Study and'determination of the discharge coefficient on critical nozzles

Abstract

A toroidal Venturi nozzle, operating mainly at critica! conditions and shaped according to the Standard ISO-9300, was selected for the present study. The focus of this paper is to obtain a correlatíon of the díscharge coeffícient on turbulent boundary layer c onditions for gases at Pr=0.7. The study of discharge coefficient is conducted to investigate the effects the viscous stresses at the boundary layer and the curvature of flow field at the nucleus of the nozzle. The determination of this coefficient is based on turbulent boundary !ayer theory and numerical simulation for a two-dimensional flow. The equation obtained was validated experimentally, making a direct comparison between the experimental correlations of the discharge coefficient of ISO-9300 and Korea Research Institute of Standards and Science (K.RISS) in turbulent boundary !ayer. This validation is carried out for throat numbers Reynolds from 1.4 to 2.6\fl06• The coincidence of the theoretical and measurement discharge coefficient by these correlations is better than 0.2%.