Numerical simulation of flowfield around micro helicopter rotors by solving incompressible Euler equations

Two significant technical barriers, which prevent correctly simulating the flow around micro air vehicles, are: (1) the difficulty in finding proper algorithm to solve the very low speed flow; (2) the difficulty in considering the very low Reynolds number. This paper is aimed at solving the first problem. We use a pseudo compressibility method to simulate the hovering flow field of micro-rotor. This method has been found to be an efficient method for obtaining the solution to the incompressible Euler equations. An O-H type grid around one blade is generated. Finite volume method with central discretization and Runge-Kutta time stepping is used. The technique of local time stepping, pressure damping and implicit residual smoothing are used to increase the convergence rate. The lift of the micro helicopter of centimeter scale^[7] is estimated using our computational code. The results show that, with a blade angle of attack of 15°, the micro helicopter can be lifted from the ground, which is consistent with the experimental results. We can conclude that the pseudo compressibility method is correct and reliable in simulating flow around the micro-rotors.