Parametric analysis of the liquid hydrogen and nitrogen bubble point pressure for cryogenic liquid acquisition devices

Abstract

This paper presents the parametric investigation of the factors which govern screen channel liquid acquisition device bubble point pressure in a low pressure propellant tank. The five test parameters that were varied included the screen mesh, liquid cryogen, liquid temperature and pressure, and type of pressurant gas. Bubble point data was collected using three fine mesh 304 stainless steel screens in two different liquids (hydrogen and nitrogen), over a broad range of liquid temperatures and pressures in subcooled and saturated liquid states, using both a noncondensible (helium) and autogenous (hydrogen or nitrogen) gas pressurization scheme. Bubble point pressure scales linearly with surface tension, but does not scale inversely with the fineness of the mesh. Bubble point pressure increases proportional to the degree of subcooling. Higher bubble points are obtained using noncondensible pressurant gases over the condensable vapor. The bubble point model is refined using a temperature dependent pore diameter of the screen to account for screen shrinkage at reduced liquid temperatures and to account for relative differences in performance between the two pressurization schemes. The updated bubble point model can be used to accurately predict performance of LADs operating in future cryogenic propellant engines and cryogenic fuel depots.