Abstract
In this chapter, the heat transfer characteristics in the steam injector that has been proposed to introduce into boiling water reactors as a feed water heat exchanger and a safety injection pump are examined. The temperature and the velocity distribution in the injector were measured. The heat transfer rate from the steam flow around the water jet to the water jet was greatly larger than that of the usual turbulent flow in a pipe. High-speed camera pictures revealed the surface of the water jet was very wavy. It was supposed that the wavy motion on the water jet surface created the effective large-internal circulation flow in the water jet, which resulted in the tremendously effective heat transport from the surface into the center portion of the water jet. From the high-speed camera pictures, the characteristics of waves on the surface; the wave height, the wave velocity, and the wave length were obtained. In addition, the dimensionless numbers were found from the parameters that related to the phenomena in the steam injector. By using these dimensionless numbers, a correlation for the heat transfer from steam flow to the water jet in the steam injector was proposed.