Experimental Study on Non-isothermal Bubble Dynamics in Liquid Oxygen under a Magnetically Compensated Simulated Low Gravity Field

The efficiency of gas–liquid separation for cryogenic propellants critically constrains their stable storage and transport in propulsion systems operating under microgravity conditions. In the absence of sufficient buoyancy, gas–liquid separation becomes increasingly dependent on interfacial phenomena, which are highly sensitive to both thermal and gravitational effects. However, owing to the technical challenges associated with cryogenic fluids and reduced-gravity environments, experimental data obtained under low-temperature microgravity conditions remain extremely limited. As a result, the mechanisms governing gas–liquid interfacial evolution and bubble breakthrough under non-isothermal conditions have not yet been systematically clarified.

To address this issue, liquid oxygen was selected as the working fluid, and a ground-based gas–liquid separation experimental platform with continuously adjustable effective gravity was developed based on the principle of magnetic gravity compensation. This platform enables controlled simulation of micro- and low-gravity environments while maintaining precise thermal boundary conditions. A metallic screen was employed as the gas–liquid separation element used in cryogenic propellant management systems. The bubble dynamics in liquid oxygen and the corresponding gas–liquid separation performance were systematically investigated under a range of effective gravity levels and inlet temperature conditions. High-speed imaging was combined with synchronized measurements of pressure and temperature to capture the dynamic evolution of the gas–liquid interface near the metallic screen. Particular emphasis was placed on elucidating the influence of inlet temperature on bubble morphology and the critical bubble breakthrough pressure. The results demonstrate a pronounced coupled effect of inlet temperature and gravity level on bubble shape and interfacial deformation. From the perspective of separation performance, the critical bubble breakthrough pressure of the metallic screen exhibits a clear decreasing trend with increasing inlet temperature. Under normal gravity, the critical breakthrough pressure is 0.042 MPa at an inlet temperature of 96 K, whereas it decreases to approximately 0.011 MPa when the inlet temperature is increased to 102 K. These findings provide reliable experimental evidence for understanding gas-liquid separation mechanisms of cryogenic propellants under micro- and low-gravity conditions.