水泵启动时间对灌溉水力旋流器性能的影响

为解决在水泵启动阶段圆锥型水力旋流器过滤性能较差的问题，利用变频控制技术，以DN50圆锥型灌溉用水力旋流器为研究对象，对含沙质量分数分别为0.451%，0.266%和0.124%的3种水沙混合液分别进行了5，15，30，60和90 s 的5种启动时间，15，30，90和120 s 的4种启动时间以及15，30，60和90 s的 4种启动时间的水沙分离性能试验研究.试验结果表明：水泵启动时间越短，大粒径颗粒的分离效果变差，而启动时间越长，小粒径颗粒的分离效果变差；启动过程中水力旋流器的总分离效率及分级性能随时间均呈现先差后好最后趋于稳定的规律；在相同启动时间的同一时刻下，分级性能随颗粒粒径的增大呈现有规律的波动性变化，0.2 mm以上粒径级沙粒的分离效果最好.结合总分离效率规律，推荐DN50圆锥型水力旋流器在工作流量为15 m3/h时的水泵最佳启动时间为30 s.

Influence of pump start up time on performance of hydrocyclone used in irrigation system

In order to improve the poor separation performance of a conical hydrocyclone during the start up time of a pump unit,taking the DN50 type hydrocyclone as a model,the experimental investigations into the effects of the pump start up time on the separation performance were carried out using the working liquids with three sand mass fractions by means of the frequency variable control technology.The start up times 5,15,30,90 and 120 s for the liquids with 0.451% sand mass fraction,15,30,60 and 90 s for those with 0.266% and 0.124% fractions were applied,respectively.The experimental results showed that the shorter the start up time,the poorer the separation performance for larger size particles; while the longer the start up time,the poorer the performance for smaller size particles.During the start up period,both the total separation efficiency and the classification performance of hydrocyclone are deteriorated initially,and then get better,eventually reach constant levels.At a certain time instance of the same start up time,the classification performance presents a regular wavy variation with increasing size of particles.The particles larger than 0.2 mm in size achieve the best classification performance.It is recommended that the optimal start up time is 30 s when the pump works with the hydrocyclone at the flow rate of 15 m /h.