy-optimal approach. Results are then checked with respect to a standard aerodynamic-controlled configuration, showing excellent results in a high-fidelity simulation environment. View this paper
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22 pages, 6955 KiB  
Article
Feasibility Study of the Bare-Photovoltaic-Tether Concept: Prototypes and Experimental Performance Evaluation of the Photovoltaic Tether Segment
by Leo Peiffer, Christian Perfler and Martin Tajmar
Aerospace 2023, 10(4), 386; https://doi.org/10.3390/aerospace10040386 - 21 Apr 2023
Viewed by 1616
Abstract
Consumable-free electron emitters are presently not feasible for autonomous tether-based deorbit devices such as E.T.PACK due to their power requirement. The bare-photovoltaic-tether (BPT) concept combines the bare tether electron collection with a tether segment, coated with thin film Copper Indium Gallium Selenide solar [...] Read more.
Consumable-free electron emitters are presently not feasible for autonomous tether-based deorbit devices such as E.T.PACK due to their power requirement. The bare-photovoltaic-tether (BPT) concept combines the bare tether electron collection with a tether segment, coated with thin film Copper Indium Gallium Selenide solar cells to harvest additional power for the cathodic contact, potentially enabling propellant-less operation. This thesis presents the first prototype of the photovoltaic tether segment, its architecture, its electrical characteristics, major challenges of the system and possible solutions. Photovoltaic tether segments of up to 3 m in length were manufactured, consisting of parallelized submodules of 25 cm in length. Due to space limitations, only the I-V-characteristics of these submodules were measured under a self-built Class BCA LED Solar-Simulator inside a vacuum chamber and at varying temperatures between −100 °C and 100 °C. In addition, the suitability of the concept for a low Earth orbit environment was assessed by performing atomic oxygen exposure tests using a microwave-based low pressure plasma atomic oxygen source. Based on the experimental data, a model is provided for predicting the performance of the photovoltaic segment in orbit, highlighting the main problems of the BPT: temperature, orientation and partial shading. Full article
(This article belongs to the Special Issue Advances in CubeSat Sails and Tethers)
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17 pages, 520 KiB  
Article
Sensitivity Analysis of a Hybrid MCDM Model for Sustainability Assessment—An Example from the Aviation Industry
by Dionysios N. Markatos, Sonia Malefaki and Spiros G. Pantelakis
Aerospace 2023, 10(4), 385; https://doi.org/10.3390/aerospace10040385 - 21 Apr 2023
Cited by 6 | Viewed by 1745
Abstract
When it comes to achieving sustainability and circular economy objectives, multi-criteria decision-making (MCDM) tools can be of aid in supporting decision-makers to reach a satisfying solution, especially when conflicting criteria are present. In a previous work of the authors, a hybrid MCDM tool [...] Read more.
When it comes to achieving sustainability and circular economy objectives, multi-criteria decision-making (MCDM) tools can be of aid in supporting decision-makers to reach a satisfying solution, especially when conflicting criteria are present. In a previous work of the authors, a hybrid MCDM tool was introduced to support the selection of sustainable materials in aviation. The reliability of an MCDM tool depends decisively on its robustness. Hence, in the present work, the robustness of the aforementioned tool has been assessed by conducting an extensive sensitivity analysis. To this end, the extent to which the results are affected by the normalization method involved in the proposed MCDM tool is examined. In addition, the sensitivity of the final output to the weights’ variation as well as to the data values variation has been investigated towards monitoring the stability of the tool in terms of the final ranking obtained. In order to carry out the analysis, a case study from the aviation industry has been considered. In the current study, carbon fiber reinforced plastics (CFRP) components, both virgin and recycled, are assessed and compared with regard to their sustainability by accounting for metrics linked to their whole lifecycle. The latter assessment also accounts for the impact of the fuel type utilized during the use phase of the components. The results show that the proposed tool provides an effective and robust method for the evaluation of the sustainability of aircraft components. Moreover, the present work can provide answers to questions raised concerning the adequacy of the CFRP recycled parts performance and their expected contribution towards sustainability and circular economy goals in aviation. Full article
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30 pages, 15866 KiB  
Article
Investigation of Very Large Eddy Simulation Method for Applications of Supersonic Turbulent Combustion
by Chong Yan, Yibing Xu, Ruizhe Cao and Ying Piao
Aerospace 2023, 10(4), 384; https://doi.org/10.3390/aerospace10040384 - 21 Apr 2023
Cited by 1 | Viewed by 1597
Abstract
The very large eddy simulation (VLES) method was investigated for supersonic reacting flows in the present work. The advantages and characteristics of the VLES model and the widely used improved delayed detached eddy simulation (IDDES) method were revealed through a supersonic ramped-cavity cold [...] Read more.
The very large eddy simulation (VLES) method was investigated for supersonic reacting flows in the present work. The advantages and characteristics of the VLES model and the widely used improved delayed detached eddy simulation (IDDES) method were revealed through a supersonic ramped-cavity cold flow. Compared to the IDDES model, the VLES model transformed from RANS mode to LES mode faster, resulting in a smaller gray region caused by the mode transition. However, the original volume-averaging truncation length scale could lead to poor predictions of the velocity profiles and wall pressure distribution. By introducing a hybrid truncation length scale combining the maximum grid length and the shear layer adaptive (SLA) length with different coefficients, the accuracy of the VLES method was significantly improved, and the issue of the low shear layer position was solved. Moreover, owing to the resolution control function, the VLES method could adaptively model more turbulent kinetic energy and maintain a good accuracy in a coarser mesh. Finally, the modified VLES method was applied in conjunction with a hybrid combustion model constructed by the partially stirred reactor (PaSR) model and the Ingenito supersonic combustion model (ISCM) in simulations of the supersonic flame in the DLR scramjet combustor. After introducing the correction of the molecular collision frequency by the ISCM, the results obtained by the hybrid combustion model were more consistent with the experimental results, especially for the time-averaging temperature profile in the ignition zone. Full article
(This article belongs to the Section Astronautics & Space Science)
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44 pages, 6971 KiB  
Article
Cost–Benefit Analysis of Investments in Air Traffic Management Infrastructures: A Behavioral Economics Approach
by Álvaro Rodríguez-Sanz and Luis Rubio Andrada
Aerospace 2023, 10(4), 383; https://doi.org/10.3390/aerospace10040383 - 20 Apr 2023
Cited by 1 | Viewed by 2726
Abstract
An important and challenging question for airport operators is the management of airport capacity and demand. Airport capacity depends on the available infrastructure, external factors, and operating procedures. Investments in Air Traffic Management (ATM) infrastructures mainly affect airside operations and include operational enhancements [...] Read more.
