水射流强化疏浚用气力泵提升性能的试验研究

Experimental Research on Enhancing the Dredging Performance of Airlift Pump Aided by Water Jet

为有效消除底泥对水库的淤积影响,避免底泥对水体的二次污染,创新一种螺旋气力泵新型结构,提出脉冲水射流与气力泵一体化清淤新思路,以提高清淤气力泵提升性能。研究不同喷嘴数量、分布方式对气力泵疏浚特性的影响,并将研制的样机用于工程实践。结果表明:水射流喷嘴的引入对气力泵系统扬水量J_(L)影响较小,却可极大的提高扬固量JS;喷嘴可起到解除底部压持效应之功效,使得底部流场脉动,固体表观流速得到大幅提升,使得颗粒易于启动;喷嘴需采用非均匀分布方式,但不能过分“偏心”,不然易引起动压持效应,致使气力提升性能降低;浸入率γ对气力泵疏浚性能影响较大,随着浸入率γ的增大,扬水量J_(L)和扬固量JS均有较大提升,尤其是扬固量峰值相比无喷嘴工况提高了10倍之多。实验室和工程现场试验均验证了气力泵浸入率越大,疏浚效率越高,特别适用于深水疏浚的结论,与理论一致。

To effectively eliminate the deposition effect of sediment on the reservoir and avoid its secondary pollution to the water body,this paper proposes a new philosophy of the integrated dredging of pulsed water jets and air lift pumps to boost the dredging performance of the air lift pump,which can be realized by innovating a new structure of a spiral air lift pump.The influence of the number of nozzles and their ways of distribution on the dredging characteristics of the air lift pump is studied,and the developed model is used in engineering practice.The re⁃sults show that the introduction of the water jet nozzle exerts little effect on the water volume J_(L) of the air lift pumping system but can greatly increase discharge amount of solid JS.The nozzle plays the role of relieving the static pressure on the bottom,so the bottom flow field pul⁃sates,the apparent flow rate of the solid is greatly improved,and the particles are poised to move.However,the nozzle needs to be distribut⁃ed disproportionately but not too“exaggeratedly”,otherwise it will easily trigger dynamic pressure,resulting in reduced lifting performance.Meanwhile,the immersion rateγcan produce a strong influence on the lifting performance.With the increase in immersion rateγ,the amount of J_(L) and JS are greatly improved,and especially the peak of JS is as much as 10 times that under the working condition without noz⁃zle.Based on the laboratory experiments and field tests,it can be verified that the greater the immersion rate of the air lift pump,the higher the dredging efficiency,which is especially suitable for deep-water dredging and is also consistent with the theory.