Boundary-layer transition measurements on Mach-scaled helicopter rotor blades in the rotating test facility Göttingen

Abstract

: Boundary-layer transition plays an important role in rotating blade aerodynamics affecting the performance of modern helicopter rotor blades such as low Reynolds number model rotors. However, advanced computational fluid dynamics (CFD) codes used for performance prediction purposes including modeling of this phenomenon on rotating blades are still in development and lack experimental data for validation purposes. This work presents spatially high resolved experimental boundary-layer transition data on the suction side of model helicopter blades in climb at relative radial positions between 0.4<r/R<1. Results are presented for various collective pitch settings and blade tip speeds (Mtip = 0.29- 0.58; Retip = 4.8 - 9.8x10^5). The study is intended to provide a preliminary data base for numeric validation purposes including boundary-layer transition of flows on rotating blades.