Experimental investigation of the propagation characteristics of an interface wave in a jet pump under cavitation condition

• A dynamic equilibrium interface wave was introduced.
• Interface wave is a pressure propagation front that causes pressure fluctuation and pressure rise.
• The nozzle cavity pressure rises slower compared with the throat cavity.
• The nozzle cavity has lower pressure fluctuation frequency and smaller fluctuation range.
• Increasing cavitation number decreases the bubble region and bubble diameter.

There is a dynamic equilibrium interface wave between the bubble region and the liquid region when a jet pump produces cavitation. The interface wave has an unstable boundary that moves backward and forward, and it is a pressure propagation front that causes the pressure change. The reason why the jet pump upstream pressures remain unchanged is because the interface wave has not arrived there. The interface wave moves upstream with the increase in outlet pressure. The region that it passes through experiences obvious pressure fluctuation and pressure rise. The nozzle cavity pressure rises slower than the throat cavity pressure, and the nozzle cavity has a lower pressure fluctuation frequency and smaller fluctuation range. Therefore, it is a good design for the jet pump to set the suction inlet near the nozzle cavity. In addition, the bubble region length, bubble region volume and bubble diameter decrease as the cavitation number increases in the jet pump. The bubbles completely vanish when the cavitation number reaches 1.53–1.59. Based on the above contributions, it is believed that this study will lay an important foundation for further research on the jet pump cavitation mechanism and cavitation prevention.

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