If a conventional spacecraft propellant management device (PMD) of the screened channel type were employed with a cryogenic liquid, vapor bubbles generated within the channel by heat transfer could “dry out” the channel screens and thereby cause the channels to admit large amounts of vapor from the tank into the liquid outflow. This paper describes a new tapered channel design that passively ‘pumps’ bubbles away from the outlet port and vents them into the tank. A predictive mathematical model of the operating principle is presented and discussed. Scale‐model laboratory tests were conducted and the mathematical model agreed well with the measured rates of bubble transport velocity. Finally, an example of the use of the predictive model for a realistic spacecraft application is presented. The model predicts that bubble clearing rates are acceptable even in tanks up to 2 m in length. © 2004 American Institute of Physics