Numerical And Experimental Study On Deformation Characteristics Of Water Droplets’ Movement

Deformation of moving water droplets has always been one of the key issues in the field of multiphase flow and aircraft icing.Numerical simulation and experimental research on the movement process of water droplets have far-reaching significance.In this thesis,the numerical simulation of water-gas multiphase flow with large density contrast is carried out based on level set method and the experiments of water droplets moving towards the airfoil are conducted in wind tunnel.The main contents are summarized as follows:The research background of the deformation of water droplets is discussed firstly.The characteristic of aircraft icing under supercooled large droplets conditions and the complexity of watergas multiphase flow with large density contrast are summarized.Then the level set method for capturing fluid interface and the reinitialization method is introduced in the second chapter followed by numerical simulation of several typical interface motion problems.The numerical method which can be used to solve multiphase flow with large density contrast based on the level set method is established in chapter three,and the non-physics oscillation due to large density contrast is eliminated by smoothing the density at the interface within a few grids.The projection method for variable-density flow is used to solve the two-phase flow field uniformly,and the surface tension is coupled into the solution of the flow field.And this method is applied to the simulation of droplets’ motion towards the airfoil by introducing the conception of droplet and airfoil calculation domain.The experimental research on the motion of water droplets towards airfoil is carried out.The high-speed photography system is used to photograph the movement of single water droplet in the wind tunnel.The post-processing method of droplet image is given,and the experimental results are compared with the ones simulated by the method from chapter three.The work of this paper is summarized at last,and the future working direction of numerical simulation and experimental research is given.