Numerical simulation method for axial flow pump blade tip gap leakage vortex cavitation

Abstract

The invention discloses a numerical simulation method for axial flow pump blade tip gap leakage vortex cavitation. An axial flow pump cavitation flow field is subjected to numerical calculation by performing three-dimensional geometric modeling on the axial flow pump, dividing calculation grids and establishing a cavitation flow calculation fluid dynamics model and adopting a cavitation model corrected based on a vortex discrimination method, and the cavitation performance of the axial flow pump and the blade top gap leakage vortex cavitation flow characteristic are obtained through analysis.According to the method, the influence of vortex flow on the cavitation phase change process is fully considered, the reliability of a vortex cavitation numerical calculation result is improved, rapidand high-precision numerical prediction of axial flow pump blade tip gap leakage vortex cavitation is realized, and a good mathematical basis is laid for research on a flowing mechanism and an inhibition measure of axial flow pump blade top gap leakage vortex cavitation. meanwhile, the method can also be popularized and applied to numerical simulation research on blade top gap leakage vortex cavitation of other blade type hydraulic machines such as a mixed flow pump and a water turbine.

Description

technical field [0001] The invention belongs to the technical field of hydraulic mechanical cavitation numerical simulation, and in particular relates to a numerical simulation method for leakage vortex cavitation in the blade top clearance of an axial flow pump. Background technique [0002] Axial flow pumps play a pivotal role in many fields such as industrial and agricultural production, cross-basin water transfer, urban flood control and drainage, and ship water jet propulsion. There is a certain gap between the impeller and the shell, the important working part of the axial flow pump. Although the size of the gap is small, under the action of the pressure difference between the pressure surface and the suction surface of the blade, the fluid will pass through the gap at a high speed and mix with the main flow. The mixed entrainment forms the tip leakage vortex. The leakage vortex in the blade tip clearance can easily induce vortex cavitation, which will not only deteri...

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Problems solved by technology

Since the cavitation model based on the transport equation is derived from the theory of cavitation dynamics and two-phase flow theory, it can describe the thermodynamic non-equilibrium effect of two-phase fluid and simulate the evaporation of liquid and the condensation process of water vapor; however, The establishment of this type of model failed to consider the influence of the vortex in the cavitation flow of the tip clearance leakage vortex on the cavitation phase change process, and underestimated the effect of the vortex rotation angular momentum on prolonging the cavitation life of the tip clearance leakage vortex, resulting in axial flow The prediction accuracy of pump cavitation performance is poor, and the predicted vortex cavitation flow state is quite different from the experimental observation results, and there is a shortcoming of being too short and too small

Therefore, there is still a lack of numerical simulation methods that can effectively reflect the cavitation flow characteristics of the tip clearance leakage vortex.

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