Finite-volume-method-based simulation method of cavitation flow in water pipe

Abstract

The invention discloses a finite-volume-method-based simulation method of cavitation flow in a water pipe. The method includes: building a transient flow basic control equation containing free gas; building a grid system containing free gas according to a finite volume method (FVM), and performing control equation discrete; using a Godunov format with space-time second order accuracy to calculate the flux of a control unit interface during pure convection; introducing a source item into the solution to obtain the second order explicit FVM-Godunov format of the discrete equation solution; using two methods to correct pressure according to pressure obtained by calculation, and calculating cavitation volume. The finite-volume-method-based simulation method has the advantages that false numerical oscillation is inhibited by introducing a slope limiter; the influence of the free gas and cavitation on the pressure is considered successfully by introducing the pressure correction coefficient C-ap, unreal pulses near the pressure peak of the cavitation flow are eliminated, and the cavitation in a water pipe system is simulated accurately.

Description

technical field [0001] The invention relates to a method for simulating cavitation flow in a water delivery pipeline based on a finite volume method, and belongs to the technical field of hydraulic numerical simulation calculation of a hydropower station (pumping station). Background technique [0002] When the pressure in the water pipeline system is lower than the vaporization pressure of the liquid, the liquid may vaporize to form cavitation bubbles. These cavitation bubbles may be evenly distributed in the pipeline to form a homogeneous cavitation flow; they may also aggregate and merge into one or more large cavities, resulting in water column separation; even both phenomena exist in the system at the same time. The generation of cavitation bubbles makes the transient response of the system more complicated and more harmful. Many scholars have pointed out that the re-bridging of the separated liquid column may generate short-term high-pressure pulses higher than the Jou...

AI Technical Summary

Problems solved by technology

However, in the classic MOC-DVCM model, when the fine grid is used, the collapse of many holes will lead to unreal pressure pulses in the calculation results

Although the introduction of free gas (MOC-DGCM) suppressed this pulse to a certain extent, the calculation accuracy did not improve much

In addition, due to the limitations of MOC itself, the solution of this type of method is limited to the first-order accuracy

However, the existing methods for obtaining high-order precision solutions, on the one hand, the algorithm is too complex (such as the homogeneous continuous model proposed by Chaiko based on the FVM method), and on the other hand, the calculation takes too long (such as the two-dimensional CFD proposed by Wang Huan et al. method)

The DVCM model proposed by Zhou Ling et al. based on the one-dimensional FVM method, although compared with the MOC-DVCM model, the unreal pulse is obviously suppressed and the second-order accuracy is obtained, but the result still has a certain degree of fluctuation near the highest pressure.

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