Research On Pressure Stabilization System Of Water Flow Standard Facility Based On Frequency Converter And Container

There are some factors that affect the flow measurement accuracy, such as field measurement conditions and the performance of the flow meter. In addition, the accuracy also depends largely on the flow standard facility. The flow stability as an important specification of flow standardfacility, will directly affect its accuracy. This paper studies the stabilizer system of the 4~# water Flow Standard Facility at Tianjin University Flow Laboratory and research the factors which affect the stability of the flow standard facility。The major researches are completed as follows in this paper.Firstly, the paper transforms the 4~# water flow standard facility,and increase the container on the basis of frequency conversion. The device has achieved the pressure stabilizer system based on both frequency conversion and container and the serial port communication between the transducer and the computer.Secondly, the paper analyzes two flow stability indexes and researches the reasonability of the two indexes from the perspective of the formula and structure of turbine flow meter。Then the paper chooses one index as the flow stability index from the two.Thirdly, the paper acquires the conclusion that the fluctuation of inverter output voltage can lead to the pump speed fluctuation based on the research on the principle of centrifugal pump speed control. The pump speed fluctuation will directly affect the stability. In testing the stability of the flow, the paper also tests the pressure fluctuation trends of pump outlet. After comparing with the flow fluctuation trends, the paper considers that the flow fluctuations are caused mainly by pump outlet pressure fluctuations. After above work ,the paper further analyzes the pulsation components of pump outlet pressure through the wavelet method, and explains the result.Lastly, This paper analyzes the effects of tank liquid level and container upon the flow stability. For the tank, the paper study the effects from two aspects: the different level of tank and flow disturbance of tank. For the container, the paper explains its effect from two different flow control mode: frequency conversion adjusting speed and flow control with constant pressure.