CFD Prediction of Air Flow Past a Full Helicopter Configuration

The present study is one of the first attempts to exploit the GOAHEAD data base to perform a code-to-code evaluation on complete helicopter aerodynamics. The numerical results of two GOAHEAD partners, the German Aerospace Center (DLR) and Politecnico di Milano (PoliMi) are presented and compared to experimental measurements. The study also addresses an evaluation of two different approaches to predict helicopter flows. The first, applied by DLR, accounts for rotor trim and elastic effects by weak fluid-structure coupling. The PoliMi approach, on the other hand, enforces a prescribed kinematics, taken directly from the experiment, on a rigid blade. The simulations refer to a complete helicopter wind-tunnel model, featuring a scaled NH90 fuselage, the ONERA 7AD main rotor, a scaled BO105 tail rotor, a rotor hub and a pylon, all located inside the 8 m × 6 m test section of the DNW low-speed wind tunnel. The flight conditions correspond to cruise flight at Ma=0.204 and fuselage attitude α=-2.5°. The comparisons demonstrate the capability of present unsteady RANS solvers to predict flow fields around complete helicopters.