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Aerospace
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Fluid Flow Mechanics
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Fluid Flow Mechanics

A special issue of Aerospace (ISSN 2226-4310). This special issue belongs to the section "Aeronautics".

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 20873

Special Issue Editor

Dr. Pietro Catalano

E-Mail Website
Guest Editor
Fluid Mechanics Unit, Fluid Dynamic Model Lab., Italian Aerospace Research Centre, via Maiorise, 81043 Capua, CE, Italy
Interests: turbulence modelling for RANS and LES methods; transition modelling; numerical methods for flow control; drag reduction devices
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Authors are encouraged to submit technical papers in the area of theoretical, and computational fluid dynamics relevant to aerospace applications. The focus should be on applied research and advanced modelling and technology developments. Papers providing a comparison between reliable numerical results and certified experimental data are highly encouraged. The main topics that we expect to cover include:

  • Low-speed and low-Reynolds-number aerodynamics. Flows that exhibit laminar separation bubbles. Modelling issues connected to bubble length, pressure recovery in the re-attachment region, and turbulence levels inside the bubble.
  • Martian aerodynamics. Modelling issues related to the aerodynamics of vehicles operating in the Martian environment. The very low atmospheric pressure and density, together with low temperatures, means that flight in the Mars atmosphere is characterized by low Reynolds and high Mach numbers simultaneously—a circumstance that seldom happens on Earth. 
  • Flow control: actuators, applications, and flow physics. Techniques of flow control for avoiding/mitigating separation, reducing aerodynamic drag, and reducing aerodynamic noise.
  • Flow instability and laminar–turbulent transition. Modelling and simulation of flow instabilities. Models that predict boundary-layer transition for RANS equations. 
  • Hybrid RANS/LES models. Topics include turbulence modelling through hybrid RANS/LES methods, zonal and non-zonal approaches, gray-area mitigation issues, turbulence length scale and switching filter, and wall-modelled large-eddy simulation.   

Dr. Pietro Catalano
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Aerospace is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • turbulence modelling
  • computational fluid dynamics
  • laminar separation bubbles
  • separation
  • transition

Published Papers (6 papers)

