Abstract
Steam injector is a passive jet pump which operates without rotating power source or machinery and it has high heat transfer performance due to the direct-contact condensation of supersonic steam flow onto subcooled water jet, and it has been considered to be applied to the passive safety system for the Next-generation nuclear power plants. The objective of the present study is to determine the operating ranges of steam injector experimentally. In order to achieve this, flow directional pressure distribution is measured with changing the opening ratio of back pressure valve attached at downstream of SI. It is confirmed that pressure distribution at the diffuser increases as the opening ratio of back pressure valve decreases and maximum discharge exists right before the inoperative point of SI. Furthermore, unsteady shockwave which seems to induce the exponential pressure recovery is observed at the upper part of diffuser and it moves toward upstream with decrease of the opening ratio and triggered discharging of water from the drain as well as the inoperative of SI. It is suggested that the maximum discharge pressure of SI is one of key parameters determining the operating range of SI and is measured with changing the inlet condition such as water flow rate and steam pressure in order to predict operating range experimentally.
