Underwater jet-diffuser ejector propulsion. Real fluid effects

The flow properties and performance of a jet-diffuser and a conventional ejector in an underwater environment, including the influence of losses due to inlet blockage, skin friction, incomplete mixing, diffuser separation and nozzle efficiency have been determined. Analytical methods for the evaluation of the loss coefficients from experiments are described. The importance of a proper selection of pump characteristics to optimize the performance of ejectors of any given geometric size are discussed and some examples of the optimization procedure are presented. The influence of performance limitations due to cavitation, viscous dissipation and self-propulsion are discussed with some specific examples which illustrate these limitations as applied to the performance of ejectors with realistic losses.