Investigation Of Mathematic Model And Calculational Methodology For 3D Ice Accretion On The Up-wind Surfaces

When the aircraft flys into the clouds with supercooled water droplets, ice accretion occurs on the up-wind surfaces, such as airfoil and engine-inlet. The ice on the airfoil leads to lift decrease and drag increase. The ice on the engine-inlet leads to thrust lost and even engine damage. All these reduce the safty of the flight. So, much attention has been paid on the study of the ice accretion on up-wind surfaces. The simulation of 2D ice accretion has been well done while the 3D simulation is just under research in the abroad. Many papers about 2D icing simulation have been published while the 3D icing simulation is just at the beginning in our country. The current research aims at developing an icing model and corresponding calculational methodology for 3D ice accretion, and also developing a 3D ice simulating program.Firstly, a 3D icing model and the simulating program is developed. The model concerns three cases: rime ice, glaze ice and no ice. In this model, the control equations for the shallow water film flow are built. So the water flow is numerically simulated based on the equations. This is a big progress compared to the Messinger icing model in which the water flow is simply treated. The ice accretion on the corner of two intersecting surfaces is also concerned in the current model. The 3D ice simulating program is developed based on the icing model. The program can estimate which kind of ice will accrete uder different climate conditions. And it can provide the ice thickness and the informations of water flow at different time.Secondly, a calculational methodology for the 3D ice simulation is developed. In this methodology, the water collection efficiency, the ice accretion and water flow on the ice layer are simulated with the program developed in this paper. The grid genetation, two-phase flow computation and ice surface construction are done with ICEM, CFX and UG respectively. The ice simulation process, grid generation-twophase flow computation-ice accretion and water flow simulation-ice surface construction, is completed with the program and softwares. So the 3D icing simulation efficiency is enhanced.Thirdly, some improvements are added into the ice simulating program based on some detailed research about the heat convection between air flow and ice layer, the conduction between substrate and ice layer, the water flow in the reback area, the"front"of the water film, et al.Then, many icing examples are simulated and the results are compared to that provided in the published papers. Good agreement proves the icing model is logical, the calculational methodology is feasible, and the program developed in this paper is credible.Finally, the ice accretion on three simplified structures is numerically simulated. These three structures simulate the airfoil-the body of aircraft, the airfoil tip, the fairing and its strut in the engine-inlet respectively. The primary results show the characteristics of icing on these up-wind surfaces. The simulation work also shows the 3D ice simulating ability of the program developed in this paper. The research in this paper provides an approach for predicting the ice on the up-wind surfaces of the aircraft/aero-engine.