A Numerical Simulation Method for Vortex Cavitation of Axial-Flow Pump Tip Clearance Leakage

Abstract

The invention discloses a numerical simulation method for the leakage vortex cavitation of the tip clearance of an axial flow pump. By modeling the three-dimensional geometry of the axial flow pump, dividing the calculation grid and establishing the cavitation flow computational fluid dynamics model, the vortex discrimination based Methods The modified cavitation model was used to numerically calculate the cavitation flow field of the axial flow pump, and the cavitation performance of the axial flow pump and the cavitation flow characteristics of the blade tip clearance vortex were obtained through analysis. This method fully considers the influence of vortex flow on the cavitation phase transition process, improves the reliability of the numerical calculation results of vortex cavitation, and realizes the rapid and high-precision numerical prediction of vortex cavitation in the blade tip clearance leakage of axial flow pumps, which is helpful It lays a good mathematical foundation for the research on the flow mechanism and suppression measures of the leakage vortex cavitation of the blade tip clearance of the axial flow pump, and can also be applied to the numerical value of the blade tip clearance leakage vortex cavitation of other bladed hydraulic machines such as mixed flow pumps and turbines. Simulation studies.

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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