Effect Of Opening Of Flow Control Valve On Pressure Change Characteristics Of Circular Pipe Flow

As an important control element in pipeline flow,the main function of valve is to block or connect the flow of fluid in pipeline.Therefore,the flow direction of fluid in pipeline,as well as the pressure and velocity of fluid can be changed by valve.Fluctuating pressure acting on solid boundary surface is an important parameter in hydraulic design.Fluctuating load,flow-induced vibration,cavitation,scouring and many other engineering problems are closely related to it.Therefore,the study of fluctuating pressure is of great significance for future development.In this paper,the influence of the opening of flow control valve on the pressure change characteristics of pipe flow is studied through experiments.The main research contents are as follows: the whole experimental platform is introduced,including the selection of experimental components,the selection of experimental system,sensors and acquisition system;the experimental signal is analyzed in time domain,correlation analysis and frequency domain analysis,and the influence of flow control valve opening on pressure variation characteristics of straight pipe flow section is obtained;the experimental signal is analyzed in time domain,correlation analysis and frequency domain.The influence of the opening of flow control valve on the pressure variation in the sudden expansion section of circular pipe flow is obtained.Through time domain analysis,correlation analysis and frequency domain analysis of experimental signals,the influence of flow control valve opening on the pressure variation characteristics of pipe flow was obtained.The results of the experiment are as follows: for the clear water flow in straight pipe section,in the time domain analysis,through the waveform diagram under different flow velocities,it is intuitively found that the pressure changes irregularly with time;in the statistical analysis,the data obtained from the experiment obey the normal distribution;with the decrease of flow velocity,the mean square deviation of pressure fluctuation increases first and then decreases;in the correlation analysis,under different flow velocities,the mean square deviation of pressure fluctuation increases first and then decreases.The signal auto-correlation graph is basically a straight line.In frequency domain analysis,different flow velocities have maximum amplitude and maximum power at the frequency of 50 Hz.For the clear water flow in sudden expansion section,in the timedomain analysis,through the waveform diagram of different working conditions,it is intuitively found that the pressure changes with time irregularly;in the statistical analysis,the data obtained from this experiment obey the normal distribution;the velocity at different locations of the sudden expansion is positively correlated with the mean value,and is positively correlated with the mean square deviation value,and the distance between the measuring points is sudden at different flow velocities.The spread distance is positively correlated with the mean and negatively correlated with the mean square deviation.In the correlation analysis,the signal auto-correlation figure under different working conditions is basically a straight line.In the frequency domain analysis,there are maximum amplitudes and maximum power under different working conditions at the frequency of 50 Hz.