Effects of Outlet Geometry of Organ-pipe Nozzle on Cavitation Due to Impingement of the Waterjet

doi:10.3901/JME.2019.18.150

Abstract

Abstract: Although cavitation of the organ-pipe waterjet is induced by its oscillation, it depends on the outlet geometry of organ-pipe nozzle, which has been neglected. Based on the cavitation mechanism of the organ-pipe waterjet, the boundary layer flow characteristics through the nozzle outlet are analyzed, then the relationship between the nozzle outlet geometry and cavitatinggeneration is revealed. The effect of the nozzle outlet geometry on jet cavitation under the same cavitation number is investigated using the noise signal method, and its influence under different cavitation numbers is also explored. The experimental results show that the nozzle outlet parameters including the throat length L₁, flaring length L₂ and flaring angle θ have a significant impact on jet cavitation performance. L₁ influences the jet cavitation directly, L₂ can only influence the cavitation by the jet oscillation, while θ has a dual effect mentioned above. The effects of these parameters on jet cavitation have obvious trends, and there exist reasonable value ranges, within which the jet has a strong cavitation effect. High-frequency oscillation is just the precondition for the self-resonating waterjet to induce cavitation, while to some extent, the nozzle outlet geometry determines the actual cavitation performance of waterjet.

Key words: nozzle, outlet geometry, organ-pipe waterjet, cavitation, cavitation noise

CLC Number:

TG156

CAI Tengfei, PAN Yan, MA Fei, QIU Linbin, XU Pingping. Effects of Outlet Geometry of Organ-pipe Nozzle on Cavitation Due to Impingement of the Waterjet[J]. Journal of Mechanical Engineering, 2019, 55(18): 150-156.

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