Investigation On The Effect Of Pre-cooling By Water Injection On Inlet Air Temperature Of Aero-Engine

With the emergence of turbine-based ramjet combined cycle engine,there is a huge increase in speed of the aerocraft,realizing the transition from subsonic to hypersonic.However,the temperature of inlet air rising at high altitude and high Mach number is beyond the capacity of existing compressor,affecting the performance of the turbine engine and restricting the use of combined engine.In view of the bad influence of high temperature inlet air,the mass injection pre-cooling technology is proposed.By injecting cooling medium,high temperature of gas is reduced to expand the flight envelope of turbine engine and increase thrust,making greater breakthroughs at flight altitude and Mach number of aircraft.The mass injection pre-cooling technology has the characteristics of fast molding speed and easy installation.Further research on it can support the development of turbine engines at high altitude and high Mach number flight.Therefore,the introduction of the mass injection pre-cooling technology in the high-altitude and high temperature test for aeroengines can explore the cooling effect,investigate the cooling mechanism of pre-cooling technology,and improve the thrust and performance of the engine in hypersonic flight.In this thesis,the high intake temperature of aero-engine is taken as the research problem,and the aerodynamic influence of mass injection pre-cooling technology on the flow field and the cooling effect on high temperature air are mainly studied.Based on high altitude simulation test of turbine engine,the flow channel is established,and the Eulerian-Lagrangian method of multiphase flow is used to simulate the coupling process between gas and water droplet to study the mass and heat transfer process between high temperature gas and water mist,exploring the impact of water injection on temperature of inlet air.Under the condition of high Mach number,the scheme of radial water spraying is studied.At first,the change of flow field is analyzed according to different working conditions.The results show that increasing the amount of water injection has great influence on the cooling effect of inlet air.The pressure loss and the decrease in the uniformity of the outlet flow field are caused by the amount of spray and the Mach number of inlet air,among which the Mach number has a more serious effect on the pressure loss.The mass injection pre-cooling technology has a more excellent cooling performance in high temperature working conditions.Increasing the amount of spray with the increase of working temperature can further improve the heat transfer and cooling effect and reduce the pressure loss.After that,according to the original injection plan,the number of nozzles is increased and the layout is adjusted to make the injection effect more uniform and dense to simulate.Compared with the original plan,the study shows that the dense nozzle layout would improve the temperature drop effect with almost no influence on the pressure drop of the flow field.Finally,based on the calculation of a single fantasy,the influence of the injection temperature on cooling effect of inlet air is explored.According to the results,during the spray at a certain temperature range,temperature drop does not have a good performance with the reduction of droplet temperature.The same is true for the evaporation rate,which fluctuates to a certain extent.Within a certain temperature range,the evaporation rate decreases with the increase of spray temperature.But when the temperature of the spray is low enough,its atomization cooling effect is the best.