Screen Channel Liquid-Acquisition-Device Bubble Point Tests in Liquid Methane

This paper examines the effect of varying the thermodynamic state and type of pressurant gas on the bubble point pressure for screen channel liquid acquisition devices in cryogenic liquid methane across a wide range of pressures and temperatures. Testing of a 325 x 2300 Dutch twill screen sample was conducted at the NASA John H. Glenn Research Center at Lewis Field in Cleveland, Ohio. Test conditions ranged from 106 to 160 K and 0.0618 to 1.78 MPa, using helium, methane, and nitrogen as pressurant gases. The bubble point is shown to be a strong function of temperature and a weak function of liquid subcooling. Pressurizing the propellant above the saturation pressure increase the overall margin in the total allowable pressure drop across a liquid acquisition device when using helium or nitrogen pressurant above the current predicted value. The model predicts well for saturated liquid and autogenous pressurization but underpredicts for a subcooled liquid using a noncondensible gas for pressurization.