自吸离心泵转速与自吸性能关系的研究

为研究自吸离心泵不同转速下的自吸性能，探讨自吸性能与转速的关系，设计了透明自吸离心泵装置，并采用高速摄像机拍摄了自吸初期蜗壳内部的气液两相流流态的演变，记录了吸入管的液位变化。自吸离心泵自吸过程被分为吸入期、进水期和出水期，总结了吸入期和进水期转速对自吸时间的影响规律。试验结果表明，自吸离心泵在较低转速下，自吸时间与转速成反比，因为吸入期结束时气液分离腔内液位未达到最高，含气率是影响自吸性能的主要因素，转速越高，含气率越高，排气效率越高，自吸性能越好；而在较高转速下，部分转速区间内自吸时间与转速成正比，是因为吸入期未结束时气液分离腔内液位已达到最高，影响了排气效率，同时转速越高气体回流速度越快，气体不能及时排出，还出现自吸离心泵自吸未能完成的情况。研究说明了转速与进水管液位和气液分离腔内液位之间的关系，通过解释排气效率揭示了自吸离心泵转速与自吸性能的关系，研究成果可为自吸离心泵的转速设计提供参考。

Study on relationship between speed and self-priming performance of self-priming centrifugal pump

A transparent self-priming centrifugal pump device has been designed and tested to study its performances at different rotational speeds and the relationship between its self-priming performance and rotational speed. We use a high-speed camera to record the development of the gas-liquid two-phase flow patterns in its spiral case at the early self-priming stage, and measure the time variations of the liquid level in its suction pipe. The pump’s self-priming process is divided into the suction stage, the inflow stage, and the outflow stage; the influence of rotational speeds on the self-priming time in the suction and inflow stages is summarized. The experimental results show that at low rotational speeds, the pump’s self-priming time is inversely proportional to the rotational speed, because the liquid level in the gas-liquid separation chamber has not yet reached its highest at the end of suction stage. In this stage, gas content is the dominant factor of the self-priming performance; the higher the rotational speed, the higher the gas content, the higher the exhaust efficiency and the better the self-priming performance. At high rotational speeds, the self-priming time is proportional to the rotational speed only in part of the rotational speed range, because the liquid level in the chamber has reached its highest at the end of suction stage. In this case, a higher rotational speed means a faster gas reflux speed which results in the failure of discharging gas in time and even part of the self-priming function. This study illustrates the relationships of the rotational speed versus the liquid level in the inlet pipe and the liquid level in the gas-liquid separation chamber, and reveals the relationship of the rotational speed versus the self-priming performance of the pump via an explanation of the exhaust efficiency, thereby providing reference towards the design on the rotational speed of self-priming centrifugal pumps.