Calculation of throat pipe length in CP type jet pump based on numerical simulation

Based on SIMPLE algorithm and RNG k-e turbulence model,numerical simulation was carried out to calculate the inner flow field of the CP type jet pump with throat pipe of different lengths.By comparison and analysis on their performance and inner flow field,it was found that the throat pipe lengths has important effect on the performance,the pressure distribution as well as the inner flow field of the jet pump.Regardless of cavitation,with the length of throat pipe in the range of(2.5~6.0) times of throat diameter,the peak efficiency will also increase and the point of peak efficiency will move to the right to the larger flow rate ratio region.By analysis of the efficiency,the kinetic energy correction coefficient α and the momentum correction coefficient α′ at the throat outlet section together with the pressure distribution,it revealed that in the range of(3.7~4.5) times of throat diameter,the jet pump performs best in the design duty point,which must be the optimal length of throat pipe for the CP jet pump.