Study On Parameter And Impingement Characteristics Of Supercooled Water Droplet In Icing Conditions

Ice accretion is one of the biggest threat of the aircraft Lots of research to aviation accidents shows that even little of the ice accretion on the main part of the airplane will greatly influence its aerodynamic performance which can eventually cause to the decrease of operational ability and stability. To aero-engine, due to the ice accretion, air inlet of the engine could be blocking or the shape of the inlet could be transformed. If the big size ice impact on the fans or the blades, the mechanical structure of the engine will be damaged, which will almost lead to the flameout of the engine. So the study of aircraft icing and anti-icing can help to understand the reason of the ice accretion and the relationship between the ice and the accidents, which will give useful suggestion on methods and design of the aircraft anti-icing,In the icing environment, the research of parameters of supercooled droplets and the droplets impingement property are the basis of anti-icing experiment study. As a passive anti-icing method, the use of character of the super-hydrophobic surface has huge potential.Through the theoretical analysis、numerical calculation and the experiment, the research is carried on as the following:1) The mathematical model of parameters of the droplets in the icing tunnel is established by the calculation of the flow field of supercooled droplets and the air mixture. By comparison of different airflow velocity, temperature, original droplets temperature and relative humidity, the influence of the droplets temperature, velocity and volume is analyzed.2) Conduct a study of fuse or splash of the supercooled droplets when the droplets impact on the surface. Establish the energy model of droplets before and after the impingement. Whether the droplet will be fused or splash could be judged from the energy model which helps to show the realistic droplets collection coefficient of the airplane surface.3) Compare the flow regime on different surface and understand the influence of the surface to the fracture of water film by the air propulsion. Record the fracture position of the water film with different velocity, temperature and thickness and process a experiential correlation of the break-up of water film, which can be related with the icing accretion and anti-icing method.The present research involves three aspects:establishing the model of flow field of mixture of air and supercooled water, the fuse or splash of water in the course impingement and the influence of different surface to the water film fracture. The ice accretion may be variable affected by the factors above. As a result the environmental influence to the ice accretion on aeroengine and other main parts can be got, which can provide the theoretical suggestion to the anti-icing methods.