An important and challenging question for airport operators is the management of airport capacity and demand. Airport capacity depends on the available infrastructure, external factors, and operating procedures. Investments in Air Traffic Management (ATM) infrastructures mainly affect airside operations and include operational enhancements to improve the efficiency, reliability, and sustainability of airport operations. Therefore, they help increase capacity while limiting the impact on the airport infrastructure itself. By reviewing the neoclassical valuation principles for Cost–Benefit Analysis (CBA), we find that it does not consider relevant behavioral economic challenges to conventional analysis, particularly: failure of the expected utility hypotheses, dependence of valuations on reference points, and time inconsistency. These challenges are then incorporated through practical guidelines into the traditional welfare model to achieve a new methodology. We propose a novel CBA behavioral framework for investments in ATM infrastructures to help policy makers and airport operators when faced with a capacity development decision. This is complemented with a practical example to illustrate and test the applicability of the proposed model. The case study evaluates the deployment of Automatic Dependent Surveillance–Broadcast (ADS–B) as an investment aimed at improving ATM operational procedures in the airport environment by providing advanced ground surveillance data. This allows airport operators to discover the causes of taxi congestion and safety hotspots on the airport airside. The benefits of ADS–B are related to enhanced flight efficiency, reduced environmental impact, increased airport throughput, and improved operational predictability and flexibility, thus reducing waiting times. At the airport level, reducing the waiting times of aircraft on the ground would lead to a capacity release and a reduction in delays. The results show that, following a traditional CBA, the investment is clearly viable, with a strong economic return. Including behavioral notions allows us to propose a new evaluation framework that complements this conclusion with a model that also considers inconsistencies in time and risk perception. A positive Net Present Value can turn into a negative prospect valuation, if diminishing sensitivity and loss aversion are considered. This explains the reticent behavior of decision makers toward projects that require robust investments in the short-term, yet are slow to generate positive cash flows. Finally, we draw conclusions to inform policy makers about the effects of adopting a behavioral approach when evaluating ATM investments. Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management)
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30 pages, 20659 KiB  
Article
An Evaluation of Fixed-Wing Unmanned Aerial Vehicle Trends and Correlations with Respect to NATO Classification, Region, EIS Date and Operational Specifications
by Dimitrios Mitridis, Stavros Kapsalis, Dimitrios Terzis and Pericles Panagiotou
Aerospace 2023, 10(4), 382; https://doi.org/10.3390/aerospace10040382 - 20 Apr 2023
Cited by 3 | Viewed by 2079
Abstract
The current study provides a thorough analysis and evaluation of fixed-wing UAV correlations with respect to NATO classification, region of production, entry-into-service (EIS) date and other operational specifications. A set of 202 existing fixed-wing platforms is used to populate an in-house database. A [...] Read more.
The current study provides a thorough analysis and evaluation of fixed-wing UAV correlations with respect to NATO classification, region of production, entry-into-service (EIS) date and other operational specifications. A set of 202 existing fixed-wing platforms is used to populate an in-house database. A screening of the corresponding data is conducted using a correlations matrix, and a statistical analysis of the key UAV design parameters is, in turn, performed. The results are presented using a wide variety of charts and statistical coefficients, to provide as much information as possible for future UAV design and performance assessment studies. Correlations for each mission type are provided, followed by a detailed evaluation of the key design parameters and design ratios (wingspan, gross takeoff weight, empty weight, payload weight, endurance, and operational speeds) with respect to NATO classification and region of origin. These key parameters are then plotted as a function of EIS date for every NATO category to identify any underlying trends and, finally, the platforms are classified in regard to some qualitative attributes, such as mission type and low observability. The results suggest that the trendlines extracted for each category significantly deviate from the generic trends. Therefore, omitting the classification in terms of region, size and weight can lead to misleading outcomes and should be avoided. Another conclusion lies in the fact that, apart from the average trendline, the design engineers should also have an indication of the data variance, due to the high dispersion observed in the datasets of several design parameters. Full article
(This article belongs to the Section Aeronautics)
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14 pages, 15271 KiB  
Article
The Role of Additive Manufacturing in Reducing Demand Volatility in Aerospace: A Conceptual Framework
by Ageel Abdulaziz Alogla, Ateyah Alzahrani and Ahmad Alghamdi
Aerospace 2023, 10(4), 381; https://doi.org/10.3390/aerospace10040381 - 20 Apr 2023
Cited by 1 | Viewed by 2504
Abstract
The aerospace industry faces challenges in managing inventory effectively due to long product life cycles and unpredictable demand. Additive Manufacturing (AM) is a promising technology that enables the on-demand production of spare parts, potentially reducing inventory costs and improving supply chain efficiency. This [...] Read more.
The aerospace industry faces challenges in managing inventory effectively due to long product life cycles and unpredictable demand. Additive Manufacturing (AM) is a promising technology that enables the on-demand production of spare parts, potentially reducing inventory costs and improving supply chain efficiency. This paper proposes a novel conceptual framework for employing AM in the aerospace spare parts industry to isolate demand volatility. A conceptual approach is employed in this study, which involves a comprehensive literature review to identify the factors to consider when employing AM for spare parts and the methods for demand volatility isolation, followed by a structured framework development that outlines the decision-making steps for AM utilization based on the identified factors. The framework outlines a structured approach for using AM to produce spare parts and isolate demand volatility, which can help mitigate the impact of demand uncertainty on inventory management. The proposed approach provides a basis for future research and has the potential to transform how spare parts are produced and managed in the aerospace industry. Overall, this paper contributes to the emerging literature on AM in the aerospace industry by presenting a novel approach to improving inventory management and addressing demand uncertainty. Full article
(This article belongs to the Special Issue Metal Additive Manufacturing for Aerospace Applications)
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23 pages, 8384 KiB  
Article
A New Adaptive Control Algorithm of IGC System for Targets with Several Maneuvering Modes Based on GTSMC-DNN
by Kang Niu, Xu Bai, Xi Chen, Di Yang, Jiaxun Li and Jianqiao Yu
Aerospace 2023, 10(4), 380; https://doi.org/10.3390/aerospace10040380 - 19 Apr 2023
Viewed by 1199
Abstract
To improve the performance of intercepting a target with different maneuvering modes and changing the mode suddenly during the interception, a new adaptive control algorithm for the IGC (Integrated Guidance and Control) system is proposed, using the global terminal sliding mode control method [...] Read more.
