Prediction Of The Laminar-To-Turbulent Transition Position On A Helicopter Rotor In Forward Flight

Abstract

This paper proposes to evaluate the capabilities of different turbulence transition models with CREATETM-AV Helios and elsA CFD codes to reproduce the boundary layer transition evolution on a helicopter rotor blade in forward flight. Transition models based on transport equations such as Amplification Factor Transport model and Langtry-Menter model provide good agreements with the experimental measurements, while models based on semi-empirical boundary layer criteria show more discrepancies. The sensitivity of the prediction with respect to the numerical setup is analyzed. It shows that the grid resolution and the blade deformation have a noticeable effect on the transition position, while the fuselage has a minor influence. The strategy used to compute the transition position has to be set up carefully as it can significantly impact the results. With the same Langtry-Menter model, Helios and elsA shows similar predictions, but Helios provides a better agreement with experiments that can be partially related to the blade deformation.