| Aircraft icing is a serious factor affecting flight safety.As early as the late 1920s,people began to study the phenomenon of aircraft icing,and gradually gave birth to a variety of aircraft anti icing technology.So far,the aerothermal anti deicing technology based on engine has been widely used in transport aircraft.At present,with the rapid development of all electric aircraft,UAV and other new aircraft,the electric anti icing technology of aircraft has entered the key stage of breaking through the tradition and promoting the application.In this study,the phase structure,micro morphology and electric heating properties of carbon nanotube films(CNTF)prepared by chemical vapor deposition(CVD)were characterized.A design scheme of aircraft electric heating anti deicing system using this kind of carbon nanotube film as the main heating material is proposed,and the preparation process of aircraft electric heating anti deicing system sample is explored.The design scheme of aircraft electric heating anti deicing system proposed in this study uses carbon nanotube film and epoxy resin and other lightweight materials,and explores the shape and size of carbon nanotube film,circuit connection mode,structure of electric heating system and preparation process of aircraft electric heating anti deicing system sample.The adhesion of the adhesive layer on the surface of the sample,the surface temperature distribution on the skin side of the sample under different power supply conditions,and the relationship between the temperature and time on the skin side of the sample under different heat flux conditions were characterized.On this basis,through the numerical calculation based on ANSYS software and the actual anti deicing function test of the sample,the application performance of the aircraft electric heating anti deicing system sample is studied.The main results are as follows:1.The optimized design and preparation scheme of aircraft electric heating anti deicing system sample is as follows:after cleaning the surface of aluminum alloy plate with anhydrous ethanol,a 75μm thick epoxy resin wet film is prepared on the surface.After drying the wet film for 1 h,the designed"2"-shaped carbon nanotube film was pasted on the semi cured film,and then the material was dried for 1 h to make the epoxy resin layer completely cured.After the wire and the temperature control switch are pasted and connected,a layer of epoxy resin matrix composite reinforced by glass fiber tape is covered on the surface of the sample as the protective layer,and the protective layer is completely cured after drying for 2 h.The PTC temperature switch controls the circuit on and off when the sample of aircraft electric heating anti deicing system is electrified and heated.When the system temperature reaches the design value,the PTC temperature switch will be disconnected,the system will stop heating and start to cool down.When the system temperature drops to a certain extent,the PTC temperature switch will be connected again,and the system will start heating again.2.The adhesion of epoxy resin layer on the aluminum alloy plate is high,which can prevent the electrothermal anti deicing system from falling off the aircraft fuselage due to working vibration.When the aircraft electric heating anti deicing system sample is electrified and heated,the temperature distribution on one side of the skin surface is relatively uniform under various temperature conditions.In the process of continuous operation,the outer surface temperature of the skin is between 43℃and 55℃,which is conducive to the reliable removal of ice or supercooled water on the surface of the aircraft wing.3.When the heat flux reaches 1193 W/m~2,the surface temperature of the aircraft electric heating anti deicing system can reach the upper limit of 55℃.The results of ANSYS numerical calculation show that when the heat flux reaches 3553 W/m~2,the surface temperature on one side of the skin can reach the upper limit of 55℃.From the ground to the altitude of 10000 meters,the change rate of the input power required by the electric heating system is small.Therefore,it is only necessary to add a 1～2.5 A variable current limiter in the circuit to achieve more stable power regulation.4.According to ANSYS modeling and numerical calculation,the largest part of the thermal stress generated by the aircraft electric heating anti deicing system sample in the process of power on heating is borne by the aluminum alloy,that is,the aircraft bearing structure.The average thermal stress of the largest part is about 100 MPa,and the maximum thermal deformation strain is only 0.438%.Therefore,in practical application,the structure and anti-deicing function are little affected by thermal deformation. |
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