To improve the performance of intercepting a target with different maneuvering modes and changing the mode suddenly during the interception, a new adaptive control algorithm for the IGC (Integrated Guidance and Control) system is proposed, using the global terminal sliding mode control method and a DNN (Deep Neural Network). Firstly, the missile-target problem is formulated and a new strict-feedback nonlinear IGC model with mismatched uncertainties is established. Secondly, the paper divides the IGC system into four subsystems, including a guidance subsystem, overload subsystem, attitude subsystem and the deep neural network subsystem. To transform the control signal between each subsystem and avoid the “differential explosion” problem, the paper defines the SOF (Second Order Filter). Thirdly, in combination with a deep neural network, a new modified global terminal sliding mode surface and the adaptive control law are designed. At last, using the Lyapunov theory, the stability of the IGC system is analyzed. Finally, to illustrate the effectiveness of the proposed algorithm, several simulation cases are given. The simulation results show the superiority of the proposed algorithm in adapting different maneuvering modes during the whole interception, improving the control performance and having a high interception accuracy. Full article
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19 pages, 5741 KiB  
Article
Attrition Risk and Aircraft Suitability Prediction in U.S. Navy Pilot Training Using Machine Learning
by Jubilee Prasad-Rao, Olivia J. Pinon Fischer, Neil C. Rowe, Jesse R. Williams, Tejas G. Puranik, Dimitri N. Mavris, Michael W. Natali, Mitchell J. Tindall and Beth W. Atkinson
Aerospace 2023, 10(4), 379; https://doi.org/10.3390/aerospace10040379 - 19 Apr 2023
Cited by 2 | Viewed by 3325
Abstract
The cost to train a basic qualified U.S. Navy fighter aircraft pilot is nearly USD 10 M. The training includes primary, intermediate, and advanced stages, with the advanced stage involving extensive flight training, and, thus, is very expensive as a result. Despite the [...] Read more.
The cost to train a basic qualified U.S. Navy fighter aircraft pilot is nearly USD 10 M. The training includes primary, intermediate, and advanced stages, with the advanced stage involving extensive flight training, and, thus, is very expensive as a result. Despite the screening tests in place and early-stage attrition, 4.5% of aviators undergo attrition in this most expensive stage. Key reasons for aviator attrition include poor flight performance, voluntary withdrawals, and medical reasons. The reduction in late-stage attrition offers several financial and operational benefits to the U.S. Navy. To that end, this research leverages feature extraction and machine learning techniques on the very sparse flight test grades of student aviators to identify those with a high risk of attrition early in training. Using about 10 years of historical U.S. Navy pilot training data, trained models accurately predicted 50% of attrition with a 4% false positive rate. Such models could help the U.S. Navy save nearly USD 20 M a year in attrition costs. In addition, machine learning models were trained to recommend a suitable training aircraft type for each student aviator. These capabilities could help better answer the need for pilots and reduce the time and cost to train them. Full article
(This article belongs to the Special Issue Machine Learning for Aeronautics)
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20 pages, 3297 KiB  
Article
Studies of Satellite Position Measurements of LEO CubeSat to Identify the Motion Mode Relative to Its Center of Mass
by Igor Belokonov, Ivan Timbai and Petr Nikolaev
Aerospace 2023, 10(4), 378; https://doi.org/10.3390/aerospace10040378 - 18 Apr 2023
Viewed by 1424
Abstract
This paper addresses the possibility of reconstructing motion relative to the center of mass of a low Earth orbit (LEO) nanosatellite of the CubeSat 3U standard using satellite position measurements (Two-Line Element Set (TLE)). This kind of task needs to be performed in [...] Read more.
This paper addresses the possibility of reconstructing motion relative to the center of mass of a low Earth orbit (LEO) nanosatellite of the CubeSat 3U standard using satellite position measurements (Two-Line Element Set (TLE)). This kind of task needs to be performed in the case where it is not possible to establish radio communication with the nanosatellite after it is launched into orbit. Therefore, it is important for the nanosatellite developers to develop some understanding of what is going on with the nanosatellite in order to be able to analyze the current situation after deployment. The study was carried out on the example of the aerodynamically stabilized SamSat-218D nanosatellite developed by the professors and students of Samara National Research University. SamSat-218D was launched into a near-circular orbit with an average altitude of 486 km on April 2016 during the first launch campaign from the Vostochny cosmodrome. Knowledge of CubeSat aerodynamics allows estimating the nature of its possible motion relative to the CubeSat center of mass by ballistic coefficient changes, evaluated with the use of satellite position measurements. The analysis showed that SamSat-218D performed spatial rotation with an angular velocity of more than two degree per second and had not stabilized aerodynamically by 2 March 2022, when it entered the atmosphere and was destroyed. Full article
(This article belongs to the Special Issue Optimal Spacecraft Planning and Control)
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23 pages, 10356 KiB  
Article
Towards Accurate Vortex Separation Simulations with RANS Using Improved k-kL Turbulence Model
by Erdem Dikbaş and Özgür Uğraş Baran
Aerospace 2023, 10(4), 377; https://doi.org/10.3390/aerospace10040377 - 18 Apr 2023
Cited by 1 | Viewed by 1200
Abstract
In this study, we present our improved RANS results of the missile aerodynamic flow computation involving leading edge vortex separation. We have used our in-house tailored version of the open source finite volume solver FlowPsi. An ongoing study in the NATO STO Applied [...] Read more.
In this study, we present our improved RANS results of the missile aerodynamic flow computation involving leading edge vortex separation. We have used our in-house tailored version of the open source finite volume solver FlowPsi. An ongoing study in the NATO STO Applied Vehicle Technologies Panel (AVT-316) has revealed that a highly maneuverable missile configuration (LK6E2) shows unusual rolling moment characteristics due to the vortex–surface interactions occurring during wing leading edge separation of vortices. We show the performance of the recently developed k-kL turbulence model for this test problem. This turbulence model is shown to have superior capabilities compared to other widely used turbulence models, such as Spalart–Allmaras and shear stress transport. With the k-kL turbulence model, it is possible to achieve more realistic computational results that agree better with the physical data. In addition, we propose improvements to this turbulence model to achieve even better predictions of rolling moment behavior. Modifications based on turbulence production terms in the k-kL turbulence model significantly improved the predicted rolling moment coefficient, in terms of accuracy and uncertainty. Full article
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22 pages, 10262 KiB  
Article
Structural Dynamic Characterization of a Modular Morphing Wing Exploiting Finite Elements and Taguchi Methodology
by Faisal Mahmood, Seyed M. Hashemi and Hekmat Alighanbari
Aerospace 2023, 10(4), 376; https://doi.org/10.3390/aerospace10040376 - 17 Apr 2023
Cited by 1 | Viewed by 1810
Abstract
Detrimental environmental impacts due to the increasing demands of the aviation industry have gained tremendous global attention. With a potential fuel saving, along with high aerodynamic performance and maneuverability during different phases of a flight, adaptable wing design has become a viable alternative [...] Read more.
