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渣漿泵的特性曲線離心泵中各種損失
一、離心泵中各種損失
1. 機械損失
機械損失功率△Pm主要指葉輪外盤而與液體之間的摩擦而引起的輪盤摩擦損失△Pe、軸與軸承之間的摩擦損失△P1,以及泵軸與密封件之間的摩擦損失△P2等(如圖1- 26所
示),即有:
△Pm=△Pdr+△P1+ △P2
機械損失中輪盤摩擦損失為最大。軸承和密封件間的摩擦損失與軸承和密封的結構型式以及輸送流體的性質有關,但其值相對輪盤摩擦損失要小,為軸功率的1%~5%。
上述機械損失,在液體性質、葉輪和軸承結構、轉速等一定的情況下,幾乎與流量無關,可將它們近似看作常數。
2.泄漏損失
由于泵的轉動部件與靜止部件之間存在間隙,當泵工作時,使間隙兩端的液體因獲得能頭不同而產生壓力差,造成部分液體從高壓側通過間隙向低壓側泄漏,這種損失稱為泄漏損失或流量損失。
泄漏損失主要發(fā)生在葉輪口環(huán)與泵殼間的間隙,多級泵級間導葉隔板與軸套之間隙處,軸向力平衡裝置與泵亮間的間隙,軸封處的間隙等,如圖1- 27所示。
流入葉輪的理論流量Q,不可能全部從泵出口排出,總會有小部分泄漏。如果以q表示泄漏的流量.則泄漏量q與揚程H有關。實踐證明,q=f(H)是一條二次曲線,因一般q值是很小的,故曲線較陡.見圖1-29曲線8。因此,泵排出液體的流量Q與理論流量存在以下關系:渣漿泵廠家
Q=Qt-q
3.流動損失
離心泵內的流動損失包括摩擦阻力損失和沖擊損失等。
Characteristic curve of slurry pump various losses in centrifugal pump
1、 Various losses in centrifugal pump
1. Mechanical loss
Mechanical loss power △ PM mainly refers to the wheel disc friction loss caused by the friction between the impeller outer disc and the liquid △ PE, the friction loss between the shaft and the bearing △ P1, and the friction loss between the pump shaft and the seal △ P2, etc. (as shown in Figure 1-26
, namely:
△Pm=△Pdr+△P1+ △P2
Among the mechanical losses, the friction loss of wheel disc is the largest. The friction loss between the bearing and the seal is related to the structure of the bearing and the seal and the properties of the conveying fluid, but its value is smaller than that of the wheel disc, which is 1% ~ 5% of the shaft power.
The above mechanical losses are almost independent of the flow rate when the liquid property, impeller and bearing structure, speed and so on are fixed, and they can be regarded as constants approximately.
2. Leakage loss
Because there is a gap between the rotating parts and the static parts of the pump, when the pump is working, the liquid at both ends of the gap will produce a pressure difference due to the difference in the energy obtained, resulting in the leakage of some liquid from the high pressure side to the low pressure side through the gap, which is called leakage loss or flow loss.
Leakage loss mainly occurs in the clearance between impeller ring and pump shell, the clearance between guide vane diaphragm and shaft sleeve, the clearance between axial force balancing device and pump light, and the clearance at shaft seal, as shown in Figure 1-27.
The theoretical flow into the impeller Q, can not be discharged from the pump outlet, there will always be a small part of leakage. If q is the leakage flow, then the leakage q is related to the head H. Practice has proved that q = f (H) is a conic curve, because the general Q value is very small, the curve is relatively steep. See Figure 1-29, curve 8. Therefore, the discharge flow Q of the pump has the following relationship with the theoretical flow: slurry pump manufacturer
Q=Qt-q
3. Current loss
The flow loss in centrifugal pump includes friction loss and impact loss.
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