Aerospace

23 pages, 4872 KiB

Open AccessArticle

Minimisation of Failure Transients in a Fail-Safe Electro-Mechanical Actuator Employed for the Flap Movables of a High-Speed Helicopter-Plane

by Gianpietro Di Rito, Romain Kovel, Marco Nardeschi, Nicola Borgarelli and Benedetto Luciano

Aerospace 2022, 9(9), 527; https://doi.org/10.3390/aerospace9090527 - 19 Sep 2022

Viewed by 2863

Abstract

The work deals with the model-based characterization of the failure transients of a fail-safe rotary EMA developed by Umbragroup (Italy) for the flap movables of the RACER helicopter-plane by Airbus Helicopters (France). Since the reference application requires quasi-static position-tracking with high disturbance-rejection capability, [...] Read more.

The work deals with the model-based characterization of the failure transients of a fail-safe rotary EMA developed by Umbragroup (Italy) for the flap movables of the RACER helicopter-plane by Airbus Helicopters (France). Since the reference application requires quasi-static position-tracking with high disturbance-rejection capability, the attention is focused on control hardover faults which determine an actuator runaway from the commanded setpoint. To perform the study, a high-fidelity nonlinear model of the EMA is developed from physical first principles and the main features of health-monitoring and closed-loop control functions (integrating the conventional nested loops architecture with a deformation feedback loop enhancing the actuator stiffness) are presented. The EMA model is then validated with experiments by identifying its parameters by ad-hoc tests. Simulation results are finally proposed to characterize the failure transients in worst case scenarios by highlighting the importance of using a specifically designed back-electromotive damper circuitry into the EMA power electronics to limit the position deviation after the fault detection. Full article

(This article belongs to the Special Issue Electro-Mechanical Actuators for Safety-Critical Aerospace Applications)

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27 pages, 63552 KiB

Open AccessArticle

Improved Delayed Detached-Eddy Investigations on the Flow Control of the Leading-Edge Flat Spoiler of the Cavity in the Low-Aspect-Ratio Aircraft

by Pengcheng Cui, Guiyu Zhou, Yaobing Zhang, Hongyin Jia, Xiaojun Wu, Mingsheng Ma, Huan Li and Bing Chen

Aerospace 2022, 9(9), 526; https://doi.org/10.3390/aerospace9090526 - 19 Sep 2022

Cited by 4 | Viewed by 1936

Abstract

The internal weapon bay is widely used in modern aircraft; however, because the unsteady flows of the cavity would cause dangerous store separation and intense aerodynamic noise, the leading-edge spoiler is an easy and efficient passive flow-control method. The flow control of the [...] Read more.

The internal weapon bay is widely used in modern aircraft; however, because the unsteady flows of the cavity would cause dangerous store separation and intense aerodynamic noise, the leading-edge spoiler is an easy and efficient passive flow-control method. The flow control of the leading-edge flat spoiler before the cavity of a low-aspect-ratio flying-wing aircraft is investigated based on numerical simulation. Numerical results show that the leading-edge flat spoiler completely changes the cavity flow; it obviously lifts up the shear layer and reduces the pressure inside the cavity. For the store separation from the weapon bay, the leading-edge flat spoiler is a very good passive flow-control method that curbs the nose-up trend of the store and produces a safe and stable store separation. Besides, the leading-edge spoiler reduces the noise in the rear of the cavity (max 8.2 dB), but increases the noise in the middle of the cavity (max 11.3 dB). In addition, the leading-edge spoiler brings in a large drag increase to the aircraft (39.41% when the height of spoiler is 0.2 m), which would affect the operational stability of the aircraft. The results of this paper could provide a reference for the flow control of weapon bays and the design of aircraft. Full article

(This article belongs to the Section Aeronautics)

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18 pages, 5729 KiB

Open AccessArticle

Efficient Numerical Integration Algorithm of Probabilistic Risk Assessment for Aero-Engine Rotors Considering In-Service Inspection Uncertainties

by Guo Li, Junbo Liu, Huimin Zhou, Liangliang Zuo and Shuiting Ding

Aerospace 2022, 9(9), 525; https://doi.org/10.3390/aerospace9090525 - 18 Sep 2022

Cited by 4 | Viewed by 1537

Abstract

Numerical integration methods have the characteristics of high efficiency and precision, making them attractive for aero-engine probabilistic risk assessment and design optimization of an inspection plan. One factor that makes the numerical integration method a suitable approach to in-service inspection uncertainties is the [...] Read more.

Numerical integration methods have the characteristics of high efficiency and precision, making them attractive for aero-engine probabilistic risk assessment and design optimization of an inspection plan. One factor that makes the numerical integration method a suitable approach to in-service inspection uncertainties is the explicit derivation of the integration formula and integration domains. This explicit derivation ensures accurate characterization of a multivariable system’s failure risk evolution mechanism. This study develops an efficient numerical integration algorithm for probabilistic risk assessment considering in-service inspection uncertainties. The principle of probability conservation is applied to the transformation of the integration domain from the current flight cycle to the initial (N = 0) computational space. Consequently, the integration formula of failure probability is deduced, and a detailed mathematical demonstration of the proposed method is provided. An actual compressor disk is evaluated using the efficient numerical integration algorithm and the Monte Carlo simulation to validate the accuracy and efficiency of the proposed method. Results show that the time cost of the proposed algorithm is dozens of times lower than that of the Monte Carlo simulation, with a maximum relative error of 5%. Thus, the efficient numerical integration algorithm can be applied to failure analysis in the airworthiness design of commercial aero-engine components. Full article

(This article belongs to the Section Aeronautics)

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14 pages, 2630 KiB

Open AccessArticle

Spectrum of Corona Discharges and Electric Arcs in Air under Aeronautical Pressure Conditions

by Jordi-Roger Riba

Aerospace 2022, 9(9), 524; https://doi.org/10.3390/aerospace9090524 - 18 Sep 2022

Cited by 6 | Viewed by 2322

Abstract

Due to the increase in electrical power demand, future more electric and all-electric aircraft designs will operate at higher voltage levels compared to current aircraft. Due to higher voltage levels and reduced operating pressure, insulation systems will be at risk. Air is the [...] Read more.

