Abstract:For usual parallel pump systems with air surge tank for water hammer protection, the transfer matrix of pump system was established between suction and discharge sumps in a pumping station. The equations of transfer matrix with complex variable were solved by the iteration method and then the natural frequencies and their corresponding modes were obtained for free vibration. A hydraulic vibration analysis was conducted for a long pipe water supply project, and 1st-14th self vibration frequencies and their modes were obtained, in which the natural frequencies of 1st and 14th are 0.010 6 Hz and 0.183 3 Hz, respectively. It was showed that because the self vibration frequency is too low hydraulic resonance cannot occur until the water supply system is subject to a disturbance source with an even low oscillating frequency. The attenuation factor of every order is negative, thus the system always is stable and self-excited vibration will never happen. After the eighth PVC-M pipe segment of the system was changed to a steel one, the same hydraulic vibration analysis was repeated. Because the water hammer wave speed is increased by the change in mechanical property of pipe wall material, the air volume in the air surge tank, self vibration frequency and amplitudes of pressure and flow rate osci-llation are increased as well. This indicates that the water hammer wave speed has a significant influence on self vibration frequency and its modes of free vibration. Therefore, the factors such as material of pipe wall, air volume in water etc should be paid enough attention in a hydraulic vibration analysis since they can alter water hammer wave speed.
于永海, 王金星, 秦晓峰. 空气罐水锤防护的并联泵系统水力振动分析[J]. 排灌机械工程学报, 2013, 31(11): 958-963.
Yu Yonghai, Wang Jinxing, Qin Xiaofeng. Hydraulic vibration analysis of parallel pump system with air surge tank for water hammer protection. Journal of Drainage and Irrigation Machinery Engin, 2013, 31(11): 958-963.
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