Detrimental environmental impacts due to the increasing demands of the aviation industry have gained tremendous global attention. With a potential fuel saving, along with high aerodynamic performance and maneuverability during different phases of a flight, adaptable wing design has become a viable alternative to its fixed-shape counterpart. A morphing wing design embraces, and can respond accordingly to, most of the flight condition variations effectively and efficiently. Despite these prospects, morphing wing design comes with some challenges due to its inherent complexity caused by an increased number of degrees of freedom. With the availability of various morphing parameters, the vibration signature of a morphing wing design plays a vital role in terms of its structural as well as aeroelastic characteristics. In the present paper, the dynamic characteristics of a re-configurable modular morphing wing developed in-house by a research team at Toronto Metropolitan University are investigated. This modular morphing wing, developed based on the idea of a parallel robot, consists of a number of structural elements connected to each other and to the wing ribs through eyebolt joints. Timoshenko bending beam theories, in conjunction with finite element methodology, are exploited. The free vibration of un-morphed (original) and morphed configurations undergoing multiple levels of sweep and spanwise morphing is presented through a design of experiment methodology. Full article
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15 pages, 7253 KiB  
Article
The Impact of Temperature on the Surface Colour of Gas Turbine Blades Heated in the Presence of Kerosene
by Artur Kułaszka, Józef Błachnio and Henryk Borowczyk
Aerospace 2023, 10(4), 375; https://doi.org/10.3390/aerospace10040375 - 16 Apr 2023
Cited by 1 | Viewed by 1662
Abstract
The reliability and operational safety of an aircraft engine gas turbine are extremely important in terms of its operation. In the course of operation, these turbines undergo complex thermal, mechanical, aerodynamic, and chemical exhaust gas loads. Due to such a load, particularly acting [...] Read more.
The reliability and operational safety of an aircraft engine gas turbine are extremely important in terms of its operation. In the course of operation, these turbines undergo complex thermal, mechanical, aerodynamic, and chemical exhaust gas loads. Due to such a load, particularly acting upon the rotor blades, they undergo various damages. Therefore, the maintenance processes continuously strive for enhancing diagnostic methods in order to improve the sensitivity and reliability of damage identification. The basic diagnostic method is a visual one, supported by an optoelectronic device. It only enables determining the fact of a damage, e.g., mechanical, thermal, or chemical. The turbine blade material degradation degree is very difficult to assess in a nondestructive manner in the course of engine operation. No objective, and yet nondestructive, diagnostic method enabling the assessment of blade alloy structural changes has been developed so far. Therefore, a thesis was put forward that it was possible to apply the visual method and correlate its results with the results of gas turbine blade microstructural change tests, which would enable detecting early damage phases and assessing their fitnesses. The tests were conducted with the laboratory method. The authors received new blades of the SO-3 aircraft gas turbine engine made of the EI-867 WD alloy and then subjected them to heating in a laboratory furnace, over a temperature range of T = 1123–1523 K, in increments of 100 K. Cooling took place in the furnace. Prior to and after heating, the blades were subjected to visual testing. Blade surface colour is a diagnostic symptom which indicates a change in the blades’ technical condition. The images were analysed using software developed for the MATLAB environment. The extracted surface image features are presented in the form of brightness distribution histograms for individual colour components RGB(red, green, and blue) and grayscale Sz. Histogram parameters — average value, standard deviation, maximum value and its position — were calculated. In consequence of conducted studies, it was concluded that an increase in blade heating temperature entailed changes in individual RGB colours and the grayscale (Sz) of their surface images, which indicate the overheating intensity. Full article
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24 pages, 4383 KiB  
Article
Preliminary Aero-Elastic Optimization of a Twin-Aisle Long-Haul Aircraft with Increased Aspect Ratio
by Francesco Toffol and Sergio Ricci
Aerospace 2023, 10(4), 374; https://doi.org/10.3390/aerospace10040374 - 15 Apr 2023
Cited by 6 | Viewed by 2310
Abstract
This paper presents a preliminary study on the improvement of the fuel efficiency of a civil transport aircraft, focusing on the aero-elastic optimization of an increased aspect ratio wingbox. The wing is stretched, increasing its aspect ratio, and a trade-off between the improved [...] Read more.
This paper presents a preliminary study on the improvement of the fuel efficiency of a civil transport aircraft, focusing on the aero-elastic optimization of an increased aspect ratio wingbox. The wing is stretched, increasing its aspect ratio, and a trade-off between the improved aerodynamic efficiency and the structural mass identifies an optimal aspect ratio for such aircraft. The aeroelastic optimization is performed with NeOPT, a structural optimizer for conceptual and preliminary design phases. The analysis considers different materials and structural solutions for the wingbox and tackles aeroelastic constraints, such as flutter and aileron efficiency, from the preliminary design phases. The fuel consumption of the sized aircraft is evaluated with a simplified approach that provides an indication of the fuel efficiency. The results show how a composite wing with increased aspect ratio can save up to 6.9% of fuel burnt with respect to the baseline aluminum wing. The results are extended at fleet level, achieving a 2-million-ton cut in CO2 emissions and a saving of USD 1.28 million on fuel-related costs. Full article
(This article belongs to the Special Issue Aircraft Design (SI-4/2022))
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17 pages, 3746 KiB  
Article
Using Energy Particle Detection Technology on the Tiangong’s Space Station’s Wentian Laboratory Cabin Module
by Guohong Shen, Shenyi Zhang, Xianguo Zhang, Huanxin Zhang, Bin Yuan, Donghui Hou, Chunqin Wang, Zida Quan, Zhe Yang and Yueqiang Sun
Aerospace 2023, 10(4), 373; https://doi.org/10.3390/aerospace10040373 - 14 Apr 2023
Cited by 2 | Viewed by 1411
Abstract
To conduct real-time monitoring of the particle radiation environment in the orbit of the Tiangong space station, the installation of an energy particle detector operating on the outside of Wentian laboratory cabin module is proposed. Monitoring the energy, flux, and direction of high-energy [...] Read more.
To conduct real-time monitoring of the particle radiation environment in the orbit of the Tiangong space station, the installation of an energy particle detector operating on the outside of Wentian laboratory cabin module is proposed. Monitoring the energy, flux, and direction of high-energy protons, electrons, heavy ions, and neutrons in orbital space, as well as the LET spectrum and radiation dose rate generated by them, provides an important basis for studying the mechanism of the space environment that causes harm to space stations and astronauts. It also provides the necessary space environment parameters for the scientific experiment instruments on the space station. During its ground development process, the detector was verified by various calibration methods such as standard radioactive sources, equivalent signal generators, and particle accelerators. The results show that the detector can realize discrimination of particle ingredients (electrons, protons, heavy ions, and neutrons). Meanwhile, the measurement indexes can also realize target requirements, namely, from lower limit of 20 keV for medium-energy electrons and protons to heavy ion GeV, 0.025 eV~100 MeV for neutrons, and 0.233~17,475 keV/μm for the LET spectrum and 0.1~1000 mGy/day for the dose rate produced. The measurement precisions of all indexes are better than approximately 16%. Full article
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20 pages, 12021 KiB  
Article
Numerical Study of Nonadiabatic Wall Effects on Aerodynamic Characteristics of CHN-T1 Standard Model
by Xiaobing Wang, Junqiang Wu, Jianzhong Chen, Yuping Li, Zhongliang Zhao, Guangyuan Liu, Yang Tao and Neng Xiong
Aerospace 2023, 10(4), 372; https://doi.org/10.3390/aerospace10040372 - 14 Apr 2023
Cited by 2 | Viewed by 1192
Abstract
Cryogenic wind tunnels provide the for possibility aerodynamic tests to take place over high Reynolds numbers by operating at a low gas temperature to meet the real flight simulation requirements, especially for state-of-the-art large transport aircrafts. However, undesirable temperature gradients between the test [...] Read more.
