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渣漿泵載體參數(shù)對葉片磨損的影響
載體密度和黏度變化對葉輪葉片磨損影響敘述如下。當液體密度增大時,落在入口邊表面上的顆粒數(shù)量減少,即磨損下降。此外,這時顆粒在葉片之問流道內(nèi)的水力粗度(即沉降速度)減少,因此在葉片工作表面上的濃度也減少,這就會導致葉片表面磨損下降。在黏度增加時,在其他條件相同時,雷諾數(shù)下降,迎面阻力系數(shù)增大,因此磨損下降。
上述結(jié)論只對水力磨蝕性磨損有代表性,而不適合于浸蝕和汽蝕所產(chǎn)生的磨損。應該考慮到由于汽蝕和浸蝕使葉輪零件損壞比水力磨蝕性磨損小得多,只在輸送輕磨蝕固液混合物的情況下,可能對泵零件壽命有影響。
根據(jù)泵葉片尺寸和結(jié)構(gòu),對確定的工作狀態(tài)一泵最佳或者接近最佳狀態(tài),即對最佳流量Q或者接近最佳流量進行了葉輪葉片磨損特征和強度的分析。輸送磨蝕性固液混合物泵運行實踐表明,在泵工作狀態(tài)變化時,葉輪特別是葉輪入口段的磨損特征和強度變化
明顯。
在相應加速度場內(nèi),固體顆粒運動特點和沉降速度,與載體介質(zhì)中顆粒移動狀態(tài)即與雷諾數(shù)有關。較大雷諾數(shù)表征顆粒運動的自模狀態(tài)。這時顆粒運動阻力與其運動速度的二次方有關,迎面阻力系數(shù)C是常數(shù)值。較小雷諾數(shù)表征在固體顆粒運動狀態(tài)下運動阻力不是速度的二次方函數(shù),顆粒迎面阻力系數(shù)是變化的。
在自模狀態(tài)下,將有最大的顆粒迎面阻力,也就是說在這種情況下,向心加速度相同時,在葉輪入口運動的顆粒沉降速度小于顆粒運動阻力與其速度小于二次方成正比的非自模狀態(tài)時的沉降速度。在相同加速度場時,較大顆粒以比小顆粒較大的速度運動,較大顆粒的雷諾數(shù)相應地大些。這就表明,大顆粒迎面阻力系數(shù)小于小顆粒阻力系數(shù),即可以認為迎面阻力系數(shù)C間接地表征顆粒的粗度。
B. r.詹德曼假定固體顆粒在葉輪葉片入口的濃度重新分布強度用Co JC/gD參數(shù)表征(式中,Co、D。為液體入口速度和葉輪入口直徑)。
固體顆粒分布不均勻度表征入口邊磨損不均勻性,可以用下列方法加以評價。平均線性磨損等于葉片磨損表面面積與其沿著入口邊的寬度之比。磨損不均勻性可以假定為葉片最大線性磨損量與其平均值之比。如果葉片邊磨損是均勻的,那么葉片磨損表面將出現(xiàn)矩形形狀,平均磨損等于最大值,即它們比值等于1;如果磨損表面為三角形,那么入口邊磨損不均勻性等于2.
詹德曼提出假定,由上述方法確定的磨損不均勾性是參數(shù)? JC1sD.的函數(shù)。這個假定可以概括試驗研究資料。表3 7 3列出葉片邊磨損不均勻性 Kn與參數(shù)比C/ED.之間的關系。
從這些數(shù)據(jù)中可以看出,參數(shù)活JE/gD。的增大,導致葉片入口邊較小的均句磨損。渣漿泵廠家
Effect of Slurry Pump Carrier Parameters on Blade Wear
The influence of carrier density and viscosity on the wear of impeller blades is described below. When the liquid density increases, the number of particles falling on the surface of the entrance decreases, that is, wear decreases. In addition, the hydraulic roughness (i.e. settling velocity) of particles in the runner between the blades decreases, so the concentration on the working surface of the blade decreases, which will lead to the decrease of the wear on the blade surface. When the viscosity increases, the Reynolds number decreases and the resistance coefficient increases under the same other conditions, so the wear decreases.
The above conclusions are representative of hydraulic abrasive wear, but not suitable for erosion and cavitation wear. It should be considered that the damage of impeller parts caused by cavitation and erosion is much less than that caused by hydraulic abrasion. It may affect the service life of pump parts only when conveying light abrasion solid-liquid mixture.
According to the size and structure of pump blades, the wear characteristics and strength of impeller blades are analyzed for the optimal or near optimal state of a pump, i.e. the optimal flow rate Q or near the optimal flow rate. The operation practice of the pump for conveying abrasive solid-liquid mixture shows that the wear characteristics and strength of impeller, especially the inlet section of impeller, change with the working state of the pump.
Obvious.
In the corresponding acceleration field, the movement characteristics and settling speed of solid particles are related to the particle movement state in the carrier medium, i.e. Reynolds number. The larger Reynolds number indicates the self-model state of particle motion. At this time, the particle motion resistance is related to the quadratic of its velocity, and the head-on drag coefficient C is a constant value. The smaller Reynolds number indicates that the moving resistance of solid particles is not a quadratic function of velocity, and the resistance coefficient of particles is variable.
In the self-model state, there will be the maximum particle head-on resistance, that is to say, in this case, when the centripetal acceleration is the same, the particle settlement velocity in the impeller inlet motion is less than that in the non-self-model state where the particle movement resistance is proportional to its velocity less than the quadratic square. At the same acceleration field, the larger particles move at a larger velocity than the smaller particles, and the Reynolds number of the larger particles is correspondingly larger. This shows that the resistance coefficient of large particles is smaller than that of small particles, that is to say, the resistance coefficient C indirectly represents the coarseness of particles.
B. R. Jendman assumed that the redistribution strength of solid particles at the inlet of impeller blades was characterized by Co JC/gD parameters (formulas, Co, D). For liquid inlet velocity and impeller inlet diameter.
The inhomogeneity of solid particle distribution represents the inhomogeneity of wear at the entrance, which can be evaluated by the following methods. The average linear wear is equal to the ratio of the wear surface area of the blade to its width along the inlet edge. The wear inhomogeneity can be assumed to be the ratio of the maximum linear wear of the blade to its average value. If the blade edge wear is uniform, then the wear surface of the blade will appear rectangular shape, the average wear is equal to the maximum value, that is, their ratio is equal to 1; if the wear surface is triangular, the wear inhomogeneity of the inlet edge is equal to 2.
Janderman proposed the assumption that the wear nonuniformity determined by the above method is a function of parameter JC1sD. This assumption can summarize the experimental data. Table 373 shows the relationship between Kn and C/ED.
From these data, we can see that the parameters are live JE/gD. The increase of the blade size leads to the smaller wear of the blade entrance. Slurry Pump Manufacturer