| Double-suction pump has the single stage la ger flow rate, high head, simp lestructure, and other features, is extens ive ly used of pump products. The currentproduction domestic of double-suction pump in the operation effic ie ncy is ten percentlower than the developed countries’ therefore it is necessary to research and maketechno logica l trans formation to domestic double-suction pump, in order to improveits hydraulic performances.Aimed at a single stage double suction pump type ES200-250(ns=185.7) whichproduced in a domestic factory，verify design on impeller by one-dimensional theory, findthat the changing regularity of the discharge section area alone channel midline, especially thearea near the blade inlet edge, is not well; use the CFD analysis software, make a numericalsimulation of the internal flow field, find out that there is a strong vortex near the impellerentrance. By these inferences, the cause of the pump efficiency is the hydraulic design ofimpeller inlet is not so well. Based on this, according to whether the blade inlet edgeposition on the same axia l p la ne (on the sa me axia l p lane, the outer edge o f the b ladeinlet sweepforward, the outer edge of the b lade inlet sweepbackward), the pos ition o fthe blade inlet edge, and the d ifferent radius o f the cover design14differe nt modelscheme, whic h inc lude the prototype (Aa~Cd、 Da、 Db，among these Ba is theprototype). On the basis of the result of the calc ulation, stud y the influe nce ofwhether the blade inlet edge positio n on the same axial pla ne, the position of theblade inlet edge, and the different radius of the cover on performances of thedouble-suction pump. Conclusion follows:1. In order to know the influe nce of whether the blade inlet edge position on thesame axia l pla ne, design three groups of impeller A, B, C. Impeller A’blade inlet edgeposition on the sa me axia l p la ne, Impe ller B’outer edge of the blade inletsweepforward for10o, and impe ller C’outer edge of the b lade inlet sweepbackwardfor10o. The results revea led that, impeller B, C are the better models, for impe ller Bhas the better veloc ity and pressure distributio n, the anti-cavitation performa nce isbetter. So, for the medium and high specific speed pump, sweepforward of the outeredge of the blade inlet can ga in higher effic ie ncy, sweepbackward of the out edge ofthe blade inlet can gain better anti-cavitation performance.2. Backward the inlet edge of the proper type three times respective ly, re fer towooden patterns, backward20o,10o,10o every time respective ly, des ign4modelsof every group inc lude the prototype. Ad、Bc、Cd is the better impeller of every gro up, and the impeller Bc has the best performance. Compared with the prototype Ba, thehead at the best effic ienc y point is1.53m higher, the effic ienc y is6.1%higher, andhigh e ffic ienc y point right moved. This illustrates that, when ja ms appeared at theblade inlet, backward the inlet edge can impro ve the performa nce of the pump, andthere is a best position of blade inlet edge.3. Without changing the impeller radial and axial dimensions, effective area ratiobetween blades of import and export is respectively1.70、1.65、1.55and1.41, higher than therecommended value1~1.3. We can see from this, higher than the recommended value in thecase, not the smaller the ratio, the better the performance of the impeller. The impact of theblade inlet edge shapes to the centrifugal pump performance is very important, extend theinlet side does not necessarily can improve the hydraulic performances.4. For certain impeller entrance diameter, impeller diameter and blade angle, along withthe cover curvature radius reduced, the impeller’s highest efficiency point increase, but highefficient area narrowed, the head curve changes not obviously by the flow increase. Therefore,for certain entrance diameter and impeller diameter, there is a best value of the front covercurvature radius. At the same time, the greater the flow rate, reduce the impeller covercurvature radius to improve the impeller outlet flow state function is more obvious. |
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