Due to the increase in electrical power demand, future more electric and all-electric aircraft designs will operate at higher voltage levels compared to current aircraft. Due to higher voltage levels and reduced operating pressure, insulation systems will be at risk. Air is the main insulating medium, and it is well known that its dielectric strength decreases considerably with operating pressure. Although electrical discharges can be detected by different techniques, optical methods are very attractive due to their sensitivity and immunity to acoustic and electromagnetic noise typical of aeronautical environments. This work analyzes the UV-visible spectrum of corona discharges and electric arcs in the 10–100 kPa pressure range, which covers most of the aeronautical applications, due to the lack of experimental data for this pressure range. The data presented in this work are important to select the most suitable optical sensors to detect electrical discharges at an early stage, before significant damage occurs. This approach will help implement preventive maintenance plans and increase aircraft safety. The results presented in this paper can also be applied to other areas, such as monitoring of discharges in power lines, particularly those located in high-altitude regions. Full article

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16 pages, 4004 KiB

Open AccessArticle

Investigation on the Reynolds Number Effect of a Flying Wing Model with Large Sweep Angle and Small Aspect Ratio

by Peng Lin, Jifei Wu, Lianshan Lu, Neng Xiong, Dawei Liu, Jichuan Su, Guangyuan Liu, Yang Tao, Junqiang Wu and Xueqiang Liu

Aerospace 2022, 9(9), 523; https://doi.org/10.3390/aerospace9090523 - 18 Sep 2022

Cited by 4 | Viewed by 2374

Abstract

The effect of the Reynolds number on the flying wing common research model with a large sweep angle and small aspect ratio is studied by numerical simulation. The helicity cross-flow transition correction of the Langtry–Menter model is established in view of the deficient [...] Read more.

The effect of the Reynolds number on the flying wing common research model with a large sweep angle and small aspect ratio is studied by numerical simulation. The helicity cross-flow transition correction of the Langtry–Menter model is established in view of the deficient prediction accuracies of existing transition prediction models in simulating cross-flow transition, and the helicity parameters are calibrated to improve the prediction accuracy of the numerical method. The transition prediction method is verified by the test results of the standard model transition of the DLR-F5 wing and small-aspect-ratio flying wing. At the same time, the numerical method is effectively verified by comparing it to the aerodynamic/torque results of the standard model of the small-aspect-ratio flying wing. On this basis, the variation laws with the Reynolds number are analyzed for the aerodynamic and flow field characteristics of the flying wing common research model with a large sweep angle and small aspect ratio. The numerical simulation is mainly carried out in the high subsonic speed range (M = 0.9), and the simulated Reynolds number range is from 2 × 10⁶ to 80 × 10⁶, which includes the test Reynolds number and flight Reynolds number. The influence of turbulence on the surface flow pattern and drag characteristics of the small-aspect-ratio standard model is analyzed. Calculation results show that when the turbulence is greater than 0.4%, it has a considerable influence on the surface laminar flow range and total drag coefficient. The results reveal that the Reynolds number mainly affects the magnitude of friction in the cruise state (small angle of attack). The problem of the Reynolds number in the self-aligning region of the flying wing standard model with a small aspect ratio is further studied, and the Reynolds number is found to be greater than 10 × 10⁶. The drag and lift coefficients after the approach are close to the Reynolds number in the self-aligning region of the flying wing standard model with a small aspect ratio. Full article

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17 pages, 1782 KiB

Open AccessArticle

Assessment of Potential Conflict Detection by the ATCo

by Raquel Delgado-Aguilera Jurado, Víctor Fernando Gómez Comendador, María Zamarreño Suárez, Francisco Pérez Moreno, Christian Eduardo Verdonk Gallego and Rosa María Arnaldo Valdés

Aerospace 2022, 9(9), 522; https://doi.org/10.3390/aerospace9090522 - 17 Sep 2022

Cited by 2 | Viewed by 1737

Abstract

The main goal of this article is to analyse the probability of detecting potential conflicts by the Air Traffic Controller (ATCo). The ATCo ensures the safety of aircraft and one of its main functions is collision avoidance. Collision avoidance is known as separation [...] Read more.

The main goal of this article is to analyse the probability of detecting potential conflicts by the Air Traffic Controller (ATCo). The ATCo ensures the safety of aircraft and one of its main functions is collision avoidance. Collision avoidance is known as separation provision and this term means assuring the safe distance between each aircraft by sides, vertical and longitudinal minimums of separation. The air traffic controller must ensure a high level of airspace capacity. The work performance is related to high demands on individual characteristics, knowledge, skills and, of course, air traffic characteristics. In addition to analysing the probability of detecting potential conflicts, the study of the most influential factors on this safety event is considered of special relevance since the ATCo represents the last executive section of the air traffic control system and failure to detect potential conflicts could lead to a possible infringement of the minimum separation distances between aircraft or even a collision. In order to carry out this approach, Bayesian Networks will be used due to their high predictive capacity. In addition, a dual approach based on knowledge and real operational data provided by an ANSP will be used. These data are one of the great advantages of this study compared to those included in the current literature. Full article

(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management)

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22 pages, 3255 KiB

Open AccessArticle

A Practical Interlacing-Based Coverage Path Planning Method for Fixed-Wing UAV Photogrammetry in Convex Polygon Regions

by Junhua Huang, Wenxing Fu, Sheng Luo, Chenxin Wang, Bo Zhang and Yu Bai

Aerospace 2022, 9(9), 521; https://doi.org/10.3390/aerospace9090521 - 17 Sep 2022

Cited by 3 | Viewed by 1731

Abstract

This paper investigates the coverage path planning problem for a fixed-wing UAV in convex polygon regions with several practical task requirements in photogrammetry considered. A typical camera model pointing forward-down for photogrammetric application is developed. In addition, the coordinates of the region vertices [...] Read more.

This paper investigates the coverage path planning problem for a fixed-wing UAV in convex polygon regions with several practical task requirements in photogrammetry considered. A typical camera model pointing forward-down for photogrammetric application is developed. In addition, the coordinates of the region vertices are converted from the WGS-84 coordinate system to the local ENU coordinate system for path planning convenience. The relationship between the minimum turning radius and the camera footprint is fully studied and the span coefficient of the fixed-wing UAV is first proposed. A novel flight pattern, named as the interlaced back-and-forth pattern in this paper, is presented accordingly. The proposed algorithm is compared with a traditional back-and-forth pattern in mathematics and several important results are given. Then, a practical low-computation algorithm for waypoints generation is developed. Finally, simulation results validate the effectiveness of the proposed method. Full article

(This article belongs to the Section Aeronautics)

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11 pages, 11645 KiB

Open AccessArticle

A Novel Deep Learning-Based Relabeling Architecture for Space Objects Detection from Partially Annotated Astronomical Images

by Florin Dumitrescu, Bogdan Ceachi, Ciprian-Octavian Truică, Mihai Trăscău and Adina Magda Florea

Aerospace 2022, 9(9), 520; https://doi.org/10.3390/aerospace9090520 - 17 Sep 2022

Cited by 3 | Viewed by 1465

Abstract

Space Surveillance and Tracking is a task that requires the development of systems that can accurately discriminate between natural and man-made objects that orbit around Earth. To manage the discrimination between these objects, it is required to analyze a large amount of partially [...] Read more.

