Improved Two-Dimensional Dynamic Stall Prediction with Structured and Hybrid Numerical Methods

Abstract

The paper will discuss the latest results of a comprehensive validation activity on the numerical methods TAU and elsA, conducted with respect to dynamic stall applications. The work has been performed in the joint German/French project SIMCOS (Advanced Simulation and Control of Dynamic Stall) in the frame of the DLR/ONERA cooperation on helicopter technologies. The validation was conducted by two-dimensional unsteady RANS simulations on two dynamic stall test cases for the rotor blade airfoil OA209. Test case DS1 measured in the French ONERA-F2 wind tunnel represents a low speed deep dynamic stall case at M = 0.16, Re = 1.8e6, α = 13° ± 5°, and ω* = 0.1 (ω* = 2πfc/v_∞). Test case DS2 measured in the German DNW-TWG wind tunnel represents a high speed deep dynamic stall case at M = 0.31, Re = 1.16e6, α = 13° ± 7°, and ω* = 0.1. The numerical methods used were the ONERA in-house flow solver elsA and the DLR in-house flow solver TAU. While the elsA code is a structured solver, the TAU code is an unstructured solver using hybrid grids. Simulations were performed with respect to the investigation of the influence of temporal resolution, grid characteristics, turbulence modeling, and transition prediction on the results of the codes. The results of the individual investigations will be discussed and the numerical methods, as well as turbulence and transition modeling from TAU and elsA will be compared.