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1 – 6 of 6J.‐Y. TRÉPANIER, M. REGGIO and D. AIT‐ALI‐YAHIA
An implicit method for the solution of transonic flows modelled by the time‐dependent Euler equations is presented. The method is characterized by a robust linearization for…
Abstract
An implicit method for the solution of transonic flows modelled by the time‐dependent Euler equations is presented. The method is characterized by a robust linearization for first‐ and second‐order versions of Roe's flux‐difference splitting scheme, an implicit treatment of the boundary conditions and the implementation of an adaptive grid strategy for global efficiency. The performance of the method is investigated for the GAMM test circular‐arc bump configuration and for the RAE 2822 aerofoil.
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Ngoc Anh Vu, Jae‐Woo Lee, Sangho Kim and Daniel Neufeld
Rotor performance analysis and design are complex due to the wide variation in flow characteristics. Design tools that can rapidly and accurately compute aerofoil data are needed…
Abstract
Purpose
Rotor performance analysis and design are complex due to the wide variation in flow characteristics. Design tools that can rapidly and accurately compute aerofoil data are needed for rotorcraft design and analysis purposes. The purpose of this paper is to describe a process which has been developed that effectively automates the generation of two‐dimensional (2D) aerofoil characteristics tables.
Design/methodology/approach
The process associates a number of commercial software packages and in‐house codes that employ diverse methodologies, including the Navier‐Stokes equation‐solving method, the high‐order panel method and Euler equations solved with the fully coupled viscous‐inviscid interaction (VII) method. The paper describes the development of a general automated generation method that extends from aerofoil shape generation to aerofoil characteristic analysis. The generated data are stored in C81 aerofoil characteristics tables for use in comprehensive rotorcraft analysis codes and rotor blade design. In addition, the methodology could be easily applied for fixed‐wing analysis and design, especially for transonic aircraft.
Findings
The method is demonstrated to achieve aerofoil characteristics quickly and accurately in automated process. Calculations for the SC1095 aerofoil section are presented and compared with existing experimental C81 data and previous studies.
Practical implications
The development of C81 tables is of interest to industry as they seek to update their airfoil tables as new designs. Automated processes to achieve this are helpful and applicable.
Originality/value
The paper presents an effective automated process to generate aerofoil characteristics tables quickly, and accurately.
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Francesco Casalini and Andrea Dadone
The viscous finite volume lambda formulation is presented. The suggested technique is apt to compute viscous flows with heat fluxes. The inviscid terms are evaluated by means of…
Abstract
The viscous finite volume lambda formulation is presented. The suggested technique is apt to compute viscous flows with heat fluxes. The inviscid terms are evaluated by means of the non‐conservative, very accurate upwind methodology, known as the finite volume lambda formulation. The diffusive terms, on the contrary, are approximated by a central scheme. Both methods are characterized by a nominal second order accuracy in space. Efficiency is enhanced by means of a multigrid technique which directly combines each grid level with each stage of an explicit multistage time integration technique. A laminar viscous flow about a NACA 0012 airfoil and a turbulent one about a RAE 2822 airfoil have been computed as well as the two‐ and three‐dimensional turbulent flows inside the Stanitz elbow. The computed numerical results are in very good agreement with well assessed published numerical or experimental results. The suggested multigrid technique allows significant work reductions for laminar as well as for turbulent flow computations.
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The compressible Navier‐Stokes equations are solved numerically for turbulent transonic aerospace applications on parallel computers. An Explicit Algebraic Reynolds Stress Model…
Abstract
The compressible Navier‐Stokes equations are solved numerically for turbulent transonic aerospace applications on parallel computers. An Explicit Algebraic Reynolds Stress Model (EARSM) models the turbulence. Expressing the EARSM as an extension of an eddy‐viscosity model makes the implementation straightforward in a flow solver with existing two‐equation eddy‐viscosity models. The k−ω transport equations are used as a platform for the model. The EARSM approach significantly improves the shock position for transonic flow over wings without substantial increase in computational cost. Industrial use of advanced flow modelling requires a short turn‐around time of computations. This is enabled through the use of parallel computers. To achieve good parallel performance the computational load has to be evenly distributed between the processors of the parallel computer. A heuristic algorithm is described for distributing and splitting the blocks of a structured multiblock grid for a good static load balance. Speed‐up results are presented for turbulent flow around a wing on a number of parallel platforms.
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Cornelia Grabe, Florian Jäckel, Parv Khurana and Richard P. Dwight
This paper aims to improve Reynolds-averaged Navier Stokes (RANS) turbulence models using a data-driven approach based on machine learning (ML). A special focus is put on…
Abstract
Purpose
This paper aims to improve Reynolds-averaged Navier Stokes (RANS) turbulence models using a data-driven approach based on machine learning (ML). A special focus is put on determining the optimal input features used for the ML model.
Design/methodology/approach
The field inversion and machine learning (FIML) approach is applied to the negative Spalart-Allmaras turbulence model for transonic flows over an airfoil where shock-induced separation occurs.
Findings
Optimal input features and an ML model are developed, which improve the existing negative Spalart-Allmaras turbulence model with respect to shock-induced flow separation.
Originality/value
A comprehensive workflow is demonstrated that yields insights on which input features and which ML model should be used in the context of the FIML approach
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Marc Guénot, Ingrid Lepot, Caroline Sainvitu, Jordan Goblet and Rajan Filomeno Coelho
The purpose of this paper is to propose a novel contribution to adaptive sampling strategies for non‐intrusive reduced order models based on Proper Orthogonal Decomposition (POD)…
Abstract
Purpose
The purpose of this paper is to propose a novel contribution to adaptive sampling strategies for non‐intrusive reduced order models based on Proper Orthogonal Decomposition (POD). These strategies aim at reducing the cost of optimization by improving the efficiency and accuracy of POD data‐fitting surrogate models to be used in an online surrogate‐assisted optimization framework for industrial design.
Design/methodology/approach
The effect of the strategies on the model accuracy is investigated considering the snapshot scaling, the design of experiment size and the truncation level of the POD basis and compared to a state‐of‐the‐art radial basis function network surrogate model on objectives and constraints. The selected test case is a Mach number and angle of attack domain exploration of the well‐known RAE2822 airfoil. Preliminary airfoil shape optimization results are also shown.
Findings
The numerical results demonstrate the potential of the capture/recapture schemes proposed for adequately filling the parametric space and maximizing the surrogates relevance at minimum computational cost.
Originality/value
The proposed approaches help in building POD‐based surrogate models more efficiently.
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