Experiment and Dynamic Mode Decomposition of Cavitating Flow in Venturi

doi:10.3901/JME.2019.18.173

Abstract

Abstract: The previous studies mainly concentrate on the evolution of cavity shape, vortex shedding and pressure fluctuation, etc., while the study of dynamic modes of cavitation flow has not been developed. The flowing structures and dynamic modes of cavitation flow is investigated by means of experiment, numerical simulation and dynamic mode decomposition. The temporal and spatial evolution of cavitation flow in venturi are obtained by experiment, which shows the shedding period is 0.019 5 s. The mass transport cavitation model is used in numerical simulation, results show that the shedding period is 0.02 s, which is consistent with that of 0.019 5 s in the experiment result, and validates the accuracy and reliability of the numerical simulation. The results of unsteady flow field show that the cavity and vortices interact with each other, and cavity shedding is induced by the reentrant jet. The dynamic modes of cavitation flow are obtained by applying dynamic mode decomposition, results show that the frequencies of four dominant modes obtained are times of the shedding frequency. The higher frequency mode has a smaller scale. The mode which represents the time-averaged flow filed reveals the reentrant jet, and the other modes reveal the structure of cavitation development and shedding. Meanwhile, the roll-up process of entertainment fluid induced by the movement of shedding cavity is also revealed. The dynamic mode decomposition can accurately capture the flow mechanism and dominant dynamic behaviors of cavitation flow.

Key words: venturi, cavitation, experiment, numerical simulation, dynamic mode decomposition

CLC Number:

TH312

HAN Yadong, TAN Lei. Experiment and Dynamic Mode Decomposition of Cavitating Flow in Venturi[J]. Journal of Mechanical Engineering, 2019, 55(18): 173-179.

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