Low Power Superhydrophobic Electrothermal Skin And Its Anti-Icing Performance

Recently,with the rapid development of aviation industry in China,the problem of aircraft icing has been focused particularly.The icing on the plane is a serious threat to flight safety.Traditional anti-icing technologies,such as air bags,hot gas,electric heat and others,cannot meet the development needs of future aircraft.The current research indicates that the superhydrophobic surface has the ability of anti-icing to some extent.However,it is not ideal that simply relying on superhydrophobic surface for anti-icing,because icing delay time is relatively limited.Once the superhydrophobic surface is frozen,icing will increase rapidly.Here,a low energy anti-icing skin is proposed by combined a polyimide(PI)superhydrophobic surface and an electrothermal film.The related performances and ice wind tunnel test are studied.This article mainly includes the following contents:(1)For anti-icing demand of a UAV,the thermal flow of the airfoil surface was analyzed.According to the special anti-icing conditions on the superhydrophobic surface,the main heat flow of the anti-icing surface was determined,which is the sum of the heat flux of convective heat transfer and the heat flux of the surface heating caused by friction with the surface layer.The heating power density of the superhydrophobic electrothermal skin was calculated.(2)The overall design of superhydrophobic electrothermal skin was proposed.The design and preparation of the electrothermal film were completed based on the key protection area of the airfoil model.Eventually,superhydrophobic film and electrothermal film were glued together.(3)The wetting performance of superhydrophobic electrothermal skin was characterized.The static contact angle and contact angle hysteresis of the skin surface were measured.The results showed that the skin surface was superhydrophobic and low adhesion.Furthermore,in order to analyze and compare the dynamic wettability of two kinds of skin surface,the bump,bounce and other behaviors of the droplets on the skin surface were studied by using a highspeed camera.The results showed that the dynamic behavior of water droplet on the superhydrophobic surface was: spreading,breaking,contraction,bounce and dissecting,which was significantly different from that of ordinary polyimide electrothermal skin.(4)The thermal properties of the superhydrophobic electrothermal anti-icing skin were characterized and analyzed.The electrothermal temperature distribution of the skin was studied by infrared thermal imager,and the design requirements were verified.In addition,according to GJB150 A,the electrothermal response characteristics of the skin were characterized and analyzed in-30 ?,-40 ? and-55 ?.The experiment results showed a good performance of the temperature response characteristics.(5)The anti-icing performance of the skin were studied under different ice wind tunnel conditions,which included the energy consumption of anti-icing,icing temperature threshold,anti-icing delay time and overflow ice.Comparing the traditional polyimide electrothermal skin and the superhydrophobic electrothermal skin,the experimental results showed that the latter can reduce the energy consumption of the anti-icing about 52% ~ 90%.Compared with the related research,the experimental results had exceeded the international advanced level according to the test report of China Aerodynamics Research and Development Center(CARDC).This paper provides a technical basis and experimental basis for the new anti/de-icing area,and it could resolve the anti-icing engineering problem of a UAV.