Qualitative Evaluation of a Liquid‐Vapor Separator Concept in Micro‐Gravity Conditions

An innovative liquid‐vapor separator design has been incorporated into a spray cooling experiment, which was flown recently on the NASA C‐9 reduced gravity aircraft. This design is the latest in a series of designs that have been flown in microgravity and elevated gravity in relation to an experimental investigation into spray cooling performance with regard to possible application to high‐performance aircraft undergoing combat maneuvers. Initially, significant problems occurred during flight testing due to the inability of the reservoir to separate the liquid coolant from the vapor under microgravity conditions, which resulted in a loss of coolant to the simulated electronic device that was being spray cooled. Improvements in the design of the liquid‐vapor separator are described in this paper, and experimental data showing the performance of several generations of liquid‐vapor separators are presented. The final separator design went through more rigorous evaluation to compare performance at multiple fill levels, each with a higher percentage of vapor space within the reservoir. It was found that, using the final reservoir design, stable flow operation was achieved in micro‐gravity for mass flowrates of $m = 14,$ 17.5, and 21 [g/s].