Flow and wave characteristics of jet drainage film under crossflow

Abstract

The interaction between jet drainage films and crossflow is widespread in engineering systems such as liquid rocket engines and nuclear reactor emergency cooling systems. In these processes, an understanding of the flow behavior and fluctuation characteristics of drainage films under crossflow is essential. In this study, an experimental system was constructed to investigate the behavior of jet drainage films under crossflow. The spatial evolution of film offset, average film thickness, base film thickness, wave height, and fluctuation characteristics was investigated under varying crossflow velocities using high-speed imaging and spectral confocal measurement techniques. The results show that the drainage film is shifted to the crossflow direction, and the offset increases linearly with the flow distance, which is inversely proportional to the jet Weber number and directly proportional to the crossflow Weber number. The spatial distribution characteristics of the average liquid film thickness, base film thickness, and wave height are jointly influenced by the jet Weber number and crossflow velocity. The cross-sectional averages of liquid film thickness, base film thickness, and wave height exhibit an initial decrease followed by a subsequent increase with flow distance. The standard deviation of the liquid film thickness was significantly and linearly correlated with its average value, with a slope of approximately 0.3. As the crossflow velocity increases, the liquid film fluctuations on the leeward side of the drainage film are significantly suppressed at low jet Weber numbers, while the liquid film fluctuations on the windward side are notably weakened at the high jet Weber number.