渣浆泵流量系数对计算速度的影响
    下面研究系数a对只有隔舌断面高度hg变化时，即泵流量和扬程恒定情况下面积Fs变化时压水室断面上速度的影响。这种分析在抽送细固体颗粒固液混合物泵压水室设计时具有重要意义。在这种情况下，hg 尺寸的选择，不是根据固体颗粒粒径，而是根据压水室内的水力损失和决定其磨损的速度值。
    压水室计算断面上 A值，因而面积F...随着系数。值的增大面增大。因为相对比值A/a为恒定值，其参数A与a成正比增大，计算断面上的流量与a也成正比增大。为了简化分析，采用压水室为矩形，于是得到

从这些表达式中看出，参数A与相对比值R3/R2的对数值成正比增大，而计算断面面积与(R3/R2-1)值成正比增加，即随着相对流量系数。增大，计算断面上的液流速度减小，而且在环形压水室内其平均值最小。

压力短管喉部断面面积也随着a的增大而增大，因而速度u减小。在环形压水室时，压力短管喉部液体流速将有最小值。在其他条件相同时，在环形压水室内特征速度u最小。

知道泵的参数和主要尺寸，就可确定在下列情况下其隔舌断面高度h不同的压水室计算断面上的系数a和速度u：
  (1)扩散管喉品固积F与计算断面面积F,.之比，在各种a值情况下是恒定的(在个别情况下，为简化分析，可以采用F-F..).。

(2) 尽管水力效率有一定变化，当R,=常数时，水泵扬程H=常数。
(3)在估算普通螺旋形压水室内流速时，水力效率可以采用清水泵统计资料(在n,相似情况下)。
如来不考虑压水室断面尺才变化时泵的水力效率(m) 变化，那么根据表达式(3-3 -5)可以写为

式中K,一当泵的参数恒定时为常数， 根据式(3-3-4) 计算，K =0.010DxO/B

根据对不同参数和尺寸泵的对应于最高水力效率状态的关系式U.c= f(a)和ur=f(a)的数值分析结果，得到所研究参数的相似变化(图3-3-5)。 值a从1增大到1.85，将导致计算断面上液流平均速度和扩散管入口速度下降(后种速度下降特别大)。如果考虑在最高水力效率状态时工作，速度Uy和Ur相等，那么对Ug=f(a)来说关系式Ur=f(a)是正确的。这样，在螺旋形压水室过渡到环形压水室时，在压水室各断面上速度都将下降。
众所周知，泵在最佳和大流量状态工作时，在计算断面区最大半径R3 (图3-3-1上点A)上，观察到渣浆泵压水室内磨损穿透。在大多数情况下，决定整个压水室寿命的这种磨损，与计算断面上平均速度大小无关，而与半径R,断面壁面上速度大小有关。因此，感兴趣的是相对流量系数(即压水室形状)对泵参数恒定时速度u的影响的分析。
 为了简化起见，在个别情况下，采用E-F... 于是根据式(3-3-5),扩散管喉部速度为

在简比分析所采用矩形压水室斯面壁面上的液流速度，根据在对应最高水力效率状态下工作时这个断面上的速度矩为常数，则为

在推导速度u3的表达式时，采用了R3=R2+h..=RreM

从图3-3-5上可知，在压水室计算断面外壁上速度也随着相对流量系数a的增大而减小。
    如果采用在各种个断面上速度相等时，其磨损将近似相同，那么扩散管喉部断面和计算断面耐磨性相等的 。条件是速度Ur和..相等，可以写成下列形式
    上述分析指出，甚至在不要求增大隔舌断面高度的情况下，根据大固体颗粒通过的可能性，为了降低压水室断面上的速度，放弃螺旋式压水室是合理的，同时如下指出那样，水力损失增加，即降低整台泵的水力效率。应该注意，因为磨损与液体速度二次方成正比(如下面指出那样)，降低承受最强烈磨损的压水室断面上的速度，是提高渣浆泵体寿命的重要方向之一。渣浆泵厂家

Effect of Flow Coefficient of Slurry Pump on Calculating Speed

Next, the influence of coefficient a on the velocity of the pressure chamber section is studied when only the height of the tongue section changes with hg, that is, the area Fs changes with constant pump flow and head. This analysis is of great significance in the design of pump chamber for pumping fine solid-liquid mixture. In this case, the selection of the size of Hg is not based on the size of solid particles, but on the hydraulic loss in the water chamber and the speed of wear.

