Reaction thrust of submerged water jets

Abstract

Reaction thrusts of submerged water jets for different cylindrical nozzles are investigated numerically and experimentally. Simplified models of the pressure distribution on the interior walls of high-pressure chambers, the reaction thrust of water jets and the thrust coefficients are all established on the basis of the general characteristics of the isobaric surface near the inlet of the nozzle, respectively. Simulation studies on the reaction thrust are also conducted through a commercial computational fluid dynamics (CFD) software package called FLUENT. In particular, the effects of the inlet conditions as well as the nozzle dimensions on the reaction thrust of the water jet are addressed. Comparison analyses are also performed on the results of the simplified models, the CFD simulation and the experiments. It is concluded from the results that: (a) the model results and the CFD simulation results are in excellent agreement with the experimental results; (b) the nozzle diameter and the inlet conditions exert a significant influence on the reaction thrust of the water jet; and (c) the reaction thrust coefficient is almost a constant, ranging from 1.1 to 1.3. The related conclusions are extended to the study of the water hydraulic flapper-nozzle a servo valve.