Evaluation of Higher Order Improvement of Unstructured Schemes for Helicopter Rotor Simulations

Abstract

A high-order improvement to an unstructured viscous CFD solver is evaluated and applied to the computation of helicopter rotors in hover and forward flight. The high-order improvement is achieved by reconstructing flow variables at interface of each control volume through high-order polynomial approximations. The reconstructed interface variables are used as the basis values to evaluate the high-order fluxes on the sub-faces of each interface of the control volume using a radial basis function interpolation. The improvement on the unstructured scheme is evaluated for an inviscid unsteady vortex travelling with a free stream flow for the observed order of accuracy. The high-order improvement method is also applied to compute a realistic helicopter rotor in hover and forward flight. Numerical studies indicate that the current high-order improvement is effective in preserving the vortex strength generated by helicopter blades and thus improves the numerical accuracy of predictions.