Experimental research on supercavitation in jet pump cavitation reactors for zero flow-ratio conditions

Abstract

We report an experimental study of cavitating flow in a jet pump cavitation reactor (JPCR) with a special emphasis on the supercavitation stage with a tubular supercavitation cavity. This study focuses on the evolution and characteristics of the cavitation for the zero flow-ratio conditions and the supercavitation mechanism. The results show that increasing the limiting flow ratio qr leads to shearing cavitation, which transforms into supercavitation when qr = 1. A cloud cavity forms at the end of the tubular supercavitation cavity and then sheds and collapses downstream. In addition, a wall-attached reentrant jet appears upstream. The results show that the diffuser diffusion angle β, the throat-length–diameter ratio Lth/Dth, and the throat-nozzle area ratio m all significantly affect the stability of the supercavitation cavity, with m and Lth/Dth significantly impacting the characteristic length L/Dth. The supercavitation cavity is induced by the high-speed jet entrainment and the shear layer between the jet and the surrounding water. It is then maintained by the momentum balance in the JPCR. The pressure pulsations are small in the supercavitation cavity and become significantly stronger where the cloud cavity collapses because the high-speed jet retains more energy.

Investigation on the cavitation characteristic of a novel cylindrical rotational hydrodynamic cavitation reactor

“…Hydrodynamic cavitation is a transient phase transition phenomenon [2] , [3] , [4] . At the beginning, scholars' research on hydrodynamic cavitation mainly focused on how to reduce the negative effects of cavitation on centrifugal pumps, ship propellers, and other mechanical equipment such as erosion, vibration, and noise [5] , [6] , [7] , [8] . However, with the deepening of study, researchers have found that the huge energy generated by the collapse of cavitation bubbles can break the chemical bonds of water molecules and produce hydroxyl radicals (•OH) with strong oxidation, which has been effectively applied in the fields of biodiesel preparation, organic degradation of wastewaters, chitosan nanoparticle synthesis, and so on [9] , [10] , [11] , [12] , [13] .…”