Space Surveillance and Tracking is a task that requires the development of systems that can accurately discriminate between natural and man-made objects that orbit around Earth. To manage the discrimination between these objects, it is required to analyze a large amount of partially annotated astronomical images collected using a network of on-ground and potentially space-based optical telescopes. Thus, the main objective of this article is to propose a novel architecture that improves the automatic annotation of astronomical images. To achieve this objective, we present a new method for automatic detection and classification of space objects (point-like and streaks) in a supervised manner, given real-world partially annotated images in the FITS (Flexible Image Transport System) format. Results are strongly dependent on the preprocessing techniques applied to the images. Therefore, different techniques were tested including our method for object filtering and bounding box extraction. Based on our relabeling pipeline, we can easily follow how the number of detected objects is gradually increasing after each iteration, achieving a mean average precision of 98%. Full article

(This article belongs to the Section Astronautics & Space Science)

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20 pages, 5890 KiB

Open AccessArticle

Configuration Stability Analysis for Geocentric Space Gravitational-Wave Observatories

by Xingyu Zhou, Feida Jia and Xiangyu Li

Aerospace 2022, 9(9), 519; https://doi.org/10.3390/aerospace9090519 - 17 Sep 2022

Cited by 5 | Viewed by 1366

Abstract

Long-term configuration stability is essential for a space-based gravitational-wave observatory, which can be affected by orbit insertion errors. This paper investigated the stability of a geocentric gravitational-wave observatory from the view of the configuration uncertainty propagation. The effects of the orbit insertion errors [...] Read more.

Long-term configuration stability is essential for a space-based gravitational-wave observatory, which can be affected by orbit insertion errors. This paper investigated the stability of a geocentric gravitational-wave observatory from the view of the configuration uncertainty propagation. The effects of the orbit insertion errors on the configuration stability are propagated using the Unscented Transformation (UT). The best UT tuning factor is selected based on the accuracy analysis of different UT tuning factors. The effects of the position and velocity insertion errors in different directions are firstly discussed. Compared with the Monte Carlo simulations, the UT method has relative errors of no more than 2.7%, while the time cost is only 3.6%. It is found that the radial position and tangential velocity insertion errors have the largest influence on the configuration stability. Finally, based on the proposed method, the stability domain of the geocentric space gravitational-wave detection constellation is investigated by considering two kinds of insertion errors, i.e., independent and identically distributed insertion errors and insertion errors in spatial directions. The analysis results in this paper can be potentially useful for the configuration design of a geocentric gravitational-wave observatory. Full article

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25 pages, 1594 KiB

Open AccessArticle

Active Fault-Tolerant Control for Quadrotor UAV against Sensor Fault Diagnosed by the Auto Sequential Random Forest

by Shaojie Ai, Jia Song, Guobiao Cai and Kai Zhao

Aerospace 2022, 9(9), 518; https://doi.org/10.3390/aerospace9090518 - 17 Sep 2022

Cited by 7 | Viewed by 1886

Abstract

Active disturbance rejection control (ADRC) is a model-independent method widely used in passive fault-tolerant control of the quadrotor unmanned aerial vehicle. While ADRC’s effectiveness in actuator fault treatment has been proven, its tolerance to sensor faults requires improvements. In this paper, an ADRC-based [...] Read more.

Active disturbance rejection control (ADRC) is a model-independent method widely used in passive fault-tolerant control of the quadrotor unmanned aerial vehicle. While ADRC’s effectiveness in actuator fault treatment has been proven, its tolerance to sensor faults requires improvements. In this paper, an ADRC-based active fault-tolerant control (AFTC) scheme is proposed to control the flying attitude against sensor fault for reliability enhancement. Specifically, a semi-model-dependent state tracker is raised to reduce the influence of slow tracking, and accentuate the sensor fault even in varying maneuvers. Derived from the random forest, an enhanced method named auto sequential random forest is designed and applied to isolate and identify faults in real time. Once the tolerance compensation is generated with the fault information, a high-performance AFTC is achieved. The simulation results show that the proposed method can effectively follow the residual when a sensor fault and a change of maneuver occur concurrently. Precise fault information is obtained within 0.04 s, even for small faults on the noise level. The diagnosis accuracy is greater than 86.05% (100% when small faults are excluded), and the identification precision exceeds 97.25%. The short settling time (0.176 s when the small fault is excluded) and modest steady-state error validate the advanced and robust tolerance performance of the proposed AFTC method. Full article

(This article belongs to the Special Issue Latest Advancements in Aeronautics and Astronautics: Celebrating the 70th Anniversary of Beihang University)

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19 pages, 6293 KiB

Open AccessArticle

Decompression Load Analysis in Large Passenger Planes with Windshield Cracked

by Wenbin He, Xi Yang, Ding Luo, Jiang Lei, Zhimao Li, Shiquan Lin and Congxiao Zhang

Aerospace 2022, 9(9), 517; https://doi.org/10.3390/aerospace9090517 - 16 Sep 2022

Viewed by 2488

Abstract

To prevent the possible accident of a large passenger plane due to rapid decompression, transient load analysis is of vital importance in the assessment of structure strength and also an important clause of airworthiness standard. A 0-D isentropic model and a 1-D model [...] Read more.

To prevent the possible accident of a large passenger plane due to rapid decompression, transient load analysis is of vital importance in the assessment of structure strength and also an important clause of airworthiness standard. A 0-D isentropic model and a 1-D model based on the characteristic line are developed to simulate the rapid decompression process of the cockpit-cabin model due to a cracked windshield. The accuracy of these models is presented by comparing them with experiments and 3-D CFD simulations. Then, the 1-D model is applied to study the influence of cabin and cockpit volume, windshield and decompression panel area, compartments, and environment pressure on the decompression load. The non-dimensional decompression time and the non-dimensional decompression load are developed to evaluate the decompression characteristics, and the correlation equations are established. The relative deviation between the results of the correlation equation fit and the results of the one-dimensional simulation is less than 3%. This work provides a new engineering method for structure strength design and decompression load analysis with high accuracy and low resource consumption. Full article

(This article belongs to the Special Issue Aircraft Design (SI-4/2022))

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19 pages, 4264 KiB

Open AccessArticle

Clustering Federated Learning for Bearing Fault Diagnosis in Aerospace Applications with a Self-Attention Mechanism

by Weihua Li, Wansheng Yang, Gang Jin, Junbin Chen, Jipu Li, Ruyi Huang and Zhuyun Chen

Aerospace 2022, 9(9), 516; https://doi.org/10.3390/aerospace9090516 - 15 Sep 2022

Cited by 8 | Viewed by 2423

Abstract

Bearings, as the key mechanical components of rotary machinery, are widely used in modern aerospace equipment, such as helicopters and aero-engines. Intelligent fault diagnosis, as the main function of prognostic health management systems, plays a critical role in maintaining equipment safety in aerospace [...] Read more.

