Study on Turbulent Behavior of Water Jet in Supersonic Steam Injector

Abstract

One of the most interesting devices for Next-generation nuclear reactor systems aimed at simplified system, improvement of safety and credibility is a supersonic steam injector. Supersonic steam injector is a passive jet pump without rotating machine and high efficient heat exchanger because of the direct contact condensation between the supersonic steam and the subcooled water jet. It is considered that flow behavior in the supersonic steam injector is governed by the complicated turbulent flow with large shear stress induced by velocity difference between the steam and water and direct contact condensation. There are various studies about formulation of operating characteristic of the steam injector and jet structure in it [1][5]. According to these investigations, heat and momentum transfer of the steam injector are supposed to be related to the turbulent eddy diffusion. However, the studies about the turbulent flow under the large shear stress with direct contact condensation are not enough. Especially mechanisms of the momentum and the heat transfer are not clarified in detail. Objective of the present study is to investigate the turbulent behaviors of the water jet and the interface between the water and the supersonic steam that play an important role in the heat and the momentum transfer. Radial velocity distribution was measured by a special pitot tube. Fluctuation of the total pressure which doesn’t depnd on the density of the fluid is measured by the pitot measurement. It was found that the streamwise velocity increased as it approaches downstream of the injector. Fluctuation of the total pressure is large at the mixing region of the water and the steam. Visual measurement of the turbulent water jet was conducted by high speed camera in order to identify the position of unstable interface and its behavior. It was confirmed that wave propagated on the interface. And its velocity is obtained.