Numerical Study Of 3D Ice Accretion On Aircraft Wing And Its Aerodynamic Effect Under Thermal Anti-ice

When airplanes pass through clouds which contain supercooled water droplets,ice will accrete on the surfaces of the upwind components.Rime ice,glaze ice and mixed ice are the common types of ice accretion.Ice layer destroys the aerodynamic shape of components and the aerodynamic characteristics of the engine inlet flow field,it causes the stalling of aircraft and the surge of engine.In order to reduce the danger of ice accretion,heat flux is generally provided to the front ice accretion zone.On this occasion,it is difficult for all the supercooled water to freeze in the thermal anti-ice zone.The water film would flow downstream and produce ridge ice.Ridge ice has firm structure and poor aerodynamic shapes,and it causes a more serious influence on the aerodynamic performance of airplanes.The process of the unfrozen water film flow is inevitably accompanied by evaporation,which affects the mass exchange and heat exchange,thus it causes further influence on the thickness and coverage of the ice layer.On the one hand,the evaporation reduces the thickness and coverage of the water film,on the other hand,the evaporation enhances the heat exchange between the surface of the water film and the flow field,which is a more obvious phenomenon under the condition of thermal anti-ice.In this paper,the influence of evaporation on the ice accretion process is considered,and the evaporation and the surface temperature of water film are coupled.Under the condition of thermal anti-ice,the mathematical model and calculation method of the three-dimensional icing model are developed,and the corresponding program is added.Afterwards,the glaze ice and ridge ice on the airfoil are simulated and compared with experimental results,and then the rationality of the threedimensional icing model is validated.Based on the three-dimensional icing model,this paper numerically simulates the ice accretion processes under the different conditions of thermal anti-ice,and the different ice shapes are demonstrated with heat flux changing.Afterwards,the influence on aerodynamic characteristics caused by ice shapes and icing time is obtained,and the corresponding water film flow states are analyzed.The numerical results show that with the increase of heat flux,the ice shape on the airfoil gradually transitions from glaze ice to ridge ice,and water film exist finally.Furthermore,both glaze ice and ridge ice would decrease the lift and increase the drag,this change would be worse over icing time.And compared to the glaze ice,the ridge ice is more harmful.This paper also performs a simple single-zone anti-ice design on the ice accretion example,and the corresponding relationship between water film length and heat flux is obtained,therefore the op-timal thermal anti-ice zone is found.The numerical results show that it is more economical to anti-ice on the wet surface than the dry surface of airfoil.Furthermore,the water film length will gradually decrease with the increase of heat flux,and the minimum anti-ice power is obtained when the water film length overlap impingement area.The three-dimensional icing model improved in this paper can simulate the ice accretion processes under the conditions of adiabatic or thermal anti-ice,and provide technical support for aircraft ice prediction and thermal anti-ice design.