Numerical Simulation Of Control Valve Cavitation And Noise

Due to the complex structure of the internal flow passages and the throttling characteristics of the valve trim,the control valve generates strong pressure pulsations or vortices during the entire operation of the regulating valve,especially while open or closed.The occurrence of water hammer,cavitation,and flow-induced noise affect the precise control of the control valve and its subsidiary control system,and does great harm to the health of the workers.Focusing on the problems of cavitation and flow-induced noise in the flow path of the regulating valve,the following researches have been conducted on the control valve and its associated control system.(1)Introduced the important role of regulating valve for industrial production and problems during operation.The importance and necessity of studying the cavitation and the noise of the flow-path were proposed by Combining the research status quo and methods of regulating valve cavitation and flow-induced noise at home and abroad.(2)Introduced the typical structure and the working principle of the regulating valve as well as the variable parameters and the specific conditions needed to achieve cavitation and flow-induced noise;Besides,the numerical simulation,basic theoretical knowledge of flow-induced noise,turbulence model,multi-phase flow model,and dynamic mesh model to study the cavitation of the control valve were also introduced.The cavitation model was mainly introduced to lay the groundwork for the subsequent numerical simulation.(3)Established three-dimensional model and the division of grid of regulating valve flow channel and listed the boundary conditions that need to be used in numerical simulation research of control valve cavitation.By using the Software CFD(Computational Fluid Dynamics),simulated operating conditions at different opening degrees and different inlet and outlet pressures of control valves.The flow field characteristics about the flow channels of the regulating valve under different operating conditions were compared and analyzed,as well as the influence of different opening degrees or various pressure differentials of inlet and outlet to the cavitation.The degrees of the cavitation could be simply described by adjusting the gas phase volume fraction and cavitation number in the valve and it provided reference and basis for reducing the cavitation in the control valve by this way.(4)Introduced theoretical knowledge of acoustic theory,the causes and types of noise generated in the regulator valve,briefly described the type of the stream-induced noise sound source.The results of steady-state numerical simulation about the flow field of the control valve was used as the initial value for the transient-state one.The sound source information extracted through transient calculation used as excitation was imported into the acoustic simulation software LMS Virtual.Lab for noise calculation to simulate with different opening degrees.Finally,compared and analyzed the cavitation phenomenon and the flow-induced noise in it.It provided reference and basis for reducing the cavitation phenomenon and flow-induced noise in the regulating valve through the aboved research,besides,the new ideas and methods for the optimal design of the regulating valve are also presented.