Turbulence Simulation and Advanced Theoretical, Experimental, and Computational Method Development Relevant to External Aerodynamics, Separation, and Transitional Flows

A special issue of Aerospace (ISSN 2226-4310).

Deadline for manuscript submissions: closed (31 July 2020) | Viewed by 25127

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Guest Editor
Centre for Computational Engineering Sciences, School of Aerospace, Transport and Manufacturing, Cranfield University, Cranfield MK43 0AL, Bedfordshire, UK
Interests: computational fluid dynamics (CFD); flight physics; vehicle aerodynamics; on-road vehicle dynamics; renewable energy
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Special Issue Information

Dear colleagues,

Simulation of turbulent flows is an interdisciplinary research field that brings together development and knowledge in conjunction with mathematical and computational physics, numerical methods, computer science, computational fluid dynamics (CFD), combustion, experimental methods, engineering fluid mechanics, and engineering applications. Since there is no ultimate solution for modeling complex turbulent flow problems, therefore, the present Special Issue is interested in recent theoretical, experimental, and computational method developments relevant to external aerodynamics, separation, and transitional flows. Advanced and new closure models for the solution of unsteady and stationary Reynolds- and Favre-Averaged Navier-Stokes (URANS/RANS, UFANS/FANS) equations, the solution of Partially-Averaged Navier-Stokes (PANS) equations for turbulence, Reynolds Stress Models (RSM), classical and Implicit Large Eddy Simulation techniques (LES/ILES), Detached Eddy Simulations (DES)-coupling RANS and LES models, hybrid approaches, and computationally expensive Direct Numerical Simulations (DNS) are particularly welcome. The development of anisotropic turbulence models for separation flows, as well as the theoretical and practical aspects of the development of Galilean invariant transitional closure models, is of central interest to the current Special Issue. It is important note that the Galilean invariance of transitional models is a challenging subject nowadays. Authors are also encouraged to focus on complex three-dimensional turbulent flow problems, which involve the application of validation and verification techniques; accordingly, the quantification of theoretical and experimental uncertainties can be addressed.

Dr. László Könözsy
Guest Editor

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Keywords

  • three-dimensional turbulent flows
  • external aerodynamics
  • separation flows
  • transitional flows
  • anisotropic turbulence
  • Galilean invariance
  • aerospace applications

Published Papers (3 papers)

