Research on cryogenic character of spatial low infrared radiated cold-shield with liquid nitrogen

Using the cryogenic cold shield method can decrease the exterior infrared intensity of spacecraft. A model of layered reservoir and gas-liquid separated spatial cold-shield is established. Numerical simulation parameters of flow field are used to calculate the empirical heat convectional relations and obtain convectional coefficients on different boundary conditions, and by substituting different boundary conditions to steady-state heat-transfer simulation process, the regularity of temperature distribution in gas area and liquid area is obtained. A unit heat transfer test model is established, and equivalent radiation method is used to analyze the consistency of the test model in ground and in space. The results show that the maximum temperature reaches 92.9 K from heat-transfer simulation, 107 K from flow-field simulation, and 180 K from experiment in extreme condition when the height of layered reservoir is less than 100 mm. The experimental temperature gradients are similar to the simulated results in shape but larger than simulated results due to the influence of equivalent radiation. The equivalent radiation is close to 1592.6 W/m2, liquid nitrogen maintains 15min on the ground and more than 30 min in space. The layered reservoir model can make the surface temperature of aircraft lower than 100 K and the infrared radiation lower than 0.5 W/m2 in specific time period in space. ©2010 Journal of Mechanical Engineering.