Bearings, as the key mechanical components of rotary machinery, are widely used in modern aerospace equipment, such as helicopters and aero-engines. Intelligent fault diagnosis, as the main function of prognostic health management systems, plays a critical role in maintaining equipment safety in aerospace applications. Recently, data-driven intelligent diagnosis approaches have achieved great success due to the availability of large-scale, high-quality, and complete labeled data. However, in a real application, labeled data is often scarce because it requires manual labeling, which is time-consuming and labor-intensive. Meanwhile, health monitoring data are usually scattered in different regions or equipment in the form of data islands. Traditional fault diagnosis techniques fail to gather enough data for model training due to data security, economic conflict, relative laws, and other reasons. Therefore, it is a challenge to effectively combine the data advantages of different equipment to develop an intelligent diagnosis model with better performance. To address this issue, a novel clustering federated learning (CFL) method with a self-attention mechanism is proposed for bearing fault diagnosis. Firstly, a deep neural network with a self-attention mechanism is developed in a convolutional pipe for feature extraction, which can capture local and global information from raw input. Then, the CFL is further constructed to gather the data from different equipment with similar data distribution in an unsupervised manner. Finally, the CFL-based diagnosis model can be well trained by fully utilizing the distributed data, while ensuring data privacy safety. Experiments are carried out with three different bearing datasets in aerospace applications. The effectiveness and the superiority of the proposed method have been validated compared with other popular fault diagnosis schemes. Full article

(This article belongs to the Special Issue Application of Data Science to Aviation II)

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30 pages, 10706 KiB

Open AccessArticle

Numerical Aeroelastic Analysis of a High-Aspect-Ratio Wing Considering Skin Flexibility

by Zhao Yang and Jie Li

Aerospace 2022, 9(9), 515; https://doi.org/10.3390/aerospace9090515 - 15 Sep 2022

Cited by 1 | Viewed by 1611

Abstract

Aeroelastic deformation of the high-aspect-ratio wing from a solar-powered UAV will definitely lead to the difference of its performance between design and actual flight. In the present study, the numerical fluid–structural coupling analysis of a wing with skin flexibility is performed by a [...] Read more.

Aeroelastic deformation of the high-aspect-ratio wing from a solar-powered UAV will definitely lead to the difference of its performance between design and actual flight. In the present study, the numerical fluid–structural coupling analysis of a wing with skin flexibility is performed by a loosely coupled partitioned approach. The bidirectional coupling framework is established by combining an in-house developed computational fluid dynamics (CFD) code with a computational structural dynamics (CSD) analysis solver and a time-adaptive coupling strategy is integrated in it to improve the computational stability and efficiency of the process. With the proposed method, the fluid–structure interactions between the wing and fluid are simulated, and the results are compared between the deformed wing and its rigid counterpart regarding the aerodynamic coefficients, transition location, and flow structures at large angles of attack. It can be observed that after deformation, the laminar transition on the upper surface is triggered earlier at small angles of attack and the stall characteristic becomes worse. The calculated difference in aerodynamic performance between the deformed and the designed rigid wing can help designers better understand the wing’s real performance in the preliminary stage of design. Full article

(This article belongs to the Section Aeronautics)

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13 pages, 1817 KiB

Open AccessArticle

Design of a Maglev Stewart Platform for the Microgravity Vibration Isolation

by He Ma, Weichao Chi, Caihua Wang and Jia Luo

Aerospace 2022, 9(9), 514; https://doi.org/10.3390/aerospace9090514 - 15 Sep 2022

Cited by 5 | Viewed by 1635

Abstract

Vibration isolation mechanisms are usually installed on spacecraft between the vibration sources and the payload to ensure that precision instruments work properly. This paper proposes a novel maglev Stewart platform for vibration isolation in a microgravity environment. The maglev Stewart platform combines the [...] Read more.

Vibration isolation mechanisms are usually installed on spacecraft between the vibration sources and the payload to ensure that precision instruments work properly. This paper proposes a novel maglev Stewart platform for vibration isolation in a microgravity environment. The maglev Stewart platform combines the quasi-zero stiffness of maglev actuators and the high maneuverability of the Stewart platform. The dynamic of the legs and the payload platform is analyzed, and the linear active disturbance rejection control (LADRC) algorithm is used to decouple the legs and cancel the total disturbance in the linear feedback. The simulation studies show that with the maglev Stewart platform, there is no longer any obvious resonance. The transmission ratio of vibration can be reduced significantly compared with the traditional elastic Stewart platform. Last but not least, the influence of two control parameters on vibration isolation performance is connected to certain physical meaning of the vibration problem. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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21 pages, 4177 KiB

Open AccessArticle

Identification and Quantification of Contributing Factors to the Criticality of Aircraft Loss of Separation

by Lidia Serrano-Mira, Marta Pérez Maroto, Eduardo S. Ayra, Javier Alberto Pérez-Castán, Schon Z. Y. Liang-Cheng, Víctor Gordo Arias and Luis Pérez-Sanz

Aerospace 2022, 9(9), 513; https://doi.org/10.3390/aerospace9090513 - 15 Sep 2022

Cited by 3 | Viewed by 2034

Abstract

A Mid-Air Collision (MAC) is a fatal event with tragic consequences. To reduce the risk of a MAC, it is imperative to understand the precursors that trigger it. A primary precursor to a MAC is a loss of separation (LOS) or a separation [...] Read more.

