Experimental investigation on cryogenic chilldown performance under high-Reynolds number condition and using interior micro-fin structure

Abstract

Future aerospace vehicle requires a fast propellant fueling and a rapid launching. In the present study, a high-pressure chilldown test platform is established, and two different tube structures, including a straight tube and an interior micro-fin tube, are tested under different inlet Reynolds number (Re) conditions. The test results show that for a typical chilldown case through the straight tube, different boiling mechanisms successively dominate the fluid-wall heat transfer, and inverse annular flow film boiling occupies the maximum proportion of wall temperature decrease. Increasing inlet flow rate could accelerate the chilldown rate, and the time cost in Re=45,000 case is only about 15% of that in Re=5,000 case. For the proposed interior micro-fin tube, the test results verify its excellent performance in improving chilldown rate. Under Re=5,000 condition, the time cost for micro-fin tube case is only about 70 s, which is far less than the time cost by a straight tube case. This astonishing performance is mainly because the micro-fin structure induces a radial velocity component in the inverse annular vapor film. The radial velocity strike acts on the liquid-vapor interface, yielding an interface fluctuation or even a liquid column breakup. Therefore, the liquid phase could contact the tube warm wall earlier, and then a sustained high heat flux gives rise to significant temperature decrease effect throughout the whole chilldown process.