Numerical Simulations for the Flowfield of Helicopter Rotors in Hovering Based on High-Order Upwind Flux-Difference Splitting Scheme

In order to reduce effectively the numerical dissipation of the rotor wake vorticity induced by Jameson’s second-order cell-centered finite volume approach,with the combination of the third-order upwind scheme (MUSCL) and flux-difference splitting scheme,a numerical method based upon the solution of three-dimensional Reynolds-average N-S equations has been developed to simulate the flowfield around a lifting rotor in hovering.To incorporate the important effects of the rotor wake,the far-field boundary condition derived from the rotor momentum theory and the cyclic boundary condition have been used.The embedded grids methodology was adopted so as to weaken the numerical dissipation of the wake and be easy to apply the above mentioned boundary conditions.Several cases of the blade surface pressure distribution have been calculated using the present method and the second-order center difference.The calculated results were validated by comparing with available experimental data.Then flowfield simulations under rotor hovering conditions were performed for three different blade tip planforms.The numerical results demonstrate that the swept tips can suppress supercritical flow.Additionally, the vorticity contours were computed and the characteristics of distorted rotor wake were analyzed.It is shown that the present method can effectively reduce the numerical dissipation of the rotor wake.