Icing numerical simulation based on improved lagrange method

Ice accretion leads to significant deterioration of aircraft aerodynamic performance and handling qualities. In this paper, ice accretion on NACA 0012 airfoil and multi-element airfoils are predicted using CFD method. Using a multi-block grid technique, we generate computational grids for the multi-element airfoils. A four-stage Runge-Kutta method is used to solve the droplet trajectory equation, a recursive box searching method is proposed to compute the position of the droplet. The method is efficient and robust. Compared with the traditional direct method, it obtains the same result and reduces computational time by one order of magnitude. Ice shape is determinated with assumption that all droplets freeze at their points of impact and the ice grows in the direction normal to the surface. The Reynolds-averaged Navier-Stokes equations are conducted to calculate the air flow field. A time-accurate, fully implicit LU-SGS method is used to solve the viscous flow problems. It uses a finite volume cell-centered formulation on structured grids and employs central space discretization with artificial dissipation for the residual computation, Spalart-Allmaras turbulence model was used in the numerical procedure. With the above methods and techniques, the computational results we got are in good agreement with the available experiments data, and show preliminarily that our method of icing predicted model and flow field numerical simulation is feasible.