Comparison of Computational Fluid Dynamics Analysis and Flight Test for Coaxial Contra-Rotating Rotor Helicopter

The Kamov Ka-32 with coaxial contra-rotating rotor blades has been known as one of the best helicopter for firefighting operations because it can carry the largest amount of water within the fuselage. Complex unsteady flow fields and the interference effects between the rotor blades and fuselage were investigated using an overset grid-based computational fluid dynamics (CFD) method. The governing unsteady Reynolds-averaged Navier-Stokes (RANS) equations were discretized spatially using a finite volume method. An implicit unsteady flow solver and the the Shear Stress Transport (SST) k-ω turbulence model are used. Boundary information was exchanged between overset and neighboring meshes using a weighted interpolation method. The unstructured overset grid technique are utilized in order to maximize the number of cells in the area of interest while minimizing cells in the far field. The complete configuration of Ka-32 helicopter with coaxial contra-rotating rotor blades are analyzed and numerical results are compared with actual flight test data.