Chaotic analysis of pressure fluctuation in bulb tubular pump under different flow conditions
SHI Wei1, CAI Ruimin2, LI Songbai1, SUN Tao1, CHENG Li2*, LUO Can2
1. The Eastern Route of South-to-North Water Diversion Project Jiangsu Water Source Co. Ltd., Nanjing, Jiangsu 210029, China; 2. College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou, Jiangsu 225009, China
Abstract：The vibration source of bulb tubular pump unit is very complex. In order to analyze the vibration law of the unit, the chaotic characteristics of flow field pressure fluctuation were analyzed, and it was pointed out that the vibration characteristics of tubular pump unit originate from the influence of flow field pressure fluctuation. In order to study the chaotic characteristics of pressure fluctuation in the bulb tubular pump under different working conditions, setting up pressure fluctuation monitoring points in impeller, guide vane, bulb wall and flow channel, the chaotic characteristics of pressure fluctuation signals at each monitoring point were analyzed by phase space reconstruction, maximum Lyapunov exponent, phase trajectory, fractal scale and correlation dimension.The results show that the maximum Lyapunov exponent of the pressure fluctuation signal at a specific position in the pump unit is larger than 0, and the signal has chaotic characteristics. Under the three flow conditions, the correlation dimension of the pressure fluctuation signal at the monitoring point at the impeller inlet is between 2.0-2.5, the impeller outlet is between 1.8-2.0, the guide vane outlet is between 1.2-1.5, and generally more than 2.0 in the flow channel. The correlation dimension of different flows conditions is also diffe-rent, the correlation dimension could be used to judge whether the pumps have off design working condition and abnormal hydraulic fluctuation. The conclusions can provide a reference for the prevention and control of abnormal hydraulic vibration of pumping stations.