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Research

22 pages, 20218 KiB  
Article
2D Numerical Study on the Flow Mechanisms of Boundary Layer Ingestion through Power-Based Analysis
by Peijian Lv, Mengmeng Zhang, Fei Cao, Defu Lin and Li Mo
Aerospace 2022, 9(4), 184; https://doi.org/10.3390/aerospace9040184 - 30 Mar 2022
Cited by 1 | Viewed by 1885
Abstract
This paper aims to establish an approach of power bookkeeping in a numerical study. To study the process of power conversion coursed in the flow field, the methodology employs a power-based analysis to quantify power terms. This approach is examined in a simulation [...] Read more.
This paper aims to establish an approach of power bookkeeping in a numerical study. To study the process of power conversion coursed in the flow field, the methodology employs a power-based analysis to quantify power terms. This approach is examined in a simulation of jet flow and then applied to the cases of an isolated actuator disc and an isolated flat plate. Eventually, a numerical simulation is carried out for the boundary layer ingestion (BLI) case that integrates the flat plate and a wake-filling actuator disc. This study quantitatively discusses the mechanisms of BLI under the conditions of laminar and turbulent flow. The proposed power-based analysis might offer insights for the aircraft aerodynamic design using favorable airframe propulsion integration. Full article
(This article belongs to the Special Issue Fluid Flow Mechanics)
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25 pages, 14978 KiB  
Article
The Control of Corner Separation with Parametric Suction Side Corner Profiling on a High-Load Compressor Cascade
by Xiangjun Li, Jiezhong Dong, Hua Chen and Huawei Lu
Aerospace 2022, 9(3), 172; https://doi.org/10.3390/aerospace9030172 - 21 Mar 2022
Cited by 4 | Viewed by 2191
Abstract
Nowadays, with the increase of the thrust-to-weight ratio of the aero engines, the high aerodynamic load has made corner separation an issue for axial compressors. The complex three-dimensional flow field makes it challenging to suppress the corner separation, especially considering the performance at [...] Read more.
Nowadays, with the increase of the thrust-to-weight ratio of the aero engines, the high aerodynamic load has made corner separation an issue for axial compressors. The complex three-dimensional flow field makes it challenging to suppress the corner separation, especially considering the performance at multi-working conditions. To suppress the corner separation and reduce loss, the investigation in this paper proposed a new parametric suction side corner profiling method, which includes few variables but enables the flexible variation of the shape. A bi-objective auto-optimization design process for the corner profiling was carried out on a high-load linear compressor cascade, with the companion of end wall and blade profiling. The aim was to investigate the effective flow control rules for the corner separation and practical design guidelines for its geometry under multiple working conditions. The numerical results identified that the suction side corner profiling brings a much more dominant effect to corner separation than end wall profiling and blade profiling. The most critical flow control rule is to accelerate the climbing second flow on the bottom of the suction surface to suppress the reverse trend of the boundary layer and further relieve the corner separation. In addition, the design point and near-stall point have different well-fitting thicknesses and axial positions. A medium value between the design and near-stall well-fitting parameters will make the suction side corner profiling a best-matching case for a medium inflow condition and adequate performance at a range of conditions. Full article
(This article belongs to the Special Issue Fluid Flow Mechanics)
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18 pages, 7815 KiB  
Article
Improved Supersonic Turbulent Flow Characteristics Using Non-Linear Eddy Viscosity Relation in RANS and HPC-Enabled LES
by Kalyani Bhide, Kiran Siddappaji, Shaaban Abdallah and Kurt Roberts
Aerospace 2021, 8(11), 352; https://doi.org/10.3390/aerospace8110352 - 18 Nov 2021
Cited by 7 | Viewed by 2611
Abstract
A majority of the eddy viscosity models for supersonic turbulent flow are based on linear relationship between Reynolds stresses and mean strain rate. The validity of these models can be improved by introducing non-linearity in relation as RANS models offer advantages in terms [...] Read more.
A majority of the eddy viscosity models for supersonic turbulent flow are based on linear relationship between Reynolds stresses and mean strain rate. The validity of these models can be improved by introducing non-linearity in relation as RANS models offer advantages in terms of reduced turnaround times typical of industry applications. With these benefits, the present work utilizes quadratic constitutive relation (QCR) with Menter’s k omega SST model to characterize the flowfield of rectangular jets. The sensitivity of this model with QCR, weighted towards diffusion, dissipation, and a combination of both, is addressed. Viscous large eddy simulations (LES) with WALE subgrid scale models are employed for qualitative comparisons using a commercial solver. Massively parallel LES are enabled by the new in-house 1088-core computing cluster at the University of Cincinnati and are also used for benchmarking. The nearfield results are validated with available experimental data and show good agreement in both fidelities. Flow characteristics, including the shear layer profiles, Reynolds stresses, and turbulence kinetic energy (TKE) and its production are compared. LES reveal higher TKE production in the regions with highest Reynolds stresses. It is comparatively lower in QCR RANS. As a special case of TKE analysis in jets, a preliminary investigation of retropropulsion is outlined for rectangular nozzles for the first time. Improved flow behavior by implementation of a non-linear relationship between Reynolds stresses and mean strain rate is demonstrated. Full article
(This article belongs to the Special Issue Fluid Flow Mechanics)
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20 pages, 6206 KiB  
Article
A Study of Recirculating Flow Fields Downstream of a Diverse Range of Axisymmetric Bluff Body Geometries Suitable for Flame Stabilization