A Mid-Air Collision (MAC) is a fatal event with tragic consequences. To reduce the risk of a MAC, it is imperative to understand the precursors that trigger it. A primary precursor to a MAC is a loss of separation (LOS) or a separation infringement. This study develops a model to identify the factors contributing to a LOS between aircraft pairs. A Bayesian Network (BN) model is used to estimate the conditional dependencies of the factors affecting criticality, that is, how close the LOS has come to becoming a collision. This probabilistic model is built using GeNIe software from data (based on a database created from incident analysis) and expert judgment. The results of the model allow identification of how factors related to the scenario, the human factor (ATC and flight crew) or the technical systems, affect the criticality of the LOS. Based on this information, it is possible to exclude irrelevant elements that do not contribute or whose influence could be neglected, and to prioritize work on the most important ones, in order to increase ATM safety. Full article

(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management)

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15 pages, 4584 KiB

Open AccessArticle

Predicting Geometrical Variation in Fabricated Assemblies Using a Digital Twin Approach Including a Novel Non-Nominal Welding Simulation

by Hugo Hultman, Stefan Cedergren, Kristina Wärmefjord and Rikard Söderberg

Aerospace 2022, 9(9), 512; https://doi.org/10.3390/aerospace9090512 - 14 Sep 2022

Cited by 5 | Viewed by 1533

Abstract

The aerospace industry faces constantly increasing demands on performance and reliability, especially within the vital area of engine development. New technologies are needed in order to push the limits of high precision manufacturing processes for the next generation of aircraft engines. An increased [...] Read more.

The aerospace industry faces constantly increasing demands on performance and reliability, especially within the vital area of engine development. New technologies are needed in order to push the limits of high precision manufacturing processes for the next generation of aircraft engines. An increased use of in-line data collection in manufacturing is creating an opportunity to individualize each assembly operation rather than treating them identically. Welding is common in this context, and the interaction between welding distortion and variation in part geometries is difficult to predict and manage in products with tight tolerances. This paper proposes an approach based on the Digital Twin paradigm, aiming to increase geometrical quality by combining the novel SCV (Steady-state Convex hull Volumetric shrinkage) method for non-nominal welding simulation with geometrical data collected from 3D scanning of parts. A case study is presented where two parts are scanned and then welded together into an assembly. The scan data is used as input for a non-nominal welding simulation, and the result of the simulation is compared directly to scan data from the real welded assembly. Three different welding simulation methods are used and assessed based on simulation speed and ability to predict the real welding result. The segmented SCV method for welding simulation shows promising potential for this implementation, delivering good prediction accuracy and high simulation speed. Full article

(This article belongs to the Section Aeronautics)

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23 pages, 14171 KiB

Open AccessArticle

Theoretical and Experimental Investigation of Geomagnetic Energy Effect for LEO Debris Deorbiting

by Guanhua Feng, Chen Zhang, Heng Zhang and Wenhao Li

Aerospace 2022, 9(9), 511; https://doi.org/10.3390/aerospace9090511 - 14 Sep 2022

Cited by 2 | Viewed by 1430

Abstract

Space debris is increasingly problematic and needs active removal, especially in low Earth orbits (LEO). Paying for the vast cost of the disposal of debris from the situation is still inevitable even though pivotal technical hurdles have been overcome with the growing maturity [...] Read more.

Space debris is increasingly problematic and needs active removal, especially in low Earth orbits (LEO). Paying for the vast cost of the disposal of debris from the situation is still inevitable even though pivotal technical hurdles have been overcome with the growing maturity of capturing and deorbiting methods. To this end, a novel geomagnetic energy (GME) propellant approach is firstly proposed to propel a spinning tethered spacecraft for LEO debris deorbiting, without the use of expendable fuel and a large-length tether. In this method, the time-cumulative effect of the interacted torque of the spacecraft’s electromagnet and geomagnetic field is used to accelerate the rotating system for GME storage, and the space momentum exchange from the angular momentum of system to the linear momentum of debris is introduced to deorbit the debris for GME release. Next, an on-orbit directional GME storage mechanism is built, and the corresponding two optimal strategies are put forward. Both theoretical and simulation results demonstrate that GME can be stored in the expected direction on any inclined LEO below 1000 km. Deorbiting kg-level debris can be accomplished within several orbital periods with the existing magnetorquer technology. Finally, proof-of-principle experiments of the GME effect are performed and elementarily validate the LEO GME utilization in space. Full article

(This article belongs to the Special Issue Space Debris Removal: Challenges and Opportunities)

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19 pages, 3026 KiB

Open AccessArticle

Two-Level Hierarchical-Interaction-Based Group Formation Control for MAV/UAVs

by Huan Wang, Shuguang Liu, Maolong Lv and Boyang Zhang

Aerospace 2022, 9(9), 510; https://doi.org/10.3390/aerospace9090510 - 14 Sep 2022

Cited by 4 | Viewed by 1356

Abstract

Cooperative group formation control of manned/unmanned aircraft vehicles (MAV/UAVs) using a hierarchical framework can be more efficient and flexible than centralized control strategies. In this paper, a two-level hierarchical-interaction-based cooperative control strategy is proposed for the MAV/UAVs group formation. At the upper level, [...] Read more.

Cooperative group formation control of manned/unmanned aircraft vehicles (MAV/UAVs) using a hierarchical framework can be more efficient and flexible than centralized control strategies. In this paper, a two-level hierarchical-interaction-based cooperative control strategy is proposed for the MAV/UAVs group formation. At the upper level, combined with the nonlinear disturbance observer (NDO) and dynamic surface control (DSC) algorithm, a trajectory tracking problem with external disturbances for MAV is formulated. At the lower level, the leader-following formation controller is utilized to deal with the sub-formation keeping control problem for UAVs, based on the sliding mode disturbance observer and fast terminal sliding mode control law, and the robust performance and control accuracy are effectively improved. Moreover, the overall stability of the MAV/UAVs system is demonstrated using Lyapunov theory. The proposed approach is evaluated by simulation under the ground penetration combat mission for MAV/UAVs, and the performance is compared with that of other control strategies. Full article

(This article belongs to the Special Issue Learning-Based Intelligent Control in Aerospace Applications)

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18 pages, 4817 KiB

Open AccessArticle

Shape Sensing for an UAV Composite Half-Wing: Numerical Comparison between Modal Method and Ko’s Displacement Theory

by Filippo Valoriani, Marco Esposito and Marco Gherlone

Aerospace 2022, 9(9), 509; https://doi.org/10.3390/aerospace9090509 - 13 Sep 2022

Cited by 3 | Viewed by 1465

Abstract

Shape sensing is the reconstruction of the displacement field of a structure from some discrete surface strain measurements and is a key technology for structural health monitoring. The aim of this paper is to compare two approaches to shape sensing that have been [...] Read more.

