CFD-Based Flutter Prediction for High Reynolds Number Flows with Free Boundary Layer Transition

Abstract

This paper introduces a local, correlation-based transition model used for CFD- based flutter predictions. The presented gamma transition model is based on the gamma transport equation of the gamma-Re_theta transition model. The model is calibrated for external aerodynamic flows in a low turbulence environment and is validated based on experimental data for moderate and high Reynolds numbers found in free flight. A steady 2D validation case, a steady 3D test case for comparison with the e^N method, an unsteady 2D validation test case, and an unsteady 2D test case for comparison with the e^N method are presented. In addition, the effect of a boundary layer transition on the flutter behavior of an airfoil in transonic flow at a free flight Reynolds number is demonstrated.