Effect Of Local Pipe Bends On Airlift Pump Performance And Study Of Flow Patternern

Effect of local pipe bends on airlift pump performance and flowpattern of airlift system with three types of rise pipe are investigatedtheoretically and experimentally. The dimensionless expression, whichrepresents the performance of airlift, and critical velocity are derived inthis paper. Moreover, the basic flow patterns of two phase flow andtransition conditions of them are illustrated thoroughly. Pressure powerspectrum and mean pressure in riser pipe are proposed to infer flowpattern of riser pipe and obtain flow pattern map, and then a new type offlow pattern map with coordinate of void fraction and air superficialvelocity is obtained based on Hewitt-Riberts map with coordinate ofsuperficial velocity of gas and liquid. The flowing process of fluid in risepipe with different submergence ratio and volumetric flow rate of airbased on Fluent software is simulated, hence the pressure and velocity inpipe are obtained.The results showed that the volumetric flux of water increased atfirst, and then decreased with increasing volumetric flow rate of air, thatis, there is the volumetric flow rate of air that volumetric flux of watercould be maximum. The volumetric flux of water increased withincreasing submergence ratio. When submergence ratio is over0.4,volumetric flux of water increases significantly. In addition, theperformance of airlift pump without S-shaped pipe is the best, the next issuccessively locally S-shaped below air injector and above air injector. Soif the locally bend is inevitable, it is advisable to locate below air injector.Power spectrum is affected by volumetric flow rate of air andsubmergence ratio strikingly. Flow pattern in the region of0.35m—0.9mfrom the bottom of rise pipe is the same. It shows flow pattern map ofvoid fraction is more convenient and adaptable. It is founded that the flowpattern is changed from slug flow to churn flow to annular flow accordingto the flow pattern map of airlift pump without S-shape pipe. What’smore, it is considered that the effect of locally S-shaped pipe on flowpattern is less than the volumetric flow rate of air and submergence ratiothrough analyzing the flow condition of three types of airlift pump. The theoretical and experimental results are shown to be in good agreement.In a word, this paper provides a new theory method of researching flowpattern. It can provide practical reference for the further study on the flowpattern and performance of airlift pump. What’s more, the experimentalresults have important practical significance for the using of airlift system.