Research On Refrigeration Mechanism Of Cold Shield System In Spatial Startup

The research and application of spatial cryogenic refrigeration technology is a hot topic in the current development of national defense.The research of stealth technology evolved from this field is also an important part of current spatial technology development.Through the phase change refrigeration of the space refrigerant,the surface temperature of the cold screen can be reduced,the infrared anti-detection capability of the surface can be effectively reduced,and infrared stealth can be achieved.With more and more research on aircraft,the issue of aerodynamic heating in space flight is getting more and more attention.At present,there are many researches on the aerodynamic heat problem of the hypersonic vehicle with airfoil,but there are few reports on the heat transfer law and refrigeration mechanism of the special cold shield system.The research on this aspect seems very necessary.Based on the cold shield system and related theories,this paper analyzes the thermal environment of the cold shield system during the start-up process,and summarizes the basic calculation formulas and methods of the aero-thermal engineering algorithm.Based on the research theories of scholars at home and abroad,using the method of numerical simulation,a three-dimensional model of the external flow field of the cold shield was established.According to the correlation analysis software,the surface heat transfer of the external flow field of the cold shield was simulated under a certain atmospheric environment.Conditions,analysis of the surface temperature,pressure and other changes in the law;then according to the structure of the cold shield,build a simple vacuum experimental platform,according to the principle of heat transfer inside the cold shield,design a schematic diagram of the model,in the surface with different measuring points,It is used to measure the temperature distribution value of the cold shield surface under different control pressures and draw the relevant change curve,so as to obtain the influence law of different control pressures on the surface temperature and pressure.In order to verify the experimental data,this paper uses relevant software simulates and calculates the heat transfer conditions,temperature,pressure and other changes of the cold shield surface under different pressure parameters.Based on the related heat transfer phenomena and related heat transfer theories,the pressure and temperature correlation expressions are obtained and verified in the previous paper.On the basis of the above,comparative analysis and verification are performed;the research on the cooling mechanism of the cold shield system during space start-up Process,of the laws of the factors that may affect were analyzed,and finally determining the aircraft parameters into the cooling conditions of the triple point,and then sum the refrigeration mechanism during the starting.The conclusions are as follows: The cold shield system experiences a very complicated atmospheric environment at the beginning of the flight.This process generates a large amount of aerodynamic heat.Under the effect of aerodynamic heat,a shock wave is generated on the surface of the cold shield,resulting in the head of the cold shield.As the temperature rises,the pressure and density in the head region will rise significantly.At the junction between the middle and bottom of the cold shield,the temperature and density will gradually decrease.Regardless of static rotation or dynamic rotation,the surface temperature of the layered storage system model under vacuum is less than 100 K within 30 minutes;the relationship between the throttle pressure ratio and the cooling capacity is related,and the system pressure is too high after throttling.The greater the cooling capacity obtained,the larger the required cooling capacity of the cold shield in the space.The simulation calculations show that the simulation calculation can achieve the desired goal,and the conclusions obtained and the relevant structural parameters of the cooling system phase change cooling The research of refrigeration mechanism has certain guiding significance and reference value.