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Japan Aerospace Exploration Agency

Stabilizing cryogenic fuel systems

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December 22, 2014

Behavior of two-phase flow with liquid rocket propellant in space observed with sounding rocket

Sounding rocket S-310-43 lifted off from JAXA's Uchinoura Space Center at 23:00 on August 4, 2014. The sounding rocket test used the low-gravity environment created when putting the rocket into ballistic flight*1 for the purpose of investigating such behavior as boiling and flow of cryogenic liquid rocket propellant (liquid nitrogen used for this test) in an environment simulating coasting flight*2 in space. For this experiment, JAXA’s Institute of Aeronautical Technology was in charge of developing cryogenic test equipment to be loaded onto a sounding rocket. This test equipment included a two-phase flow sensor (a cryogenic void meter)*3 that JAXA developed with Waseda University and Tohoku University.

This sensor is a new design to achieve flow rate measurement in a two-phase state,*4 generally considered a challenging task. It contributed to improving launch capabilities in JAXA's H-IIA upgrade project. In this sounding rocket experiment, JAXA performed the firstever cryogenic void measurement in space and later confirmed from analysis that it had obtained enough cryogenic two-phase flow data to examine the precision of a chill-down analysis tool for Japan’s new flagship launch vehicle. JAXA and its partners hope to apply this void meter to the new flagship launch vehicle's onboard flight sensors and ground infrastructure sensors.

*1: A falling motion along a trajectory that traces a parabola as a bullet does.
*2: Flight in a state of no acceleration. Satellites fly around the Earth via coasting flight.
*3: A sensor that detects the proportion of gas and liquid (void ratio) within a pipe.
*4: A state in which different states of matter (gas and liquid, etc.) mix and flow together.

Cryogenic temperature test equipment loaded onto the sounding rocket

Overview of the cryogenic void meter

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