Cryogenic wind tunnels provide the for possibility aerodynamic tests to take place over high Reynolds numbers by operating at a low gas temperature to meet the real flight simulation requirements, especially for state-of-the-art large transport aircrafts. However, undesirable temperature gradients between the test model and the surroundings will be caused by the thermal non-equilibrium, changing the boundary layer characteristics and resulting in test errors. To study the nonadiabatic wall effects on the aerodynamic characteristics of the model in cryogenic wind tunnels, a numerical study was carried out for the CHN-T1 standard model under different wall temperature gradients. A code with a finite volume method and γ-Reθt transition model were used. The analysis concluded that the change in wall temperature significantly affects the surface pressure distribution, transition position and skin-friction coefficient of the model, thus varying the lift and drag coefficients of the aircraft. The influences on the flow characteristics of both laminar and turbulent boundary layers by the wall temperature gradient were also investigated. Full article
(This article belongs to the Section Aeronautics)
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22 pages, 14479 KiB  
Article
Short-Arc Horizon-Based Optical Navigation by Total Least-Squares Estimation
by Huajian Deng, Hao Wang, Yang Liu and Zhonghe Jin
Aerospace 2023, 10(4), 371; https://doi.org/10.3390/aerospace10040371 - 13 Apr 2023
Viewed by 1394
Abstract
Horizon-based optical navigation (OPNAV) is an attractive solution for deep space exploration missions, with strong autonomy and high accuracy. In some scenarios, especially those with large variations in spacecraft distance from celestial bodies, the visible horizon arc could be very short. In this [...] Read more.
Horizon-based optical navigation (OPNAV) is an attractive solution for deep space exploration missions, with strong autonomy and high accuracy. In some scenarios, especially those with large variations in spacecraft distance from celestial bodies, the visible horizon arc could be very short. In this case, the traditional Christian–Robinson algorithm with least-squares (LS) estimation is inappropriate and would introduce a large mean residual that can be even larger than the standard deviation (STD). To solve this problem, a simplified measurement covariance model was proposed by analyzing the propagation of measurement errors. Then, an unbiased solution with the element-wise total least-squares (EW-TLS) algorithm was developed in which the measurement equation and the covariance of each measurement are fully considered. To further simplify this problem, an approximate generalized total least-squares algorithm (AG-TLS) was then proposed, which achieves a non-iterative solution by using approximate measurement covariances. The covariance analysis and numerical simulations show that the proposed algorithms have impressive advantages in the short-arc horizon scenario, for the mean residuals are always close to zero. Compared with the EW-TLS algorithm, the AG-TLS algorithm trades a negligible accuracy loss for a huge reduction in execution time and achieves a computing speed comparable to the traditional algorithm. Furthermore, a simulated navigation scenario reveals that a short-arc horizon can provide reliable position estimates for planetary exploration missions. Full article
(This article belongs to the Special Issue Advanced Spacecraft/Satellite Technologies)
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20 pages, 2914 KiB  
Article
Satellite Attitude Determination Using ADS-B Receiver and MEMS Gyro
by Zhiyong Liu, Kaixing Zhou and Xiucong Sun
Aerospace 2023, 10(4), 370; https://doi.org/10.3390/aerospace10040370 - 12 Apr 2023
Cited by 3 | Viewed by 1592
Abstract
Automatic dependent surveillance-broadcast (ADS-B) is a very important communication and surveillance technology in air traffic control (ATC). In the future, more and more satellites will carry out ADS-B technology to perform a global coverage. In order to make full use of the resources [...] Read more.
Automatic dependent surveillance-broadcast (ADS-B) is a very important communication and surveillance technology in air traffic control (ATC). In the future, more and more satellites will carry out ADS-B technology to perform a global coverage. In order to make full use of the resources in the satellite, this paper proposes a solution for satellite three-axis attitude determination using the ADS-B receiver. The principle of ADS-B-based attitude determination is presented first. On this basis, ADS-B-based methods are employed to solve the problem. To achieve a higher attitude determination precision, gyro is combined with the ADS-B receiver using a multiplicative extended Kalman filter (MEKF). Finally, a simulation is carried out and the result is presented. Full article
(This article belongs to the Special Issue Satellite Attitude Determination and Control)
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12 pages, 4423 KiB  
Article
Effective Distance for Vortex Generators in High Subsonic Flows
by Ping-Han Chung, Yi-Xuan Huang, Kung-Ming Chung, Chih-Yung Huang and Sergey Isaev
Aerospace 2023, 10(4), 369; https://doi.org/10.3390/aerospace10040369 - 12 Apr 2023
Cited by 1 | Viewed by 1868
Abstract
Vortex generators (VGs) are a passive method by which to alleviate boundary layer separation (BLS). The device-induced streamwise vortices propagate downstream. There is then lift-off from the surface and the vortex decays. The effectiveness of VGs depends on their geometrical configuration, spacing, and [...] Read more.
Vortex generators (VGs) are a passive method by which to alleviate boundary layer separation (BLS). The device-induced streamwise vortices propagate downstream. There is then lift-off from the surface and the vortex decays. The effectiveness of VGs depends on their geometrical configuration, spacing, and flow characteristics. In a high-speed flow regime, the VGs must be properly positioned upstream of the BLS region. Measurements using discrete pressure taps and pressure-sensitive paint (PSP) show that there is an increase in the upstream surface pressure and the downstream favorable pressure gradient. The effective distance for a flat plate in the presence of three VG configurations is determined, as is the height of the device (conventional and micro VGs). Full article
(This article belongs to the Special Issue Flow Control and Drag Reduction)
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15 pages, 6299 KiB  
Article
Simulation of Drilling Temperature Rise in Frozen Soil of Lunar Polar Region Based on Discrete Element Theory
by Jinsheng Cui, Le Kui, Weiwei Zhang, Deming Zhao and Jiaqing Chang
Aerospace 2023, 10(4), 368; https://doi.org/10.3390/aerospace10040368 - 11 Apr 2023
Cited by 2 | Viewed by 1348
Abstract
As the frozen soil in the South Pole region of the Moon is an important water resource, the operation of drilling and retrieving samples of the frozen soil in this region will be a crucial task for us to accomplish in future deep-space [...] Read more.
