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渣漿泵軸向力的產生及其平衡軸向力的產生
1. 軸向力的產生
在單吸離心泵中,由于前后蓋板側面所受壓力不同,產生軸向力F1:在懸臂式泵中,由于吸入壓力作用于軸湍上而產生軸向力F2:由于液體流入葉輪進口及從葉輪出口的速度、方向不同產生的動反力F3:對于立式泵,轉子的重量產生的重力F4,因此泵的軸向力應是上述四種軸向力的總和。
(1)由于前后蓋板側面所受壓力不同產生的軸向力F1
對于單吸葉輪,由于作用在葉輪兩側蓋板的壓力不等。圖2-51表示了單吸葉輪兩側蓋板上的壓力分布情況:左側為前蓋板上的壓力分布,右側為后蓋板上的壓力分布。一般認為在葉輪與泵體間液體,因受葉輪旋轉效應的影響,以n/2速度旋轉。所以在葉輪和泵體間的壓力是按拋物線形狀分布的。由圖2-50可以看出:在密封環半徑rw以上,葉輪兩側的壓力是對稱的,方向相反,相互抵消,沒有軸向力;而在密封環半徑r。以下,作用在左側是葉輪入口壓力p1,作用在右側后蓋板上的仍是出口壓力按拋物線分布的壓力,前后蓋板壓差乘以相應的面積就是作用在葉輪后蓋板上的軸向力F1,方向從后蓋板指向葉輪進口。
作用在軸尚上的軸向力F
對入口壓力較低的泵來說,兩軸端上的壓差較小,可以忽路不計。而對于入口壓力較高的懸臂式單吸泵,必須考慮由作用在軸端上的入口壓力所引起的軸向力F2,如圖2 -53所示。
F2與F方向相反。
(3)動反力F
是由于液體進入葉輪后運動方向由軸向變為徑向,就給予葉輪一個反沖力F3與F1方向相反,由于較小,常忽略不計。
(4)轉子重力FA
對立式泵,整個轉子的重量也是軸向力的一部分,在軸向力計算時需要考慮進去。
2.軸向力的平衡
泵的軸向力有時會很大,尤其是在高揚程泵、多級泵中,軸向力可達數千公斤,泵的轉動部分(轉子)在軸向力推動下發生竄動,造成軸承發熱、損壞或發生轉子與定子的研磨,使泵不能工作。因此,消除泵的軸向力是很重要的,常用的軸向力平衡方法有以下幾種。渣漿泵廠家
The generation of axial force of slurry pump and its balanced axial force
1. Generation of axial force
In the single suction centrifugal pump, the axial force F1 is generated due to the different pressure on the side of the front and rear cover plates; in the cantilever pump, the axial force F2 is generated due to the suction pressure acting on the shaft turbulence; the dynamic reaction F3 is generated due to the different speed and direction of the liquid flowing into the impeller inlet and from the impeller outlet; for the vertical pump, the gravity F4 is generated by the weight of the rotor, so the axial force of the pump shall be the above four The sum of the axial forces.
(1) axial force F1 caused by different pressure on the side of front and rear cover plates
For single suction impeller, the pressure acting on the cover plate on both sides of the impeller is not equal. Figure 2-51 shows the pressure distribution on the cover plates on both sides of the single suction impeller: on the left side is the pressure distribution on the front cover plate, and on the right side is the pressure distribution on the rear cover plate. It is generally believed that the liquid between impeller and pump body rotates at n / 2 speed due to the effect of impeller rotation. Therefore, the pressure between impeller and pump body is distributed in parabola shape. It can be seen from figure 2-50 that the pressure on both sides of the impeller is symmetrical and opposite to each other above the sealing ring radius RW, and there is no axial force; while the pressure on both sides of the sealing ring radius R is opposite to each other. Below, on the left side is the impeller inlet pressure P1, on the right rear cover plate is still the outlet pressure distributed in parabola, the pressure difference between the front and rear cover plate multiplied by the corresponding area is the axial force F1 on the rear cover plate of the impeller, and the direction is from the rear cover plate to the impeller inlet.
Axial force F acting on the shaft
For pumps with low inlet pressure, the pressure difference between the two shaft ends is small, which can be ignored. For cantilever single suction pump with high inlet pressure, the axial force F2 caused by the inlet pressure acting on the shaft end must be considered, as shown in figure 2-53.
F2 is opposite to F.
(3) dynamic reaction force F
Because of the change of the direction of movement from axial to radial after the liquid enters the impeller, a reverse force F3 is given to the impeller, which is opposite to the direction F1. Because it is small, it is often ignored.
(4) rotor gravity fa
For vertical pumps, the weight of the whole rotor is also part of the axial force, which needs to be taken into account in the calculation of the axial force.
2. Balance of axial force
Sometimes the axial force of the pump is very large, especially in the high lift pump and multi-stage pump, the axial force can reach thousands of kilograms, and the rotating part (rotor) of the pump will move under the axial force, resulting in the bearing heating, damage or grinding of the rotor and stator, making the pump unable to work. Therefore, it is very important to eliminate the axial force of the pump. The commonly used methods of axial force balance are as follows. Slurry pump manufacturer
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