by Georgios Paterakis, Konstantinos Souflas, Andreas Naxakis and Panayiotis Koutmos
Aerospace 2021, 8(11), 339; https://doi.org/10.3390/aerospace8110339 - 10 Nov 2021
Viewed by 1980
Abstract
This work investigates the non-reacting time averaged and fluctuating flow field characteristics downstream of a variety of axisymmetric baffles, operating in combination with an upstream double-cavity premixer arrangement. The study aims to broaden knowledge with respect to the impact of different bluff body [...] Read more.
This work investigates the non-reacting time averaged and fluctuating flow field characteristics downstream of a variety of axisymmetric baffles, operating in combination with an upstream double-cavity premixer arrangement. The study aims to broaden knowledge with respect to the impact of different bluff body shapes, leading and trailing edge flow contours, blockage ratios and incoming flow profiles impinging on the bluff body, on the development and properties of the downstream recirculating wake. Particle Image Velocimetry (PIV) measurements have been employed to obtain the mean and turbulent velocity fields throughout the centrally located recirculation zone and the adjacent developing toroidal shear layer. The results are helpful in demarcating the cold flow structure variations in the near wake of the examined baffles which support and, to some extent, determine the flame anchoring performance and heat release disposition in counterpart reacting configurations. Additionally, such results could also assist in the selection of the most suitable flame stabilization configuration for fuels possessing challenging combustion behavior such as multi-component heavier hydrocarbons, biofuels, or hydrogen blends. Full article
(This article belongs to the Special Issue Fluid Flow Mechanics)
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19 pages, 4938 KiB  
Article
Numerical Study of the Lift Enhancement Mechanism of Circulation Control in Transonic Flow
by Ye Chen, Zhongxi Hou, Xiaolong Deng, Zheng Guo, Shuai Shao and Boting Xu
Aerospace 2021, 8(11), 311; https://doi.org/10.3390/aerospace8110311 - 20 Oct 2021
Cited by 3 | Viewed by 1837
Abstract
The lift of an aircraft can be effectively enhanced by circulation control (CC) technology at subsonic speeds, but the efficiency at transonic speeds is greatly decreased. The underlying mechanism of this phenomenon is not fully understood. In this study, Reynolds averaged Navier—Stokes simulation [...] Read more.
The lift of an aircraft can be effectively enhanced by circulation control (CC) technology at subsonic speeds, but the efficiency at transonic speeds is greatly decreased. The underlying mechanism of this phenomenon is not fully understood. In this study, Reynolds averaged Navier—Stokes simulation with k−ω shear stress transport model was utilized to investigate the mechanism of lift enhancement by CC in transonic flow. For validation, the numerical CC results were compared with the NASA experimental data obtained for transonic CC airfoil. Thereafter, the RAE2822 airfoil was modified with a Coanda surface. The lift enhancement effects of CC via steady blowing with different momentum coefficients were tested at Ma=0.3 and 0.8 at α=3∘, and various fluid mechanics phenomena were investigated. The results indicate that the flow structure of the CC jet is insensitive to the incoming flow conditions because of the similarity to the local static pressure field around the trailing edge of the airfoil. Owing to the appearance of shockwaves on the airfoil surface in the transonic regime, the performance of the CC jet is restricted to the trailing edge of the airfoil. Transonic CC achieved a slight improvement in aerodynamic performance owing to a favorable shift in the shockwave pattern and accelerated flow in the separation region on the airfoil surfaces. Revealing the mechanism of lift enhancement of CC in the transonic regime can facilitate the rational design of new fluidic actuators with high activity and expand the potential applications of CC technology. Full article
(This article belongs to the Special Issue Fluid Flow Mechanics)
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25 pages, 10799 KiB  
Article
A Parametric Blade Design Method for High-Speed Axial Compressor
by Hengtao Shi
Aerospace 2021, 8(9), 271; https://doi.org/10.3390/aerospace8090271 - 18 Sep 2021
Cited by 5 | Viewed by 7509
Abstract
The blade geometry design method is an important tool to design high performance axial compressors, expected to have large design space while limiting the quantity of design variables to a suitable level for usability. However, the large design space tends to increase the [...] Read more.
The blade geometry design method is an important tool to design high performance axial compressors, expected to have large design space while limiting the quantity of design variables to a suitable level for usability. However, the large design space tends to increase the quantity of the design variables. To solve this problem, this paper utilizes the normalization and subsection techniques to develop a geometry design method featuring flexibility and local adjustability with limited design variables for usability. Firstly, the blade geometry parameters are defined by using the normalization technique. Then, the normalized camber angle f1(x) and thickness f2(x) functions are proposed with subsection techniques used to improve the design flexibility. The setting of adjustable coefficients acquires the local adjustability of blade geometry. Considering the usability, most of the design parameters have clear, intuitive meanings to make the method easy to use. To test this developed geometry design method, it is applied in the design of a transonic, two flow-path axial fan component for an aero engine. Numerical simulations indicate that the designed transonic axial fan system achieves good efficiency above 0.90 for the entire main-flow characteristic and above 0.865 for the bypass flow characteristic, while possessing a sufficiently stable operation range. This indicates that the developed design method has a large design space for containing the good performance compressor blade of different inflow Mach numbers, which is a useful platform for axial-flow compressor blade design. Full article
(This article belongs to the Special Issue Fluid Flow Mechanics)
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