As the frozen soil in the South Pole region of the Moon is an important water resource, the operation of drilling and retrieving samples of the frozen soil in this region will be a crucial task for us to accomplish in future deep-space exploration. Thus, this paper investigated the effects of the increasing temperature and heat transfer between the drilling tools and the simulated lunar soil to minimize the degradation of the frozen soil samples during drilling due to the increased temperature. Specifically, the discrete element method was adopted and the heat transfer parameters of the discrete element particles were calibrated based on the equivalent heat transfer of the particle system. Moreover, a lunar soil particle system was developed for the simulations. Under the current working conditions with reasonable parameters, the maximum increase in the drill bit temperature was about 60 °C. Overall, the simulation results were consistent with the experimental results, and further analysis revealed that the flow of lunar soil can effectively take away thermal, which is also one of the reasons why the simulated lunar soil particles are in a high-temperature state at the front of the drilling tool. Full article
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23 pages, 7876 KiB  
Article
Coupled Thermo-Mechanical Numerical Modeling of CFRP Panel under High-Velocity Impact
by Alessandro Polla, Giacomo Frulla, Enrico Cestino, Raj Das and Pier Marzocca
Aerospace 2023, 10(4), 367; https://doi.org/10.3390/aerospace10040367 - 10 Apr 2023
Cited by 3 | Viewed by 2009
Abstract
Advanced composites have a brittle nature making them highly susceptible to failure and propagation under impact loading conditions. Appropriate modeling techniques to accurately simulate these conditions are required. This study presents and examines a coupled thermo-mechanical modeling technique and its associated numerical simulations [...] Read more.
Advanced composites have a brittle nature making them highly susceptible to failure and propagation under impact loading conditions. Appropriate modeling techniques to accurately simulate these conditions are required. This study presents and examines a coupled thermo-mechanical modeling technique and its associated numerical simulations for analyzing carbon fiber-reinforced composite panels subjected to high-velocity impact. The essential numerical parameters necessary to accurately simulate the selected configuration are determined through a physical-based approach, which has not been previously reported. By following the proposed framework, the conventional trial-and-error calibration process that relies on an extensive testing campaign is minimized. A stacked shell-cohesive methodology has been applied to T800/F3900 unidirectional carbon fiber/epoxy composite panel with 16 plies in a quasi-isotropic layup configuration [(0/90/45/-45)2]s. The flat composite panel was manufactured according to ASTM D8010 standards. Both failure condition and progressive damage analysis have been explored and discussed in comparison with numerical and experimental test cases available in the open literature. Thermal effects on the mechanical performance of composite targets are also discussed based on the application of the constitutive transient thermal coupling method available in LS-DYNA®. The contact heat generated by the conversion of impact-induced damage and the kinetic energy of the projectile is also evaluated and analyzed. New observations regarding modeling techniques, energy transfer, and damage mechanisms in target plates are offered. Additionally, findings related to changes in material characteristics resulting from heat transfer are discussed. Full article
(This article belongs to the Section Aeronautics)
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19 pages, 7595 KiB  
Article
A B5G Non-Terrestrial-Network (NTN) and Hybird Constellation Based Data Collection System (DCS)
by Yifei Jiang, Wanxia He, Wenzheng Liu, Shufan Wu, Xiao Wei and Qiankun Mo
Aerospace 2023, 10(4), 366; https://doi.org/10.3390/aerospace10040366 - 10 Apr 2023
Cited by 3 | Viewed by 2068
Abstract
In beyond 5G (B5G) non-terrestrial network (NTN) systems, satellite technologies play an important role. Especially for data collection systems (DCS), low-earth orbit satellites have many advantages. Such as global coverage, low latency, and high efficiency. As a miniaturization technology, CubeSat has attracted extensive [...] Read more.
In beyond 5G (B5G) non-terrestrial network (NTN) systems, satellite technologies play an important role. Especially for data collection systems (DCS), low-earth orbit satellites have many advantages. Such as global coverage, low latency, and high efficiency. As a miniaturization technology, CubeSat has attracted extensive attention from a large number of scholars. Satellite constellations can coordinate for distributed tasks. This paper proposes a B5G NTN-based data collection system. A CubeSat constellation achieves global coverage as the basic space platform for DCS. The 5G terrestrial network is used as the data bearer network of the gateway station. A traffic load balance strategy is proposed to optimize the system’s efficiency. As a unified hardware platform, software-defined radio (SDR) is compatible with various sensor data models. Finally, the design was verified by a series of experiments. Full article
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25 pages, 6597 KiB  
Article
Flight Control Law for Stabilizing Transient Response of the Aircraft during Gun Firing
by Chang-ho Ji, Chongsup Kim and Byoung Soo Kim
Aerospace 2023, 10(4), 365; https://doi.org/10.3390/aerospace10040365 - 10 Apr 2023
Viewed by 2192
Abstract
Highly maneuverable fighter aircraft are equipped with various weapons including a gun firing system for successful air-to-air and air-to-ground missions. In the gun firing system, the muzzle is usually positioned at an offset from the centerline of the aircraft to facilitate maintainability and [...] Read more.
Highly maneuverable fighter aircraft are equipped with various weapons including a gun firing system for successful air-to-air and air-to-ground missions. In the gun firing system, the muzzle is usually positioned at an offset from the centerline of the aircraft to facilitate maintainability and accessibility on the ground, to ensure the pilot’s visibility, and to avoid vibrations. However, this mounting position causes the repulsive force for gun firing to generate a moment around the center of gravity and distorts the aircraft’s attitude, degrading the accuracy of the target point. In this paper, we propose the application of an additional augmentation control method, as a hybrid INDI control, that combines model- and sensor-based incremental nonlinear dynamic inversion (INDI) controls to minimize the maximum overshoot of transient response of the aircraft during gun firing. As a result of the frequency- and time-domain evaluation, the additional augmentation control can effectively reduce the transient response during gun firing. In addition, this control method is more robust against uncertainties, and its structure is simple compared to the conventional open-loop type gun compensation control since it does not require any gain scheduling according to flight conditions. Full article
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23 pages, 10454 KiB  
Article
Optimal Design and Analysis of a High-Load Supersonic Compressor Based on a Surrogate Model
by Shiji Zhou, Shengfeng Zhao, Chuangxin Zhou, Yunfeng Wu, Hang Yuan and Xingen Lu
Aerospace 2023, 10(4), 364; https://doi.org/10.3390/aerospace10040364 - 10 Apr 2023
Cited by 2 | Viewed by 1484
Abstract
To explore the internal flow mechanism and improve the performance of a supersonic compressor, an efficient global optimization design method was developed for an axial flow compressor and applied in the optimization design of a prototype supersonic compressor. Based on the multiple circular [...] Read more.
