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采用脉冲示踪法研究离心泵的停留时间分布(RTD),将离心泵与等径等体积空管对比,定性描述了离心泵的返混特征,考察了泵前阀控、泵后阀控、转速控制对RTD的影响.结果表明,RTD曲线呈单峰分布,泵内有死区存在,返混大于等径等体积空管,无因次方差为0.39?0.61;离心泵的返混程度既不靠近平推流,也不靠近全混流,受流量影响显著,随流量增大,返混显著减小.3种流量控制方式对离心泵返混有一定影响,转速控制的返混情况明显大于2种阀控方式,2种阀控方式的影响较接近;随流量减小,流量控制方式引起的RTD差异更显著,3种方式的无因次方差的最大相对偏差达13.6%.
The pulse-tracing method was used to study the residence time distribution (RTD) of the centrifugal pump. The centrifugal pump was compared with the equal-volume air tube. The back-mixing characteristics of the centrifugal pump were qualitatively described. The valve pre- Speed control on the RTD.The results showed that the RTD curve showed a single peak distribution, there was a dead zone in the pump, backmixing is equal to the equal volume of empty tubes, the dimensionless variance was 0.39 ~ 0.61; Not close to the thrust flow, nor near the full flow, affected by the flow significantly, with the flow rate increases, back mixing significantly reduced.3 flow control mode of centrifugal pump backmixing has some impact, speed control backmixed situation was significantly greater than Two kinds of valve control methods and two kinds of valve control methods have the similar effects. With the decrease of flow rate, the difference of RTD caused by flow control method is more significant, and the maximum relative deviation of the three methods is 13.6%.