發(fā)布時間：2018-05-01 10:05

  本文選題：雙吸離心泵 + 葉片進口邊�。� 參考：《蘭州理工大學》2012年碩士論文

【摘要】：雙吸離心泵具有單機流量大、揚程高、結構簡單等特點，是泵類產品中數量多，用途廣泛的一種產品。國內目前生產的雙吸泵在實際運行時的效率較發(fā)達國家低十個百分點左右，為此，有必要對國產雙吸泵進行研究和技術改造，以改善其水力性能。 本文針對國內某廠生產的ES200-250（ns=185.7）型單級水平中開式雙吸泵，依據一元理論對葉輪的軸面流道進行設計檢查，發(fā)現葉輪軸面流道的過水斷面面積沿流道中線的變化規(guī)律在進口邊附近的變化情況不佳；利用CFD軟件對其內部流場進行數值模擬，，發(fā)現葉輪的進口處存在較強的漩渦，由此推斷導致該雙吸泵效率低的主要原因是葉輪進口處的水力設計不盡合理。以此為基礎，根據葉片進口邊是否位于同一軸面（同一軸面、進口邊外緣前掠、后掠）、葉片進口邊的位置，以及葉輪前蓋板曲率半徑的不同設計出了包括原方案在內的共14種模型方案（Aa~Cd、Da、Db，其中Ba為原方案模型）。依據數值計算結果預測每種方案的性能，研究葉片進口邊是否位于同一軸面、葉片進口邊的位置、葉輪前蓋板曲率半徑對雙吸離心泵性能的影響。通過對這些方案全流場數值模擬結果進行對比分析，獲得以下結論： 1.為了研究葉片進口邊是否位于同一軸面對離心泵性能的影響，設計了三組模型A、B、C，其中模型A的葉片進口邊在同一軸面上，模型B的外緣進口邊后掠10o，模型C的外緣進口邊前掠10o。由數值模擬結果發(fā)現，B、C模型在3組模型中能量性能較為優(yōu)秀，其中B模型的速度分布與壓力分布均優(yōu)于模型C，抗汽蝕能力更強。因此對于中高比轉速的雙吸離心泵來說，葉片進口邊不放在同一軸面上可以提高泵的效率，將外緣進口邊前掠或是后掠均可以獲得更高的效率，而外緣進口邊后掠則具有更好的抗汽蝕性能。 2.為了研究葉片進口邊位置對離心泵性能的影響，對A、 B、 C三組模型的原進口邊位置分別進行三次后移，參考木模圖，相對于原始進口邊位置每次分別后置20o、30o、40o，設計出包括原葉型在內的各四種模型方案（Aa~Cd），其中Ad、Bc、Cd分別為三組模型中能量性能較為優(yōu)秀的模型，模型Bc的綜合性能最好，相對于原方案Ba在最高效率點時的揚程提高了1.53m，水力效率提高了6.10%，且高效點右移。 3.在葉輪徑向和軸向尺寸不變的情況下，為了研究葉片間有效流道的進出口面積比對離心泵性能的影響，取B組葉輪為研究對象，Ba、Bb、Bc、Bd四組葉輪的葉片間有效流道的進出口面積比分別為1.70、1.65、1.55和1.41，均高于1~1.3的推薦值。在這四組葉輪中，Bc葉輪的效率最高，Bd、Bb葉輪次之，Ba葉輪的效率最低。這說明在葉輪葉片間有效流道面積比高于1~1.3的推薦值的條件下，仍可以獲得能量性能較好的葉輪，也說明葉片的進口邊位置對離心泵的性能有一定的影響，葉輪進口邊向進口方向延長并不一定能改善其水力性能。 4.對于固定的葉輪入口直徑、葉輪外徑和葉片進出口角，隨著前蓋板曲率半徑的減小，葉輪的最高效率點增高，高效區(qū)變窄，關死點揚程升高；隨著流量增大，前蓋板曲率半徑的變化對揚程的影響較小。
[Abstract]:The double - suction centrifugal pump has the characteristics of large single - machine flow , high lift , simple structure and the like , and is a product with a large quantity and a wide application in the pump product . The efficiency of the double - suction pump currently produced in China is about ten percent lower than that of the developed countries . Therefore , it is necessary to study and technical transformation of the domestic double - suction pump so as to improve the hydraulic performance .

Aiming at the ES200 - 250 ( ns = 185.7 ) single - stage double - suction pump produced in a domestic factory , the axial flow path of the impeller is designed and checked according to the theory of one element , and it is found that the change law of the cross section area along the center line of the flow channel is not good near the inlet side .
The numerical simulation of the internal flow field is carried out by CFD software . It is found that there is a strong vortex at the inlet of the impeller , and it is concluded that the main reason for the low efficiency of the double suction pump is that the hydraulic design at the inlet of the impeller is not reasonable . A total of 14 model schemes ( Aa ~ Cd , Da , Db , where Ba is the original scheme model ) , including the original scheme , are designed according to whether the inlet edge of the blade is located on the same shaft surface ( the same axial surface , the outer edge of the inlet edge is swept , swept ) , the position of the inlet edge of the blade , and the radius of curvature of the front cover plate of the impeller . According to the numerical results , the performance of each scheme is predicted , and whether the inlet edge of the blade is located on the same axial surface , the position of the inlet edge of the blade and the radius of curvature of the front cover plate of the impeller are influenced by the performance of the double - suction centrifugal pump . Through the comparative analysis of the numerical simulation results of the whole flow field of these schemes , the following conclusions are obtained :

1 . In order to study whether the inlet edge of the blade is located on the same axis facing the performance of the centrifugal pump , three sets of models A , B and C are designed .

2 . In order to study the influence of the position of the inlet side of the blade on the performance of the centrifugal pump , the original inlet edge positions of the three groups A , B and C are respectively shifted three times , and the four model schemes ( Aa to Cd ) including the original leaf type are respectively arranged at each time of 20o , 30o and 40o in the position of the original inlet side , and the comprehensive performance of the model bc is better than that of the original scheme Ba at the highest efficiency point . The hydraulic efficiency is improved by 6.10 % , and the high efficiency point is shifted to the right .

3 . In order to study the effect of the ratio of inlet and outlet area ratio on the performance of centrifugal pump , the ratio of inlet / outlet area ratio of impeller to impeller is 1 . 70 , 1 . 65 , 1 . 55 and 1 . 41 respectively , which is higher than that of 1 - 1.3 .

4 . For fixed impeller inlet diameter , impeller outer diameter and blade inlet / outlet angle , with the decrease of radius of curvature of the front cover plate , the highest efficiency point of the impeller is increased , the effective area is narrowed , and the lift of the dead center is increased ;
As the flow increases , the change of the radius of curvature of the front cover plate has little effect on the lift .

【學位授予單位】：蘭州理工大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH311

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本文編號：1828852