To explore the internal flow mechanism and improve the performance of a supersonic compressor, an efficient global optimization design method was developed for an axial flow compressor and applied in the optimization design of a prototype supersonic compressor. Based on the multiple circular arc (MCA) blade parameters, the method can be used to parameterize the elementary stage of the blade. The optimized solution is obtained by changing the elementary stage and stacking lines of the blade during the optimization process. It has the advantages of fewer optimization variables, strong physical intuition, and a smooth surface. The optimization results show that a change in the rotor blade shape parameters has a significant effect on the compressor efficiency under design conditions, while a change in the skewed-swept parameters of the stator is the main factor that improves the compressor’s performance under near-stall conditions. Further numerical results show that the optimized rotor changes the form of the shock, weakens the degree of shock boundary layer interference, inhibits the radial migration flow of the supersonic rotor, reduces the loss of the rotor blade top, and improves the performance of the compressor under design conditions. The stator’s optimization restrains the generation of a concentrated shedding vortex at the root of the blades and greatly improves the stall margin of the compressor. Finally, the total pressure ratio and flow rate are less than 1% of the values based on the prototype operating conditions, the design mass flow of the optimized high-load supersonic compressor is increased by 0.25%, the isentropic efficiency is increased by 1.05%, and the stall margin is enhanced by 3.5%, thus verifying the effectiveness of the optimization method. Full article
(This article belongs to the Special Issue Machine Learning for Aeronautics)
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22 pages, 10672 KiB  
Article
Study of Plasma-Based Vortex Generator in Supersonic Turbulent Boundary Layer
by Pavel Polivanov, Oleg Vishnyakov and Andrey Sidorenko
Aerospace 2023, 10(4), 363; https://doi.org/10.3390/aerospace10040363 - 10 Apr 2023
Cited by 4 | Viewed by 1655
Abstract
The problem of flow control under conditions of a turbulent boundary layer at transonic and supersonic free-stream velocities is considered. Such flows are integral components of the flight process and exert significant effects on the flow around both the aerodynamic object as a [...] Read more.
The problem of flow control under conditions of a turbulent boundary layer at transonic and supersonic free-stream velocities is considered. Such flows are integral components of the flight process and exert significant effects on the flow around both the aerodynamic object as a whole and its individual elements. The present paper describes investigations of a combined control device (“plasma wedge”), which is a wedge mounted along the flow with the energy supply at one side of the wedge owing to a spark discharge. The strategy of flow control by this device is based on increasing the momentum in the boundary layer, which enhances its resistance to the adverse pressure gradient and, as a consequence, its resistance to flow separation further downstream. The study includes experimental and computational aspects. The examined flow evolves on a rectangular flat plate with a sharp leading edge at the free-stream Mach number M = 1.45 and unit Reynolds numbers Re1 = 11.5·106 1/m. The experiments are performed to study the velocity fields and the pressure distribution in the wake behind the actuator. The results show that a streamwise vortex is formed in the wake behind the actuator when the discharge is initiated. Reasonable agreement of the experimental data with numerical simulations allows one to conclude that the Reynolds-averaged Navier–Stokes equations are suitable tools for solving the problem considered. Full article
(This article belongs to the Section Aeronautics)
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24 pages, 5182 KiB  
Article
Effect of Structural Materials on Monopropellant Thruster Propulsion Performance in Micro Scale
by Jeongmoo Huh and Ki Sun Park
Aerospace 2023, 10(4), 362; https://doi.org/10.3390/aerospace10040362 - 9 Apr 2023
Cited by 4 | Viewed by 1493
Abstract
This paper reports on the effect of structural materials on heat loss-associated propulsion performance degradation of monopropellant thrusters in the micro scale. In order to address the effect of fabrication materials on heat loss, propellant flow characteristics, and propulsion performance, a conjugate heat [...] Read more.
This paper reports on the effect of structural materials on heat loss-associated propulsion performance degradation of monopropellant thrusters in the micro scale. In order to address the effect of fabrication materials on heat loss, propellant flow characteristics, and propulsion performance, a conjugate heat transfer numerical study has been conducted considering several practical substrate candidates for microthrusters. The results were analyzed with respect to the thermal diffusivity of the materials, which revealed different propulsion performance characteristics and inner nozzle flow characteristics due to varying amounts of heat loss, depending on the microfabrication materials used and propellant enthalpies. Regardless of propellant enthalpies, however, there was a dramatic degradation in the amount of the thrust produced with respect to thermal diffusivity, particularly in the range of low thermal diffusivity. Glass, among the material types compatible with fabrication processes in regard to microthrusters, exhibited a 4% degradation in thrust performance for the 50 mN class microthruster considered, with the least degradation, while copper, with 7% degradation, exhibited the greatest amount of degradation among the materials considered. With varying chamber pressure and Mach number at the nozzle exit depending on structural materials, the results also indicated the necessity of heat loss consideration in a microthruster design process. Full article
(This article belongs to the Section Astronautics & Space Science)
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14 pages, 6042 KiB  
Article
Experimental Study of the Bending Behaviour of the Neovius Porous Structure Made Additively from Aluminium Alloy
by Katarina Monkova, Peter Pavol Monka, Milan Žaludek, Pavel Beňo, Romana Hricová and Anna Šmeringaiová
Aerospace 2023, 10(4), 361; https://doi.org/10.3390/aerospace10040361 - 9 Apr 2023
Cited by 6 | Viewed by 1564
Abstract
Porous materials bring components not only direct advantages in the form of lightening of constructions, saving of production materials, or improvement of physical properties, but also secondary advantages, which are manifested as a result of their daily use, e.g., in aviation and the [...] Read more.
Porous materials bring components not only direct advantages in the form of lightening of constructions, saving of production materials, or improvement of physical properties, but also secondary advantages, which are manifested as a result of their daily use, e.g., in aviation and the automotive industry, which is manifested in saving fuel and, thus, environmental protection. The aim of this article is to examine the influence of the volume ratio of a complex porous structure, the so-called Neovius, on bending properties. Samples with five different relative weights of 15, 20, 25, 30, and 50% (±1%) were fabricated from AlSi10Mg aluminum alloy by Direct Laser Metal Sintering (DLMS) technology. A three-point bending test until specimen failure was performed at ambient temperature on a Zwick/Roell 1456 universal testing machine. The dependences of the bending forces on the deflection were recorded. The maximum stresses, energy absorption, and ductility indexes were calculated to compare the bending behavior of beams filled with this type of complex cellular structure. The results showed that Neovius, with a relative weight of 50%, was much more brittle compared to the other samples, while the Neovius structure, with a relative weight of 30%, appeared to be the most suitable structure for bent components among those tested. This study is a contribution not only to the development of the space and aviation industry but also to the expansion of the knowledge base in the field of material sciences. This know-how can also provide a basis for defining boundary conditions in the simulation of behavior and numerical analyses of 3D-printed lightweight components. Full article
(This article belongs to the Special Issue Metal Additive Manufacturing for Aerospace Applications)
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17 pages, 6329 KiB  
Article
A Numerical Study on the Flap Side-Edge Noise Reduction Using Passive Blowing Air Concept
by Yingzhe Zhang, Baohong Bai, Dakai Lin and Peiqing Liu
Aerospace 2023, 10(4), 360; https://doi.org/10.3390/aerospace10040360 - 7 Apr 2023
Cited by 2 | Viewed by 1529
Abstract
The flap side-edge is a vital contributor to airframe noise. In this study, we propose a novel flap side-edge noise reduction method based on the concept of active blowing air. A long slot is opened from the flap’s lower surface to the tip [...] Read more.
