| Flow rate is an important parameter in pump operation,its accuracy measurement is more difficult,and real-time and accurate monitoring of flow rate plays an important role in the safe and economic operation of pump station.At present,there are still many challenges in measuring accuracy and real-time monitoring.This paper mainly aims at small and medium-sized pump stations with poor flow measurement conditions at the inlet,uses numerical simulation to obtain differential pressure and flow data,studies the relationship between the flow at the outlet section and differential pressure,and obtains a suitable fitting curve equation.By comparing the test data,the error accuracy is determined,and the flow is deduced according to the differential pressure.It has perfected the research methods of related aspects and has certain engineering practical value and research significance.The unsteady calculation of the pump device with different placement angles of 0°,4°and-4° was carried out to obtain the flow rate and pressure difference at each measuring point,and the function expression was obtained by fitting the relationship between flow rate and differential pressure.The data of differential pressure,flow rate and pressure pulsation of water elbow measured by field tests were numerically simulated to analyze and establish the relationship between flow rate and differential pressure.And analyze the feasibility and accuracy of the flow measurement method of outlet bend pipe.The specific research results are as follows:To determine the optimal differential pressure measurement section,the impeller,guide vane and outlet flow channel are analyzed.With the increase of the flow rate of the impeller,the pressure gradient of the impeller at each placement Angle is obvious and uniform,the pressure of the blade inlet changes from low to high,the pressure zone at the impeller rim decreases with the increase of the flow rate,and there is no stress concentration area,so the water pump can operate stably and efficiently.The pressure distribution of guide vane at different placement angles is similar,indicating that guide vane body can effectively recover the kinetic energy of water flow,effectively reduce the velocity loop,and has a good diversion effect on water flow.The overall internal flow pattern of the outlet bend is good,the overall streamline is smooth,the energy can be transferred well,and the overall flow pattern is relatively stable.At each placement Angle,the velocity outside the bend is lower than the velocity inside,and the high-pressure area is located outside the bend.So,the flowmeter is placed on the inside and outside of the bend on the horizontal axis.The position of the maximum differential pressure point is located between the outside of the bend at sections 3-3 and 4-4.Through the numerical simulation of the measurement of differential pressure points of each combination and the analysis of the measurement points of high-pressure area and lowpressure area,it is concluded that the best differential pressure combination of each placement Angle is A3 C,and the relationship diagram of flow differential pressure is drawn.The optimal flow differential pressure curve was obtained by physical model verification.The coincidence degree of pressure pulsation between the physical model and the numerical simulation is good,and the law is similar.The pressure pulsation amplitude of inlet,impeller and outlet decreases with the increase of flow rate at each placement Angle,and has obvious periodicity at different flow rates,and the amplitude decreases with the increase of flow rate.The waveform conforms to the variation law of the three-blade axialflow pump.The amplitude at the inlet and outlet fluctuates regularly in a certain range,and the fluctuation range is smaller than that at the impeller.Through the analysis of the timedomain diagram and the frequency-domain diagram,it is found that the pressure pulsation law corresponding to different placement angles is similar. |
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