Abstract
A two-phase flow ejector is an important part of a water mist fire suppression system, and these devices have become a popular research topic in recent years. This paper proposes a supersonic ejector that aims to improve the efficiency of water mist fire suppression systems. The effects of ejector geometric parameters on the entrainment ratio (ER) were explored. The effects of primary flow pressure (PP) on the mixing process and flow phenomena were studied by a high-speed camera. The experimental results show that the ER first increases and then decreases with increasing PP. ER increases with increasing ejector area ratio (AR). The PP corresponding to the maximum ER of ejectors with a different nozzle exit position (NXP) is 3.6 bar. The ejector with an NXP of +1 and AR of 6 demonstrate the best performance, and the ER of this ejector reaches 36.29. The spray half-cone angle of the ejector increases with increasing ER, reaching a maximum value of 7.07°. The unstable atomization half-cone angle is mainly due to a two-phase flow pulsating phenomenon. The pulsation period is 10 ms. In the present study, a general rule that provides a reference for ejector design and selection was obtained through experiments.