The flap side-edge is a vital contributor to airframe noise. In this study, we propose a novel flap side-edge noise reduction method based on the concept of active blowing air. A long slot is opened from the flap’s lower surface to the tip surface to induce a secondary jet flow, which is driven by the local pressure difference between the flap’s lower surface and the tip surface. The unsteady flow field around the flap side-edge was computed by the lattice Boltzmann solver PowerFLOW, and the far-field noise was predicted by the FW-H equation. It is demonstrated that the dominant features of the flap side-edge flow are the double vortex structures, and the new passive blowing air reduction method can achieve about 3.3 dB noise reduction. Moreover, the underlying noise reduction mechanism has been analyzed and revealed. It is shown that the secondary jet flow from the long slot on the flap side-edge would dissipate the flap side-edge vortex and displace the flap side-edge vortical structure away from the flap surface, thus resulting in a decrease in the pressure fluctuations on the flap side-edge surface. As a result, the flap side-edge noise was reduced. In contrast to the current active air blowing technique, the newly proposed blowing air technique is passive and quite simple and does not require an extra air source or control system. This novel flap side-edge noise reduction technology provides a new flow control strategy and noise reduction methodology and can be further optimized. Full article
(This article belongs to the Special Issue Aeroacoustics and Noise Mitigation)
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24 pages, 5776 KiB  
Article
Numerical Analysis of the Effects of Grooved Stator Vanes in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow
by José Galindo, Andrés Tiseira, Roberto Navarro, Lukas Benjamin Inhestern and Juan David Echavarría
Aerospace 2023, 10(4), 359; https://doi.org/10.3390/aerospace10040359 - 5 Apr 2023
Viewed by 1476
Abstract
The flow through the stator vanes of a variable geometry turbocharger turbine can reach supersonic conditions and generates a shock wave on the stator vanes, which has a potential impact on the flow loss as well as on unsteady aerodynamic interaction. The shock [...] Read more.
The flow through the stator vanes of a variable geometry turbocharger turbine can reach supersonic conditions and generates a shock wave on the stator vanes, which has a potential impact on the flow loss as well as on unsteady aerodynamic interaction. The shock wave causes a sudden increase in pressure and can lead to boundary separation and strong excitation force, besides pressure fluctuation in the rotor blades. Thus, in this study, the flat surface of the vanes of a commercial variable geometry turbocharger turbine has been modified to analyze the effects of two grooved surfaces configuration using CFD simulations. The results reveal that the grooves change the turbine efficiency, especially at higher speed, where the increase in the efficiency is between 2% and 6% points. Additionally, the load fluctuation around the rotor leading edge can be reduced and minimize the factors that compromise the integrity of the turbine. Furthermore, the grooves reduce the supersonic pocket developed on the suction side of the vane and diminish the shock wake intensity. Evaluating the effectiveness of the available energy usage in the turbine, on the one hand, at lower speed, the fraction of energy at the inlet destinated to produce power does not change significantly with a grooved surface on the stator vanes. On the other hand, at higher speed and higher pressure ratio with 5 grooves occurs the most effective approach of the maximum energy. Full article
(This article belongs to the Section Aeronautics)
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30 pages, 11096 KiB  
Review
Deep Learning in Air Traffic Management (ATM): A Survey on Applications, Opportunities, and Open Challenges
by Euclides Carlos Pinto Neto, Derick Moreira Baum, Jorge Rady de Almeida, Jr., João Batista Camargo, Jr. and Paulo Sergio Cugnasca
Aerospace 2023, 10(4), 358; https://doi.org/10.3390/aerospace10040358 - 4 Apr 2023
Cited by 6 | Viewed by 5352
Abstract
Currently, the increasing number of daily flights emphasizes the importance of air transportation. Furthermore, Air Traffic Management (ATM) enables air carriers to operate safely and efficiently through the multiple services provided. Advanced analytic solutions have demonstrated the potential to solve complex problems in [...] Read more.
Currently, the increasing number of daily flights emphasizes the importance of air transportation. Furthermore, Air Traffic Management (ATM) enables air carriers to operate safely and efficiently through the multiple services provided. Advanced analytic solutions have demonstrated the potential to solve complex problems in several domains, and Deep Learning (DL) has attracted attention due to its impressive results and disruptive capabilities. The adoption of DL models in ATM solutions enables new cognitive services that have never been considered before. The main goal of this research is to present a comprehensive review of state-of-the-art Deep Learning (DL) solutions for Air Traffic Management (ATM). This review focuses on describing applications, identifying opportunities, and highlighting open challenges to foster the evolution of ATM systems. To accomplish this, we discuss the fundamental topics of DL and ATM and categorize the contributions based on different approaches. First, works are grouped based on the DL approach adopted. Then, future directions are identified based on the ATM solution area. Finally, open challenges are listed for both DL applications and ATM solutions. This article aims to support the community by identifying research problems to be faced in the future. Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management)
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13 pages, 3347 KiB  
Article
A Novel Fault-Tolerant Air Traffic Management Methodology Using Autoencoder and P2P Blockchain Consensus Protocol
by Seyed Mohammad Hashemi, Seyed Ali Hashemi, Ruxandra Mihaela Botez and Georges Ghazi
Aerospace 2023, 10(4), 357; https://doi.org/10.3390/aerospace10040357 - 4 Apr 2023
Cited by 6 | Viewed by 1446
Abstract
This paper presents a methodology for designing a highly reliable Air Traffic Management and Control (ATMC) methodology using Neural Networks and Peer-to-Peer (P2P) blockchain. A novel data-driven algorithm was designed for Aircraft Trajectory Prediction (ATP) based on an Autoencoder architecture. The Autoencoder was [...] Read more.
This paper presents a methodology for designing a highly reliable Air Traffic Management and Control (ATMC) methodology using Neural Networks and Peer-to-Peer (P2P) blockchain. A novel data-driven algorithm was designed for Aircraft Trajectory Prediction (ATP) based on an Autoencoder architecture. The Autoencoder was considered in this study due to its excellent fault-tolerant ability when the input data provided by the GPS is deficient. After conflict detection, P2P blockchain was used for securely decentralized decision-making. A meta-controller composed of this Autoencoder, and P2P blockchain performed the ATMC task very well. A comprehensive database of trajectories constructed using our UAS-S4 Ehécatl was used for algorithms validation. The accuracy of the ATP was evaluated for a variety of data failures, and the high-performance index confirmed the excellent efficiency of the autoencoder. Aircraft were considered in several local encounter scenarios, and their trajectories were securely managed and controlled using our in-house Smart Contract software developed on the Ethereum platform. The Sharding approach improved the P2P blockchain performance in terms of computational complexity and processing time in real-time operations. Therefore, the probability of conflicts among aircraft in a swarm environment was significantly reduced using our new methodology and algorithm. Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management)
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