科研之友
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摘要
Five kinds of impeller models with unequal blade pitch were established based on automatic balancing theory of rotor-bearing systems to explore the influence of unequal blade pitch on pressure fluctuation in a series-parallel centrifugal pump. Specially, the performance and pressure fluctuation characteristics of the pumps with these impellers were compared and analyzed to improve the operational stability of the pump. The results show that the head and efficiency of the pump decrease as θmin gets small regardless of running in parallel or in series. When θmin is equal to 56° or 58°, the efficiency is higher than that with equal blade pitch, particularly, the best efficiency appears at θmin=56°. An additional fluctuation energy amplitude peak occurs at 435 Hz, i.e., 1.5 times the blade passing frequency in unequal blade pitch cases, and the amplitude decreases gradually with increasing θmin. As a result, the concentrated distribution of pulsating energy has been mitigated. The distribution of pressure fluctuation amplitude is more uniform and stable, and the energy distribution is more reasonable at θmin=56° in terms of comparison of pressure pulsation characteristics and pulsation energy amplitudes in the dominant frequencies at the monitoring points positioned along the circumference of the volute. ?2019, Editorial Department of Journal of Drainage and Irrigation Machinery Engineering. All right reserved.
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