基于不等距叶片的串并联泵压力脉动

Pressure pulsation characteristics in series-parallel centrifugal pump with unequal blade pitch

为研究叶片不等间距排布对串并联离心泵压力脉动的影响,基于转子自动平衡理论建立5种不等距叶轮模型.对比分析了不同方案下该泵的性能及压力脉动特性,以提高串并联离心泵的运行稳定性.结果表明:并联或串联运行时,在较小的最小角间距θmin时,扬程和效率都有所下降,在最小角间距为56°或58°时,相比于叶片等间距(原始模型)布置时效率有所增大,其中效率的最大值都出现于最小角间距为56°时;不等距方案在435Hz即1.5倍叶频处出现了新的脉动能量幅值,该能量幅值随着最小角间距的增大而逐渐减小,改善了脉动能量的集中分布;通过对蜗壳周向监测点压力脉动及主频脉动能量幅值的对比,在最小角间距为56°时压力脉动幅值分布更均匀稳定,能量分布更加合理.

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 θ min gets small regardless of running in parallel or in series.When θ min is equal to 56° or 58°,the efficiency is higher than that with equal blade pitch,particularly,the best efficiency appears at θ min =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 θ min .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 θ min =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.