The pressure chamber calculates the A value on the section, so the area F... With the coefficient. The increasing face of the value increases. Because the relative ratio A/a is constant, its parameter A increases in direct proportion to a, and the calculated cross-section flow also increases in direct proportion to a. In order to simplify the analysis, the pressure chamber is used as a rectangle, and the result is obtained.

From these expressions, it can be seen that the value of parameter A increases in direct proportion to the relative ratio R3/R2, while the calculated cross-section area increases in direct proportion to the value of (R3/R2-1), that is, with the relative flow coefficient. With the increase of pressure, the velocity of liquid flow on the calculated section decreases, and the average value is the smallest in the annular pressure chamber.

The throat section area of pressure short pipe increases with the increase of a, so the velocity u decreases. In the annular pressure chamber, the liquid velocity in the throat of the pressure short pipe will have the minimum value. When other conditions are the same, the characteristic velocity u is the smallest in the annular pressurized water chamber.

Knowing the parameters and main dimensions of the pump, the coefficient a and velocity U of the calculated section of the pressure chamber with different tongue section height h can be determined under the following conditions:

(1) The ratio of the throat volume F of the diffuser to the calculated cross-section area F is constant under various A-values (in some cases, F-F.) can be used to simplify the analysis).

(2) Despite some changes in hydraulic efficiency, when R, = constant, pump head H = constant.

(3) When estimating the flow velocity in a common spiral pressure chamber, the hydraulic efficiency can be calculated by using the statistical data of clean water pumps (in n, similar cases).

If the hydraulic efficiency (m) of the pump is not considered when the section size of the pressure chamber changes, the expression (3-3-5) can be written as follows.

In formula K, when the pump parameters are constant, it is constant. According to formula (3-3-4), K = 0.010DxO/B.

According to the numerical analysis results of the relations U.c= f(a) and ur=f(a) corresponding to the highest hydraulic efficiency state of pumps with different parameters and sizes, the similar changes of the studied parameters are obtained (Fig. 3-3-5). When the value a increases from 1 to 1.85, the average velocity of liquid flow and the inlet velocity of diffuser will decrease (especially the latter). If the velocity U and Ur are equal when working at the highest hydraulic efficiency state, then the relation Ur = f (a) is correct for Ug = f (a). In this way, when the spiral pressure chamber transits to the annular pressure chamber, the velocity will decrease on all sections of the pressure chamber.

It is well known that wear and tear penetration in the pressure chamber of slurry pump is observed on the maximum radius R3 (point A of Figure 3-3-1) of the calculated section when the pump works in the optimum and large flow state. In most cases, the wear that determines the life of the whole chamber has nothing to do with the average velocity on the calculated section, but with the radius R and the velocity on the wall of the section. Therefore, it is interesting to analyze the influence of the relative flow coefficient (i.e. the shape of the pressure chamber) on the velocity u when the pump parameters are constant.

In order to simplify the process, in some cases, E-F is used. According to formula (3-3-5), the throat velocity of the diffuser is 0.

In the simplified comparison analysis, the velocity of liquid flow on the wall of the rectangular pressure chamber is constant according to the velocity moment on the section working at the corresponding maximum hydraulic efficiency.

In deriving the expression of velocity u3, R3 = R2 + h.. = RreM is used.

From Figure 3-3-5, it can be seen that the velocity decreases with the increase of the relative discharge coefficient a on the outer wall of the calculated section of the pressurized water chamber.

If the velocity is equal on all sections, the wear resistance of the throat section and the calculated section of the diffuser will be approximately the same. The condition is that the velocity Ur and... are equal and can be written in the following form

The above analysis points out that it is reasonable to abandon the spiral chamber in order to reduce the speed of the chamber section, even without increasing the height of the tongue section, according to the possibility of passing large solid particles. At the same time, it is pointed out as follows that the hydraulic loss increases, that is to say, the hydraulic efficiency of the whole pump is reduced. It should be noted that because the wear is proportional to the quadratic of the liquid velocity (as indicated below), reducing the speed on the section of the pressure chamber withstanding the strongest wear is one of the important directions to improve the life of the slurry pump body. Slurry Pump Manufacturer