The mutilgrid method in Euler equation computation about a helicopter rotor in hover

An effective multigrid method has been developed to compute the Euler solution for a helicopter rotor in hover using different space discrete schemes. The reasons of using multigrid method are the following: the flow near the hub is incompressible flow, which can slow the convergence; for the most part, the net flow velocity at the plane of the rotor and in the rotor wake itself is comprised of the velocities induced by the wake especially by the tip vortices. So the full development of wake is very important for the convergence of the flow field, but it require a long time in the numerical simulation. Accordingly, the application of acceleration measure is very useful for the rotor computation. In this Euler solver, Roe's FDS scheme and Jameson finite volume methods are used in space solution and five-step Runge-Kutta methods are used in time solution. A three-level V cycle multigrid method is implemented in a transonic flow computation. Numerical results show that the present multigrid method can speed up the rotor flow convergence rate remarkably and no matter what is in shock-capturing or computation accuracy Roe's FDS scheme is better than JST scheme.