Abstract In order to analyze the effect of valve opening on pulsating characteristics of pressure downstream and improve the stability of pipe flow and transport efficiency, experiments were performed to measure the fluctuating pressure characteristics in downstream flow of the pipe with sudden expansion section at different valve openings. In the experiments, tap water was the working fluid, the valve opening and the length between the valve and the sudden expansion section were varied, and the amplitude of pulsating pressure at different positions along the pipe downstream the sudden expansion section was measured. Furthermore, the influence of different valve openings on the pulsating pressure characteristics of variable cross-section pipe flow was analyzed. It is found that the pulsating pressure curve of the downstream pipe with variable cross section has random but steady characteristics. Using a valve to adjust flow rate can lengthen the pulsating pressure period at each point. The valve can cause an about 50 Hz pulsating pressure downstream the variable cross-section pipe, and the amplitude of the pressure is positively correlated with valve opening. As the distance to the sudden expansion section increases, the standard deviation of fluid pressure first rises and then decreases. As the valve opening increases, the frequency domain of the pulsating pressure energy is widened gradually, and the turbulent intensity of the flow is intensified step by step. Thus, the length of the pressure recovery behind the sudden expansion section becomes longer.
PAN Yue,ZHANG Kai*. Influence of valve small opening on pulsating pressure characteristics of pipe flow downstream sudden expansion section[J]. Journal of Drainage and Irrigation Machinery Engin, 2020, 38(5): 488-493.