A slip with entrained liquid fraction approach to compressible two-phase flow in nozzles

Ideal flow theory adequately predicts pressure drops, critical mass flowrat es and critical pressure ratios for single-phase gas flows in nozzles. A mo del based on these principles has been developed for two-phase, gas-liquid flows using a slip with entrained liquid fraction approach. The method reli es on being able to establish the momentum flux of the fluid in the upstrea m supply pipe and therefore allows pipe flow correlations for slip ratios a nd entrained liquid fractions to be used at the nozzle inlet. Choking condi tions are established from an isentropic pressure pulse approach. This prod uces a speed of sound for the two-phase mixture that gives choking conditio ns that are compatible with the end-limits of the momentum and energy equat ions used to estimate the pressure drops for non-choked compressible flows. This allows a consistency in approach between non-choked compressible and choked flows. The model predictions of pressure drops, critical pressure ra tios and critical mass flowrates compare well with data sources and are an improvement on those made by other models available in the open literature.