Code-to-Code Comparison of CFD/CSD Simulation for a Helicopter Rotor in Forward Flight

Two unsteady Reynolds-averaged Navier-Stokes solvers are used to compute the rotor airloads on the UH-60A rotorcraft at several flight conditions across the flight envelope. One code, OVERFLOW, solves the flow equations using either structured grids, or a combination of structured and Cartesian grids. The other solver, FUN3D, uses unstructured grids. Both flow solvers are coupled to the same rotorcraft comprehensive code (CAMRAD II) in order to account for trim and aeroelastic deflections, and both utilize the same loose coupling scheme to transfer data between the flow solver and the comprehensive code. In the process of performing the code-to-code comparison, several small but important details are examined that may sometimes be overlooked when comparing results from rotorcraft simulations using different codes. Computed normal force, pitching moment, and chord force are compared between codes, and also with flight data.