调速对低比转数离心泵外特性和内流场的影响

Effects of Rotating Speeds on Performances and Flow Characteristics for a Low-Specific-Speed Pump

调节转速可以改变泵性能,满足一定的性能需求。本文以带分流叶片的低比转数离心泵为研究对象,研究转速对其外特性和内流场的影响。结果表明:转速增加到1717 r·min^-1时,流量6 m^3/h下的扬程提高到11.5 m,达到使用要求。调速后的性能基本满足泵相似定律,但增速提高了最高效率值。调速基本不影响叶轮内相对速度,但改变动扬程和势扬程。对于同一流量,增速所提高的动压在蜗壳中转化为静压。增速使得压力脉动的主要频率从4倍轴频增加到8倍。

Adjusting rotating speed can change pump performance,meeting certain performance requirements.Effects of rotating speeds on performances and internal flow characteristics for a low-specific-speed pump with splitter blades are investigated.When the rotating speed is up to 1717 r-min^-1,the head at 6 m^3/h is increased to 11.5 m and meets the head requirement.Experimental performances in dependence on rotating speeds overall fulfill the pump affinity law,but the best efficiency is improved.Changing rotating speed hardly affects the relative velocity in the impeller,but influencing dynamic and potential heads.For a given flow rate,the increase in dynamic pressure,caused by the speed up,is completely converted into static pressure in the volute.Besides,the dominant frequency of pressure fluctuations in the discharge pipe is shifted from 4 times the shaft frequency to 8 times due to the impeller configuration and the boosting in rotating speeds.