Shape sensing is the reconstruction of the displacement field of a structure from some discrete surface strain measurements and is a key technology for structural health monitoring. The aim of this paper is to compare two approaches to shape sensing that have been shown to be more efficient, especially for aircraft structures applications, in terms of required input strain measurements: the Ko’s Displacement Theory and the Modal Method. An object of the shape-sensing analysis is the half-wing of a multirotor UAV. The approaches are summarized in order to set the framework for the numerical comparative investigation. Then, the multirotor UAV is presented and a finite element model of its half-wing is used to simulate the static response to straight-and-level flight conditions. For a given common set of surface strain measurement points, Ko’s Displacement Theory and the Modal Method are compared in terms of accuracy of the reconstructed half-wing deflection and twist angle. The Modal Method is shown to be more accurate than Ko’s Displacement Theory, especially for the evaluation of the deflection field. Further numerical analyses show that the Modal Method is influenced by the set of mode shapes included in the analysis and that excellent reconstructed deflections can be obtained with a reduced number of sensors, thus assessing the approach as an efficient shape-sensing tool for aircraft structures real applications. Full article

(This article belongs to the Section Aeronautics)

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19 pages, 6116 KiB

Open AccessArticle

Aerodynamic Optimization of Transonic Rotor Using Radial Basis Function Based Deformation and Data-Driven Differential Evolution Optimizer

by Yi Liu, Jiang Chen, Jinxin Cheng and Hang Xiang

Aerospace 2022, 9(9), 508; https://doi.org/10.3390/aerospace9090508 - 13 Sep 2022

Cited by 4 | Viewed by 1413

Abstract

The complicated flow conditions and massive design parameters bring two main difficulties to the aerodynamic optimization of axial compressors: expensive evaluations and numerous optimization variables. To address these challenges, this paper establishes a novel fast aerodynamic optimization platform for axial compressors, consisting of [...] Read more.

The complicated flow conditions and massive design parameters bring two main difficulties to the aerodynamic optimization of axial compressors: expensive evaluations and numerous optimization variables. To address these challenges, this paper establishes a novel fast aerodynamic optimization platform for axial compressors, consisting of a radial basic function (RBF)-based blade parameterization method, a data-driven differential evolution optimizer, and a computational fluid dynamic (CFD) solver. As a versatile interpolation method, RBF is used as the shape parameterization and deformation technique to reduce optimization variables. Aiming to acquire competitive solutions in limited steps, a data-driven evolution optimizer is developed, named the pre-screen surrogate model assistant differential evolution (pre-SADE) optimizer. Different from most surrogate model-assisted evolutionary algorithms, surrogate models in pre-SADE are used to screen the samples, rather than directly estimate them, in each generation to reduce expensive evaluations. The polynomial regression model, Kriging model, and RBF model are integrated in the surrogate model to improve the accuracy. To further save optimization time, the optimizer also integrates parallel task management programs. The aerodynamic optimization of a transonic rotor (NASA Rotor 37) is performed as the validation of the platform. A differential evolution (DE) optimizer and another surrogate model-assisted algorithm, committee-based active learning for surrogate model assisted particle swarm optimization (CAL-SAPSO), are introduced for the comparison runs. After optimization, the adiabatic efficiency, total pressure ratio, and surge margin are, respectively, increased by 1.47%, 1.0%, and 0.79% compared to the initial rotor. In the same limited steps, pre-SADE gets a 0.57% and 0.51% higher rotor adiabatic efficiency than DE and CAL-SAPSO, respectively. With the help of parallel techniques, pre-SADE and DE save half the optimization time compared to CAL-SAPSO. The results verify the effectiveness and the rapidity of the fast aerodynamic optimization platform. Full article

(This article belongs to the Special Issue Aerodynamic Shape Optimization for Aerospace Engineering Applications)

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12 pages, 4158 KiB

Open AccessArticle

Digitalization and Quantitative Flow Visualization of Surrounding Flow over a Specially-Shaped Column-Frame by Luminescent Mini-Tufts Method

by Shuang Ma and Lin Chen

Aerospace 2022, 9(9), 507; https://doi.org/10.3390/aerospace9090507 - 11 Sep 2022

Viewed by 1578

Abstract

The luminescent mini-tufts method is widely used for flow visualization for quantitative field analysis. A set of numerical methods for digitalization of 3D surfaces surrounding flows with luminescent mini-tufts has been developed in this study. The procedure includes digital image pre-processing, mini-tufts recognition, [...] Read more.

The luminescent mini-tufts method is widely used for flow visualization for quantitative field analysis. A set of numerical methods for digitalization of 3D surfaces surrounding flows with luminescent mini-tufts has been developed in this study. The procedure includes digital image pre-processing, mini-tufts recognition, mean field mini-tufts calculation, inclination angle calculation, oscillation area calculation, etc. The model is subjected to a newly proposed digitalization method and realized by in-house code. The time mean angle’s changing mode, along the mini-tuft, are analyzed, which shows that the mini-tuft follows the inflow well. The transient oscillation of mini-tufts is observed as well, which shows that on the middle part of the irregularity cylinder, the flow oscillates more intensively. Full article

(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)

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20 pages, 13255 KiB

Open AccessArticle

Numerical Study of the Induced Shock on the Mixing Augmentation of Hydrogen Counter-Flow Jet in the Supersonic Flow

by Yi Han, Chibing Shen, Zhaobo Du and Haoran Tang

Aerospace 2022, 9(9), 506; https://doi.org/10.3390/aerospace9090506 - 11 Sep 2022

Cited by 3 | Viewed by 1815

Abstract

In the scramjet engine, the injection and mixing of fuel are the basis for organizing efficient combustion. The shock wave/jet shear layer interaction is one of the methods used to enhance fuel mixing in supersonic flow. In this research, the effect of the [...] Read more.

In the scramjet engine, the injection and mixing of fuel are the basis for organizing efficient combustion. The shock wave/jet shear layer interaction is one of the methods used to enhance fuel mixing in supersonic flow. In this research, the effect of the induced shock wave on the mixing augmentation of fuel counter-flow jet is studied in the supersonic crossflow. The results show that the symmetrical setting of the shock wave generators (SWGs) has the highest mixing efficiency but brings a greater total pressure loss. In the specific range, the mixing efficiency increases with the increase in the angle of the SWG, while the total pressure recovery coefficient is the opposite. The induced oblique shock wave acting on the front of the fuel jet has an obvious influence on the flow field, resulting in the highest mixing efficiency. In the end, the analytic hierarchy process (AHP) is used to evaluate the extent of mixing augmentation by mixing parameters, which provides a decision-making idea for the scheme decision of mixing augmentation. Full article

(This article belongs to the Special Issue Jet Flow Analysis)

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30 pages, 6319 KiB

Open AccessArticle

Convex Optimization for Rendezvous and Proximity Operation via Birkhoff Pseudospectral Method

by Zhiwei Zhang, Dangjun Zhao, Xianbin Li, Chunyang Kong and Ming Su

Aerospace 2022, 9(9), 505; https://doi.org/10.3390/aerospace9090505 - 09 Sep 2022

Cited by 6 | Viewed by 1880

Abstract

Rapid and accurate rendezvous and proximity operations for spacecraft are crucial to the success of most space missions. In this paper, a sequential convex programming method, combined with the first-order and second-order Birkhoff pseudospectral methods, is proposed for the autonomous rendezvous and proximity [...] Read more.

