Computation of subsonic and transonic helicopter rotor flow using Euler equations

Abstract

A procedure for the computation of transonic steady and unsteady flow around helicopter rotors is presented. The algorithm is based on the Euler equations and allows the computation of anisotropic rotational flow and thus an implicitly accurate calculation of shocks. In addition the capturing of the rotor wake and the tip vortex is provided for arbitrary tip shapes. The code for the computation of steady, fully 3-D rotor flow is derived from the EUFLEX procedure originated by A. Eberle, that has successfully been applied to a lot of fixed wing configurations up to now. A finite-volume scheme based on the method of characteristic flux averaging solves the Euler equations formulated in the conservation form. The discretizatlon of the flow field is carried out in two different manners concerning the grid topology and the size of the physical domain. Calculations are presented for a non-lifting case and for a helicopter rotor in hover. The comparisons of the method in its present stage show good agreement with experimental data.