Experimental study on an impingement high-pressure steam jet

An experimental study on impingement high-pressure steam jet was performed as one of the efforts to establish evaluation methods for effects caused by a jet under the postulated pipe rupture accident in a nuclear power plant. An ejected steam jet from a nozzle into the atmosphere is impinged vertically on the flat plate. Nozzle reaction, jet impingement force and impingement pressure distribution were measured over a wide range of impingement distances. Employed nozzles are circles and ellipses. The steam is supplied under steady state and dry saturated, and the pressure is approximately 4.56 MPa. Form the data of nozzle reaction and impingement force, these are mutually equal and are proportional to the stagnant pressure upstream of the nozzle; and from this data, the thrust coefficient for each nozzle was calculated. Based on the data of impingement pressure distribution, the jet is roughly divided into three regions on the axis according to the characteristics of distribution in both circular and elliptical nozzles. In addition, in the case of a circular nozzle, locations where the characteristics of distribution distinctly change depend on the location of Mach disk. In the case of an elliptical nozzle, expansion on the minor axis is remarkably higher than on the major axis, particularly near the nozzle exit. (orig.)