Abstract
In order to study the evolution characteristics of suction-side-perpendicular cavitating vortex in an axial-flow pump under low flow conditions, model tests, high-speed imaging, and an SST-CC turbulence model were used to simulate the external characteristics and cavitation morphology of the pump. The evolution law of suction-side-perpendicular cavitating vortex (SSPCV) was revealed by turbulent kinetic energy, liutex vortex identification, and vorticity transport equation. The results show that the evolution of suction-side-perpendicular cavitating vortex at low cavitation number can be divided into three stages: generation, development, and breaking stage. In the generation stage, the turbulent kinetic energy, velocity gradient and vortex kinetic energy continue to increase, reaching the maximum at the early stage of development. Afterwards, due to the viscosity of the water, the vortex slowly dissipates and enters the stage of development. Finally, it is affected by the next blade and enters the breaking stage, which accelerates the dissipation of the vortex. The vortex stretching term and vortex expansion term are the main contributors to the vorticity. During the development of the vortex, the vorticity is mainly caused by the deformation of the fluid micelle. The breaking stage mainly affects the stretching term, and the Coriolis force term cannot be ignored in the rotating coordinates.
Highlights
Published: 25 September 2021Cavitation is a very common phenomenon in hydraulic machinery
Studies on cavitation in axial-flow pumps are mainly focused on the tip reg example, Desheng Zhang et al conducted a large number of studies on the morp development, and evolution of cavitation and leakage vortex in the tip region numerical simulation combined with high-speed photography [15,16,17]
The results show on cavitation in axial-flow pumps are mainly focused on the tip region
Summary
Cavitation is a very common phenomenon in hydraulic machinery. Periodic growth and rupture of cavitation will lead to vibration, noise, and a sudden drop of hydraulic performance [1]. Studies on cavitation in axial-flow pumps are mainly focused on the tip reg example, Desheng Zhang et al conducted a large number of studies on the morp development, and evolution of cavitation and leakage vortex in the tip region numerical simulation combined with high-speed photography [15,16,17]. Explained the development process of SSPCV through research object to study the evolution characteristics of SSPCV, so as to obtain th high-speed photography and numerical simulation. The article verifies and vortex kinetic energy,simulation and the vorticity transport equationand was introduced to c the correctness of the numerical through external characteristics high-speed photography, and analyzes the evolution process the SSPCV, the turbulent energy the contributions of each component to of vorticity.
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