Rapid and accurate rendezvous and proximity operations for spacecraft are crucial to the success of most space missions. In this paper, a sequential convex programming method, combined with the first-order and second-order Birkhoff pseudospectral methods, is proposed for the autonomous rendezvous and proximity operations of spacecraft. The original nonlinear and nonconvex close-range rendezvous problem with thrust constraints and no-fly zone constraints is converted into its convex version by using the sequential convexification techniques; then, the Birkhoff pseudospectral method is used to transcribe the dynamic constraints into a series of linear algebraic equality constraints, in other words, a convex second-order conic programming problem with a relatively small condition number. Thus, the resulting problem can be accurately and efficiently solved by a convex solver. The simulation results indicate that the proposed methods, especially the second-order Birkhoff pseudospectral method, have obvious advantages over other methods in computational efficiency and sensitivity. Full article

(This article belongs to the Special Issue Convex Optimization for Aerospace Guidance and Control Applications)

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42 pages, 11273 KiB

Open AccessArticle

Performance Evaluation for Launcher Testing Vehicle

by Teodor-Viorel Chelaru, Valentin Pană and Costin Ene

Aerospace 2022, 9(9), 504; https://doi.org/10.3390/aerospace9090504 - 09 Sep 2022

Viewed by 1200

Abstract

The paper’s purpose is to present a calculus model for a testing vehicle that can be used to validate guidance, navigation and control systems for reusable launchers in all flight phases. The technical solution is based on a throttleable engine with thrust vectoring [...] Read more.

The paper’s purpose is to present a calculus model for a testing vehicle that can be used to validate guidance, navigation and control systems for reusable launchers in all flight phases. The technical solution is based on a throttleable engine with thrust vectoring control and a reaction control system (RCS) used for roll. For calculus, we will develop a nonlinear model with six degrees of freedom, based on quaternion, extended with nonlinear equations that use pulse modulation in order to control roll. In order to synthesize the controller, we also develop a linear model similar to the launcher model. The paper analyzes two basic scenarios, first with the ascending and the descending flight phases and the second having a horizontal flight interleaved between ascending and descending flight phases, both scenarios being specific for reusable launchers. Based on these scenarios, the paper evaluates some performances of the proposed vehicle, namely flight envelope and guidance accuracy. Full article

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20 pages, 5223 KiB

Open AccessArticle

Implicit Extended Kalman Filter for Optical Terrain Relative Navigation Using Delayed Measurements

by Stefano Silvestrini, Margherita Piccinin, Giovanni Zanotti, Andrea Brandonisio, Paolo Lunghi and Michèle Lavagna

Aerospace 2022, 9(9), 503; https://doi.org/10.3390/aerospace9090503 - 09 Sep 2022

Cited by 9 | Viewed by 2446

Abstract

The exploration of celestial bodies such as the Moon, Mars, or even smaller ones such as comets and asteroids, is the next frontier of space exploration. One of the most interesting and attractive purposes from the scientific point of view in this field, [...] Read more.

The exploration of celestial bodies such as the Moon, Mars, or even smaller ones such as comets and asteroids, is the next frontier of space exploration. One of the most interesting and attractive purposes from the scientific point of view in this field, is the capability for a spacecraft to land on such bodies. Monocular cameras are widely adopted to perform this task due to their low cost and system complexity. Nevertheless, image-based algorithms for motion estimation range across different scales of complexities and computational loads. In this paper, a method to perform relative (or local) terrain navigation using frame-to-frame features correspondences and altimeter measurements is presented. The proposed image-based approach relies on the implementation of the implicit extended Kalman filter, which works using nonlinear dynamic models and corrections from measurements that are implicit functions of the state variables. In particular, here, the epipolar constraint, which is a geometric relationship between the feature point position vectors and the camera translation vector, is employed as the implicit measurement fused with altimeter updates. In realistic applications, the image processing routines require a certain amount of time to be executed. For this reason, the presented navigation system entails a fast cycle using altimeter measurements and a slow cycle with image-based updates. Moreover, the intrinsic delay of the feature matching execution is taken into account using a modified extrapolation method. Full article

(This article belongs to the Special Issue Recent Advances in Spacecraft Dynamics and Control)

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17 pages, 3082 KiB

Open AccessArticle

Research on Joint Ground Movement Optimization Based on Bilevel Programming

by Ruofei Sun, Jie Li, Kexin Niu, Yong Tian and Can Xu

Aerospace 2022, 9(9), 502; https://doi.org/10.3390/aerospace9090502 - 09 Sep 2022

Cited by 3 | Viewed by 1403

Abstract

Requirements of digitization, intellectualization, and integration for the programming and management of air transportation have been recommended as information technology booms. A variety of single ground movement optimization problems have been discussed with few taking the impact of other segments into account. In [...] Read more.

Requirements of digitization, intellectualization, and integration for the programming and management of air transportation have been recommended as information technology booms. A variety of single ground movement optimization problems have been discussed with few taking the impact of other segments into account. In this research, bilevel programming is applied to simultaneously consider three problems including the gate assignment, taxi path scheduling, and pushback time delay. For evaluating the strategy of gate assignment and measuring its connection with taxiing comprehensively, an auxiliary variable and the matching degree of gate and aircraft are introduced. In addition, an algorithm incorporating the genetic algorithm and routing algorithm is designed to obtain a solution with satisfactory performance in both taxi time and conflict risk. The scheme obtained also assigns aircraft to gates more appropriately and maintains the characteristics of environmental protection as well as high efficiency, showing considerable reliability in practice. Full article

(This article belongs to the Section Air Traffic and Transportation)

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19 pages, 12024 KiB

Open AccessArticle

Numerical Investigation on Detonation Initiation and Propagation with a Symmetric-Jet in Supersonic Combustible Gas

by Jian Dai and Linyuan Peng

Aerospace 2022, 9(9), 501; https://doi.org/10.3390/aerospace9090501 - 08 Sep 2022

Cited by 1 | Viewed by 1432

Abstract

In this study, supersonic gaseous detonation initiation and propagation by single- and symmetric-jets are compared, and the effects of symmetric-jets of different intensities on the detonation are further investigated to obtain a more comprehensive understanding of the initiation mechanism of hot jet in [...] Read more.

