Abstract:To investigate pressure-flow characteristics of an orifice meter under unsteady or oscillating flow conditions, the size variation of vortices up- and downstream an orifice plate was theoretically analysed when the flow rate was changing. This variation is the main reason for the instantaneous difference in flow rate between the inlet and the outlet of the orifice. An orifice meter model was built, and the pressure-flow characteristics were analysed based on computational fluid dynamic(CFD)method when the inlet flow velocity was imposed by a sine function at a certain frequency. Results indicated that when the inlet flow was in an oscillating state of low frequency, the pressure drop across the orifice was also in an oscillating state with the same frequency but a different phase. The amplitude of pressure drop increased linearly with increasing amplitude of the inlet velocity, and the linear growth coefficient was correlated with the oscillation frequency. There was a transient difference in flow rate between the inlet and the outlet. The greater the oscillation frequency, or the lower the inlet velocity, the smaller the fluctuation of the transient flow rate. Since a phase delay and an instantaneous flow rate difference exists, there is a deviation between the measured flow rate and the actual flow at the outlet, and the higher the oscillation frequency, the larger the deviation.
朱桂华,洪小波*,徐洪威. 振荡流态下孔板流量计的瞬时压力-流量特性分析[J]. 排灌机械工程学报, 2019, 37(3): 237-241.
ZHU Guihua,HONG Xiaobo*,XU Hongwei. Analysis of transient pressure-flow characteristics of an orifice meter in oscillating state. Journal of Drainage and Irrigation Machinery Engin, 2019, 37(3): 237-241.
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