Rotor Performance and Turbulent Wake Simulations of a Scaled Helicopter Rotor in Hover Using Wall-Modeled Large-Eddy Simulations

Abstract

A scaled helicopter rotor in hover is studied using wall-modeled large-eddy simulations (WMLES). Performance is evaluated for three thrust conditions at varying grid resolutions and validated with experimental measurements. Capturing the effects of the laminar-turbulent transition over the blade, and the subsequent impact on blade forces, poses a significant challenge for the equilibrium wall model. Results indicate that a mesh with around two grid points in the turbulent boundary layer predicts forces that indicate fully turbulent flow over the blade. Meshes with around seven grid points in the turbulent boundary layer can capture some transitional impact on blade forces, despite not accurately predicting transition location. Further confirmation of viscous force impact on rotor loads was evaluated with simulations using a blowing-suction trip to force transition and a wall-model sensor to act as a crude transition model.