叶轮叶片入口边磨损后，圆周速度增大，等于18.8m (参阅上述例子)，而径向速度减小，等于1.71m/s. 这时参数(e/u)tan(p/2)减到0.0244. 但是速度头u/2g增大，ml/2g-18. 8m.
Influence of impeller side wear on cavitation erosion characteristics of slurry pump
The influence of blade inlet side wear on cavitation characteristics is evaluated, and the parameters of the pump in the above example are used.
Impeller circumference speed before blade wear
Cavitation capacity of pump before blade wear of radial velocity of liquid flow
After the wear of the impeller blades, the circumferential speed increases, equal to 18.8m (see the above example), while the radial velocity decreases, equal to 1.71m/s., when the parameter (e/u) Tan (p/2) is reduced to 0.0244., but the velocity head u/2g increases, ml/2g-18. 8m..
Using figure 3-7-12, the 2g0h/ui -0.24 and sh- (ut/2g) X0.24=4.33 after the wear of 100mm at the inlet edge of the blade is obtained, that is to say, due to the wear of the blade inlet side, the suction height is allowed to decrease approximately 0.5m.
The blade working face wear during operation has no effect on the head change, until the blade outlet edge begins to wear, because the blade outlet edge wear actually causes the blade outlet diameter to decrease. According to the formula of the true diameter of the turning impeller outlet (P. A. Baughnitskaya test formula), the drop value of pump head and flow is calculated.
In order to prevent solid particles from entering the front chamber of the pump, flushing water should be supplied because of the wear and tear of the seals during operation. However, according to e H. Kozhevnikova, in order to completely avoid particles entering the seal, the flushing water volume should be about 10% of the pump flow. In practice, little consideration has been given to such a large amount of water (hence a large additional energy consumption). Flushing water is not usually supplied on small and medium-sized slurry pumps.
Forced reduction of flushing water will lead to wear and clearance of seals increased accordingly. When there are a large number of small sediment particles in the mixture, they will enter the sealing gap. Because of the wear and tear of the sealing table, the clearance increases and the overflow increases. At the same time, when the liquid flow rate is fixed in the impeller, the additional overflow q is minimized. When the head and power are the same (Fig. 3-7-13), each performance point of the pump moves to a small flow area. If the performance of the network system remains unchanged, the flow in the system will decrease. On the solid-liquid pumps with various structures, the possibility of adjusting the seal clearance during operation (moving the corresponding seal on the pump and moving the whole rotor on the small pump) is considered in advance, which makes it possible to keep the pump characteristics virtually constant for a considerable period of time.