用于空间绿色发动机蓄换热的泡沫镍材料的性能研究

针对空间绿色单组元发动机热启动工况,搭建了蓄换热实验装置,研究了泡沫镍的厚度、孔密度、体密度等参数对其与流动介质瞬时换热能力的影响。研究表明,泡沫镍的瞬时换热能力随厚度的增加而增强;在孔密度较小时(20~70PPI),比表面积是影响泡沫镍的瞬时换热能力的关键因素,瞬时换热能力随孔密度和体密度的增加而增强;在孔密度较高时(100PPI),流阻成为影响泡沫镍的瞬时换热能力的主要因素,泡沫镍的瞬时换热能力大幅增强,但随体密度的增加变化不明显。搭建了强制对流条件下泡沫材料流阻实验装置,测量和比较了泡沫镍与催化剂的流阻,发现泡沫镍的流阻随孔密度和体密度的增加而增大,所有泡沫镍的流阻均小于催化剂的流阻。从实际应用角度看,应综合考虑蓄换热实验、点火实验结果和对泡沫金属的力学性能要求等多项因素来选择泡沫金属的参数。

Study on the Performance of Nickel Foam Serving as Thermal Storage & Exchange Material for Space Green Thruster

Based on the heating start-up conditions of the space green thruster a self-developed apparatus for thermal storage & exchange was set up.The influence of thickness, pore density and bulk density on the transient heat-exchange capacity (THC) between nickel foams and fluids was studied.The results indicated that THC of nickel foams increased with its thickness.The specific surface area was the key parameter to influence the THC under low pore density (20-70 PPI), as THC increased with the pore and bulk density.The flow resistance became the significant parameter under high pore density (100 PPI), as THC increase rapidly while it changes little with increase of bulk density.Moreover, a flow resistance apparatus was built up to measure and compare the flow resistance of nickel foams and catalyzer under forced convection.The results indicated that flow resistance increased with the pore and bulk densities.The flow resistance of catalyzer was higher than that of all nickel foams used in this work.Thermal storage & exchange test, igniting test and mechanical property should be taken into overall consideration to determine the appropriate pore and bulk density of the foam in the view of practical application.