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Research

21 pages, 13056 KiB  
Article
Effect of Local Grid Refinement on Performance of Scale-Resolving Models for Simulation of Complex External Flows
by Amne ElCheikh and Michel ElKhoury
Aerospace 2019, 6(8), 86; https://doi.org/10.3390/aerospace6080086 - 06 Aug 2019
Cited by 9 | Viewed by 4410
Abstract
Numerical simulations are crucial for fast and accurate estimations of the flow characteristics in many engineering applications such as atmospheric boundary layers around buildings, external aerodynamics around vehicles, and pollutant dispersion. In the simulation of flow over urban-like obstacles, it is crucial to [...] Read more.
Numerical simulations are crucial for fast and accurate estimations of the flow characteristics in many engineering applications such as atmospheric boundary layers around buildings, external aerodynamics around vehicles, and pollutant dispersion. In the simulation of flow over urban-like obstacles, it is crucial to accurately resolve the flow characteristics with reasonable computational cost. Therefore, Large Eddy Simulations on non-uniform grids are usually employed. However, an undesirable accumulation of energy at grid-refinement interfaces was observed in previous studies using non-uniform grids. This phenomenon induced oscillations in the spanwise velocity component, mainly on fine-to-coarse grid interfaces. In this study, the two challenging test cases of flow over urban-like cubes and flow over a 3-D circular cylinder were simulated using three different scale-resolving turbulence models. Simulations were performed on uniform coarse and fine grids on one hand, and a non-uniform grid on the other, to assess the effect of mesh density and mesh interfaces on the models’ performance. Overall, the proposed One-Equation Scale-Adaptive Simulation (One-Equation SAS) showed the least deviation from the experimental results in both tested cases and on all grid sizes and types when compared to the Shear Stress Transport-Improved Delayed Detached Eddy Simulation (IDDES) and the Algebraic Wall-Modeled Large Eddy Simulation (WMLES). Full article
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18 pages, 5637 KiB  
Article
Investigation of the Trailing Edge Modification Effect on Compressor Blade Aerodynamics Using SST k-ω Turbulence Model
by Mongkol Kaewbumrung, Worapol Tangsopa and Jatuporn Thongsri
Aerospace 2019, 6(4), 48; https://doi.org/10.3390/aerospace6040048 - 25 Apr 2019
Cited by 16 | Viewed by 6329
Abstract
A gas turbine power plant in Thailand had the problem of compressor blade fracture in Stages 6–8, which was caused by housing damage. This gas turbine has a total of 15 stages. The housing damage reduced the lifetime of blades to an unacceptable [...] Read more.
A gas turbine power plant in Thailand had the problem of compressor blade fracture in Stages 6–8, which was caused by housing damage. This gas turbine has a total of 15 stages. The housing damage reduced the lifetime of blades to an unacceptable level. This article shall report the solution and outcomes. Three-dimensional (3D) compressor blade models in the problematic stages were prepared by a 3D scanning machine to find a solution based on computational fluid dynamics (CFD), and then were completed for simulation by adding Stages 5 and 9 to become a multi-stage axial model. The latter models were modified by trimming the trailing edge by 1-, 5-, and 10-mm. Using ANSYS CFX R19.2 software, the CFD results of the trailing edge modification effect on flow using the shear stress transport (SST) k-ω turbulence model revealed aerodynamics inside the problematic stages both before and after blade modifications. Modifying the blade by 5 mm was suitable, because it had lesser effects on aerodynamic parameters: pressure ratio, drag, and lift coefficients, when compared to the modification of 10 mm. The larger the modification, the greater the effect on aerodynamics. The effects on aerodynamics were intensified when they were modified by 10 mm. The validation of base line blades was conducted for the overall compressor parameters that were compared with the measurable data. These results were accepted and gave positive feedbacks from engineers who practically applied our reports in a real maintenance period of gas turbine. Full article
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20 pages, 6894 KiB  
Article
Vortex Dynamics Study of the Canard Deflection Angles’ Influence on the Sukhoi Su-30-Like Model to Improve Stall Delays at High AoA
by Sutrisno, Tri Agung Rohmat, Setyawan Bekti Wibowo and Sigit Iswahyudi
Aerospace 2019, 6(2), 12; https://doi.org/10.3390/aerospace6020012 - 01 Feb 2019
Cited by 5 | Viewed by 13353
Abstract
The maneuverability of the Sukhoi Su-30 at very high angles of attack (AoA) was remarkably appealing. Canard angle, in cooperation with aircraft wing, created a flow pattern whereby, in that position, the fighter still had as much lifting force as possible in order [...] Read more.
The maneuverability of the Sukhoi Su-30 at very high angles of attack (AoA) was remarkably appealing. Canard angle, in cooperation with aircraft wing, created a flow pattern whereby, in that position, the fighter still had as much lifting force as possible in order not to stall. The behavior of changing canard angle configuration played an essential role in creating the strong vortex core so that it could delay the stall. The study of vortex dynamics at canard deflection angle gave an essential function in revealing the stall delay phenomenon. In this study, one could analyze the flow patterns and vortex dynamics ability of the Sukhoi Su-30-like model to delay stall due to the influence of canard deflection. The used of water tunnel facilities and computational fluid dynamics (CFD) based on Q-criterion has obtained clear and detailed visualization and aerodynamics data in revealing the phenomenon of vortex dynamics. It was found that between 30° and 40° canard deflection configurations, Sukhoi Su-30-like was able to produce the most robust flow interaction from the canard to the main wing. It was clearly seen that the vortex merging formation above the fighter heads was clearly visible capable of delaying stall until AoA 80°. Full article
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