Experimental investigation on the discharge and suction gas of multilayer insulation for cryogenic tanks of the Mars lander

Abstract

The foam + multilayer insulation (MLI) is used for thermal protection of cryogenic propellant tanks during the full cycle mission profile of Mars Lander. The unsteady venting and suction gas in the MLI are generated when the rocket ascends, travels and enters Mars, which weakens the insulation performance. An experimental platform was designed to investigate the discharge and suction of interstitial residual gas. The results show that the discharge gas duration of MLI is significantly large. The interstitial pressure values drop below 1 Pa required to be >4.8 h. The venting rate of inorganic fiber paper (IFP) MLI is higher than that of organic fiber paper (OFP) MLI. With the decrease of rarefied gas, the venting rate of OFP MLI is gradually higher than that of IFP MLI. The venting rate of N2 flushing is higher than that of no flushing. The initial venting rate of one-dimensional slit (1DS) is slower than that of perforation. Additionally, the cellular net MLI relaxation time of suction gas is ∼49 s, which is 26.23 % and 64.57 % lower than that of OFP and IFP MLI, respectively. The experimental results provide a reference for the thermal management design of cryogenic propellant.