In this study, supersonic gaseous detonation initiation and propagation by single- and symmetric-jets are compared, and the effects of symmetric-jets of different intensities on the detonation are further investigated to obtain a more comprehensive understanding of the initiation mechanism of hot jet in supersonic mixtures. The two-dimensional reactive Navier–Stokes equations, together with a one-step Arrhenius chemistry model, are adopted to analyze the flow field structure. The results show that the bow shocks induced by symmetric-jets interacting with each other will achieve local detonation combustion. Influenced by the unstable shear layer behind the triple point, a large-scale vortex shedding is formed in the flow field, thus promoting the consumption of the unburned region. By comparing with the single-jet, it is found that the dual-jet initiation method can shorten the distance to complete initiation, but has little effect on the detonation overdrive degree. In addition, a study of the impact of jet size parameters on the symmetric-jet initiation further revealed that there is a critical value, above which the ignition decreases rapidly which is a significant advantage over single-jet. However, below this threshold, detonation initiation will rely on the energy generated by the collision of Mach stems formed at the walls, resulting in a slower ignition rate compared to a single-jet. Therefore, the use of the appropriate jet strength when using a symmetric-jet will result in a more desirable ignition velocity and a shorter distance to achieve detonation. Full article

(This article belongs to the Special Issue Aerospace Combustion Engineering)

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29 pages, 9198 KiB

Open AccessArticle

The Study of Electrical Energy Power Supply System for UAVs Based on the Energy Storage Technology

by Khac Lam Pham, Jan Leuchter, Radek Bystricky, Milos Andrle, Ngoc Nam Pham and Van Thuan Pham

Aerospace 2022, 9(9), 500; https://doi.org/10.3390/aerospace9090500 - 07 Sep 2022

Cited by 13 | Viewed by 9273

Abstract

Unmanned aerial vehicles (UAVs) are increasingly attracting investment and development attention from many countries all over the world due to their great advantages. However, one of the biggest challenges for researchers is the problem of supplying energy to UAVs to ensure they can [...] Read more.

Unmanned aerial vehicles (UAVs) are increasingly attracting investment and development attention from many countries all over the world due to their great advantages. However, one of the biggest challenges for researchers is the problem of supplying energy to UAVs to ensure they can operate for a longer time. Especially in the case of rotary wings, they consume more energy than other UAV types as the motors need to spend a lot of energy to operate in order to overcome the gravity of the earth. The article aims to research power supply, energy consumption on UAVs, and a method of taking advantage of external energy sources to provide power for the operation of UAVs and discuss UAVs’ structure, categories, and control. Two experiments were conducted separately to evaluate the energy consumption of UAVs and the energy conversion from external energy sources to electrical energy. A test bench was designed to evaluate and determine the maximum efficiency using regenerative braking mode. The measuring device was manufactured to measure the necessary parameters to calculate the energy consumption and performance of the system. Experimental numerical results show that energy conversion from external sources is one of methods that can help increase the flight time of the UAV. Full article

(This article belongs to the Special Issue Energy Efficiency of Small-Scale UAVs)

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31 pages, 11029 KiB

Open AccessArticle

Numerical Investigation of Nanofluid Flow over a Backward Facing Step

by Wen-Chung Wu and Ankit Kumar

Aerospace 2022, 9(9), 499; https://doi.org/10.3390/aerospace9090499 - 07 Sep 2022

Cited by 4 | Viewed by 2094

Abstract

Nanofluid flow over a backward facing step was investigated numerically at low Reynolds number and the heat transfer was analyzed and reported. Al₂O₃–H₂O nanofluids of different volume fractions (

φ

= 1–5%) were used as the material [...] Read more.

Nanofluid flow over a backward facing step was investigated numerically at low Reynolds number and the heat transfer was analyzed and reported. Al₂O₃–H₂O nanofluids of different volume fractions (

φ

= 1–5%) were used as the material with uniform heat flux (UHF) of 5000 W/m² at bottom wall for Reynolds number 200–600. The backward facing step of two geometries was investigated for two expansion ratios, 1.9432 and 3.5. The SIMPLE algorithm was used in the finite volume solver to solve the Naiver–Stokes equation. Temperature difference at inlet and boundaries, heat transfer coefficient, Nusselt number, coefficient of skin friction, and temperature contours were reported. The results show that when nanofluids are used, the coefficient of heat transfer and Nusselt number increased at all volume fractions and Reynolds number for both the expansion ratios. The coefficient of heat transfer at

φ

= 5% was higher by 9.14% and 9.68% than the pure water for ER = 1.9432 and ER = 3.5 at Re. 500. At

φ

= 5%, the outlet temperature for the duct decreased by 10 K and 5 K when compared to the pure water for ER = 1.9432 and ER = 3.5 at Re. 500. Coefficient of skin friction and outlet temperature decreased for both the volume fractions in both the expansion ratios. Full article

(This article belongs to the Special Issue Fluid Flow Mechanics (2nd Edition))

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20 pages, 4343 KiB

Open AccessArticle

Model Predictive Control-Based Attitude Control of Under-Actuated Spacecraft Using Solar Radiation Pressure

by Lei Jin and Yingjie Li

Aerospace 2022, 9(9), 498; https://doi.org/10.3390/aerospace9090498 - 07 Sep 2022

Cited by 1 | Viewed by 2657

Abstract

An attitude control strategy for an under-actuated spacecraft with two reaction wheels is proposed, using the active assistance of solar radiation pressure torque. By changing the rotation angles of the solar panels, the magnitude and direction of the solar radiation pressure torque is [...] Read more.

An attitude control strategy for an under-actuated spacecraft with two reaction wheels is proposed, using the active assistance of solar radiation pressure torque. By changing the rotation angles of the solar panels, the magnitude and direction of the solar radiation pressure torque is assumed to be adjustable in this paper. The attitude dynamic model of a rigid spacecraft with two reaction wheels and two solar panels is established and transformed into the form of a non-linear system. An integrated control scheme based on dual-mode model predictive control is proposed, which obtains the rotation speeds of the solar panels and the rotation accelerations of the reaction wheels directly as control quantities. Using this control method, not only are the constraints of rotation speeds and rotation angles of the panels satisfied, but also the robustness of the closed-loop system is ensured. The simulation results prove the validity of the proposed control method. Full article

(This article belongs to the Special Issue Latest Advancements in Aeronautics and Astronautics: Celebrating the 70th Anniversary of Beihang University)

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Aerospace, Volume 9, Issue 9 (September 2022) – 59 articles

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