Hydraulic Characteristics of Liquid Film Generated by Slit Injector

Abstract

Liquid film generated by a jet slit injector on a wall was analyzed experimentally. Liquid film characteristics were investigated by measuring the liquid film thickness distribution for various experimental conditions. At first, the distributions were qualitatively analyzed using backlight imaging. Furthermore, quantitative measurements were performed using a liquid film thickness sensor based on the electric conductance method, which was applied to the high-speed wire-mesh method. The injection angle (15, 30, 45 °), jet velocity (7, 10.5, 13.5 m/s), and injection distance (45, 55, 65 mm) were varied, and the responses of the liquid film were observed. Having increased the injection angle, the main stream thickness decreased and the position of the maximum film thickness moved upstream. A faster jet velocity corresponded to a wider liquid film area and larger perturbation of the liquid film. The injection distance did not affect the characteristics of the liquid film considerably. A hydraulic jump effect was also observed, and a large hydraulic jump affected the film thickness distribution of the main stream. The results of this study can be applied to the development of liquid rocket engines or thrusters using the film-cooling method.