基于环对称掺气的液体射流泵试验研究

为改善液体射流泵性能,提出了在喉管处环对称掺气的方法.通过射流泵水力试验,研究了不同掺气条件下各流量比工况的基本性能及空化特征.试验表明:喉管适量掺气后,未达到极限流量比工况时压力比总体略有提升,效率变化率增值为0.3%~4.9%,接近极限流量比时增效最为明显;极限工况时掺气可以改善空化性能,实测喉管及扩散管的压力脉动明显减弱,且射流泵极限流量比有所增加、正常工作范围变大;较优的掺气率(空气与混合液的体积流量比)约为2%~3%.研究表明:与水相比,空气的黏度系数很小,少量空气被液体携带着贴管壁流动,可降低近壁面水流阻力、减小沿程水头损失,有利于提高射流泵传能效率.在极限工况时空气自然吸入可提升喉管内压力,减免射流泵空化、改善运行性能.环对称掺气的研究成果,可为液体射流泵的性能优化提供参考依据.

Experimental study on liquid jet pump based on cyclic symmetrical aeration

In order to improve the performance of liquid jet pump, a method of cyclic symmetrical aeration in the throat was proposed. Through the hydraulic experiments of jet pump, the basic perfor-mance and cavitation characteristics of different flow ratios under different aeration conditions were studied. The results show that when the throat is aerated properly, the pressure ratio increases slightly when the limit flow ratio is not reached, and the increment of efficiency change rate is 0.3%-4.9% and more obvious when the flow ratio is close to the critical flow ratio. Under extreme working condition, aeration can improve cavitation performance and the measured pressure pulsation of throat and diffuser is obviously weakened.Moreover, the increase of critical flow ratio indicates that the normal working range is enlarged after aeration. The optimum aeration rate(volume flow ratio of air to mixture)is about 2%-3%. The research shows that compared with water, the viscosity coefficient of air is much smaller than water and a small amount of air is carried by the liguid and flows against the inner wall, which can reduce the flow resistance near the wall, and also reduce the frictional head loss. Therefore, the efficiency of jet pump will be improved. Under extreme working conditions, natural gas inhalation can increase the pressure in the throat, reduce cavitation and improve the operation perfor-mance of the jet pump. The research results of cyclic symmetrical aeration can provide a reference basis for the performance optimization of liquid jet pump.