The effect of operational and geometrical parameters on the Jet pump efficiency were determined experimentally and numerically. Numerical investigation was held firstly to determine the effect of diffuser angle, mixing chamber length, pump area ratio and driving nozzle position on the efficiency of Jet pump. Commercial computational fluid dynamics (CFD) solver ANSYS FLUENT R 15. 0 using SST-turbulence model was used. The numerical results showed that Jet pump efficiency increases with decreasing both of diffuser angles and mixing chamber length up to a certain value and then pump efficiency decreases. Also, Jet pump efficiency increases with increasing pump area ratio up to a certain value and then pump efficiency decreases. It was found that maximum numerical efficiency is 37. 8 % for pump area ratio of 0. 271. In addition, the numerical results showed that the optimum relative length of mixing chamber is 5. 48 and the optimum value for diffuser angle at which the efficiency is a maximum value is 5º . Experimental tests were conducted to obtain the effects of various operational and geometrical parameters on the performance of the Jet pumps. A test rig was constructed using the optimum design from the numerical results. The CFD’ s results were found to agree well with actual values obtained from the experimental results.

During the operation of a water-Jet pump, cavitation generates noise and vibration, causes surface erosion of the hydraulic components, and reduces the performance of the pump. Suppressing the cavitation is beneficial for improving the stability of the energy system of the water-Jet pump. In order to investigate the mechanism of cavitation suppression and optimize the cavitation performance of the water-Jet pump, the unsteady cavitation flow was studied by numerical simulation and experiment in this paper. Using high-speed photography technology on a closed test platform, the cavitation flow structures in the water-Jet pump were captured, and the physical process of cavitation evolution was revealed. Based on this, in order to obtain the cavitation flow characteristics closely related to the cavitation performance, the cavitation flow in the impeller tip clearance was studied by numerical simulation, the vorticity variation rate in the tip clearance was analyzed, the effects of different cavitation conditions on the vorticity in the tip clearance were revealed. Additionally, this paper analyzed the pressure pulsation characteristics of the tip clearance under different cavitation conditions, and emphatically analyzed the influence of the cavitation flow on the tip clearance pressure pulsation.

In the current research, numerical analysis was used to investigate the flow behavior through the axial Jet-pump with various mixing chamber configurations (straight pipe and straight pipe-diffuser-straight pipe) in the presence of inlet swirling flow and its influence on the pump performance. The effects of introducing inlet swirling flow in the suction chamber and in the motive flow line, are numerically investigated. The optimum swirl angle in the suction chamber is found to be 45o which yields the maximum pump efficiency of 38.08 % for the second configuration of mixing chamber system. Consequently, the inlet swirl generally decreases the desired mixing chamber length. Additionally, the new mixing chamber configuration enhances the mixing process compared with the traditional mixing chamber. On the other hand, imparting a swirl in the motive line inversely affected the pump performance. Engendering a swirl in suction chamber causes an improvement by 12.76 % in the pump efficiency compared to the same pump configuration without swirl. The optimum tail pipe diffuser angle is found to be 3o.

This paper investigates the influence of a weak-Jet on the development of a turbulent axisymmetric strong Jet. A parametric study is carried out to evaluate simultaneously the effect to the Jets-spacing (S/D=3 and S/D=7. 5) and their velocity ratios in range 0≤ λ ≤ 1. The mixing phenomenon is studied numerically by the finite volume method using the 3D-RANS second-order model, which gives a good agreement with the available data. Three distinct regions of this type of Jets interaction are evidenced. This study confirms that the Jets spacing affects strongly the converging region and has a minor effect on the combining region. It is found that the weak Jet attracts the strong Jet and the combining region extends from 30D to 40D where the self-similarity of a single Jet is obtained. The Jet width decreases when velocity ratio and Jets spacing augment. In the combining region, in comparison with the free Jet, it is found that the addition of a weak-Jet increases the decay rate of the centerline velocity.