Study On Simulation Of Airborne Liquid Cooling System And Pipe Design

With the development of the aviation industry, both the number and the power of airborne electric equipments is increasing,and the integration of avionics result in much higher heat flux. Liquid cooling system with virtue of high cooling efficiency is widely used as the air circulating cooling system has been difficult to meet the requirements of avionics system. Meanwhile, as advantages of high specific heat and high storage, airborne fuel becomes an important component of the system heat sink. In addition, the structure of avionics gradually transform from centralized to distributed and the resulting multi branch flow assignment problem become an important problem in the design of liquid cooling system. In this paper, an airborne liquid cooling system and a fuel system are regard as the research object, the main job content and results are described as follows:(1) Simulation model of the components and coolants of the liquid cooling system were built in the MATLAB/Simulink software platform. Physical parameter of coolants was analysised and chose 65# coolan for system and then selected the type and parameters of each component.(2) The fuel system simulation model was built in MATLAB/Simulink and temperature variation in each fuel tank was analysed under the typical aircraft thermal design condition. Influences of flight height, flight speed, solar radiation intensity and liquid cooling system heat load on the fuel temperature of the main tank were calculated. The result shows that the higher flight height, the lower fuel temperature; the higher Mach number, the lower fuel temperature; higher solar radiation intensity or larger system heat load will lead to a higher temperature of system.(3) A numerical simulation based on computational fluid dynamics was carried out for flow limiting loop used in flow distribution. The effect of the diameter and the thickness of flow limiting loop and the coolant flux on the flow resistance of the flow limiting loop were studied. The result shows that the increase of diameter or thickness of flow limiting loop will lead to the decrease of resistance loss. The resistance loss of flow limiting loop increases with the cooling liquid flow.(4) Couple model of liquid cooling system and fuel system were built in MATLAB/Simulink. Flow and heat transfer characteristics of the system under different working conditions were obtained through the dynamic simulation of couple model. Influences of different flight height, flight speed and layout on liquid cooling system were calculated.The result shows that the flow of each branch is carried out according to the thermal load of the electronic equipment in different working conditions. The new layout of system can effectively delay the time of electronic equipment overheating For a given flight condition and operating condition, the temperature of system can be reduced by changing system layout. For a given operating condition, a lower flight altitude or a larger flight Mach number will lead to a higher temperature of system.