渣浆泵转速对叶轮磨损的影响
一、 泵转速对叶轮入口边磨损和出口边磨损的影响
    在相似状态时，液流速度与转速比值成正比，而磨损量与转速三次方比值成正比。于是泵的工作部件其中包括叶轮在输送固液混合物时的单位体积磨损量与转速二次方比值成正比，用FrY160/31.5型试验泵抽送平均粒度为10mm砾石固液混合物试验，在转速从

1000r/mnin变化到1450r/min时，证实了这种关系。

在选择重新设计泵的转速时，在流量Q和扬程H给定的条件下，必须评价泵零件在不同转速时(Q和H不变时）的磨损。这时，最有意义的是承受最严重磨损的叶轮。

因为叶轮叶片入口边和出口边水力磨蚀性磨损过程各不同，所以分别评价转速对它们的影响。
    现在就研究叶片入口边磨损强度。根据式(3-7-2)，入口边磨损量取决于液流相对速度的三次方和液液角和叶片安放角正弦之比值。不同转进时，叶轮人口直花之比等于单位直径之比（在相同入口直径系数ko时），值为

如果叶轮宽度变化与入口直径成正比，那么所得到的关系式是正确的。但是，在设计输送固液混合物泵时，除了流量和扬程之外，过流断面最小允许尺寸也是给定的，即在转速变化时，断面尺寸，其中包括叶轮宽度，都应该保持恒定。因此，在评价转速对磨损影响时，具有实际意义的是下列情况，即此时除Q=const和H= const外，叶轮宽度b是常数。这时，轴面速度之比与D,b积成反比cna2/c1o =(n2/m)/0.
    因此，入口速度三角形不相似。因为圆周速度与转速的2/3次方成反比，所以相对速度之比(unin/un.n)<n/m)0.完全可以确信，在转速降低时，液流角B.增大，即hinl./ing..>1n [根据式(3-7- 4)]，这将导致磨损有所增加。因而，叶片人口线性磨损量之比为转速的函数，即有
只根据对相对速度值的分析，不能评价叶片迎面的磨损量和叶片出口边的磨损量，因

为固体颗粒在叶片迎面上的浓度不是常数，并且不等于平均浓度，磨损不仅与速度有关，前且与颗粒浓度有关。因此，确定叶轮转速对叶片表面磨损的影响，不仅要考虑相对速度而且也要考出固液混合物靠近磨损表面浓度变化。
    为了计算承受最严重磨损叶片出口边区液流相对速度，下面分析转速下降即比转速降低时速度三角形的变化。在这种情况下，叶轮出口处圆周速度u2和径向分速度Cn减小(由于Q= onst时直径D,增大)，但是c.有所增大和叶轮出口液流相对速度w;减小，这将导致磨损降低。
  由于上述速度和磨损的计算结果可以得到，以一定近似程度可以采用
  根据全加速度在圆周切线方向上投影响的分析[式(3- 7 -3)]，可以确定固体颗粒在叶片迎面上浓度与转速之间的关系，而颗粒在叶片之间流道内浓度重新分布强度与切线加速度有关。加速度ar的三个组成部分中的最大值，通常是式(3-7-3) 右边第一项，一般它决定了aT值。在转速降低时，第二项和第三项有所减小，并且第二项是由于叶轮流道长度增加所致，第三项是由于叶轮尺寸其中包括叶片曲率半径Ru增大所致，但是第三项的值远小于前两项之值。
二、固体颗粒浓度的影响
  在进一步分析时，不考虑式(3-7-3) 的第二项和第三项，并且采取固体颗粒在叶片之间流道内的浓度与ar成正比。于是，在不同转速时，颗粒在叶片迎面上的浓度之比等于它们在相应加速度场内沉降速度之比
    根据式(3-7-2) 和式(3-7-5)，考虑到相对速度和固体颗粒浓度的变化，当转速变化时，线性磨损量比值为

确定转速降低时，例如，降低1/3（从n=1500r/min降到n=1000r/min)时，线性磨损量的变化)，即叶片出口处线性磨损量大致降

低1/2左右，

根据对叶片之间流道内发生的现象分析和考虑一些假设，可以得到式（3-7-7）和计算结果。这些现象的复杂性，不允许考虑所有影响叶片在转速空化时磨损的因素，所以，实际上转速降低时，磨损量下降，可能有些别的原因，就是上面所得到的那些原因。例如，根据所进行的分析，采用所有处在固液混合物中的颗粒都很小。如果混合物中含有大的固体颗粒而不影响叶片工作面(或者称为迎面)的磨损，那么由于转速下降而磨损减小将是相当小的。此处，转速下降将导致(根据公式d,-1.26.6N元)临界尺寸d增大，即处在固液混合物中参与叶片工作面磨损的小颗粒部分增加:这时磨损增加，即根据式(3-7-7)得到的磨损下降将小一些。
    没有进行过那种检查叶轮磨损量与转速之间关系的专门试验(在所有其他参数保持相等时)。根据砂泵转速降低运行资料以及全苏非金属建筑材料和水力机械化科学研究所进行的两台挖泥泵转速比额定转速值降低1/3时串联试验结果，叶轮寿命T与转速之间的关系为式中，m=1.8~2。渣浆泵厂家

Effect of Slurry Pump Speed on Impeller Wear

1. The effect of pump speed on impeller wear and outlet side wear.

In the similar state, the liquid flow velocity is proportional to the ratio of rotational speed, while the wear rate is proportional to the ratio of rotational speed cubic. Therefore, the working parts of the pump include the unit volume wear of impeller when conveying solid-liquid mixture, which is proportional to the second square ratio of rotational speed. The average particle size of gravel solid-liquid mixture is pumped by FrY160/31.5 test pump. At rotational speed, the wear rate of impeller is proportional to the second square ratio of rotational speed.

The relationship was confirmed when 1000r/mnin changed to 1450 r/min.

When choosing the speed of the redesigned pump, under the given conditions of flow Q and head H, it is necessary to evaluate the wear of pump parts at different speeds (when Q and H are unchanged). At this time, the most significant is to bear the most severe wear impeller.

Because the hydraulic abrasive wear process at the inlet and outlet sides of impeller blades is different, the effect of rotation speed on them is evaluated respectively.

Now the wear strength of the blade inlet is studied. According to the formula (3-7-2), the wear rate at the inlet depends on the ratio between the three power and the liquid liquid angle and the sine angle of the blade placement angle. The ratio of impeller to population diameter is equal to the ratio of unit diameter (when the same inlet diameter coefficient is KO), and the value is

If the width of impeller is directly proportional to the inlet diameter, the relationship is correct. However, in the design of solid-liquid mixture pump, in addition to the flow rate and head, the minimum allowable size of the cross-section is also given, that is, when the speed changes, the cross-section size, including the impeller width, should be kept constant. Therefore, when evaluating the effect of rotational speed on wear, it is of practical significance that the width of impeller B is constant except for Q = const and H = const. At this time, the ratio of axle velocity to D, B product is inversely proportional to cna2/c1o=(n2/m)/0.

Therefore, the entrance velocity triangle is not similar. Because the circumferential velocity is inversely proportional to the second-third power of the rotational speed, the ratio of relative velocity (unin/un.n) < n/m) is 0. It is absolutely certain that when the rotational speed decreases, the liquid flow angle B. increases, i.e. hinl. / ing. > 1n [according to formula (3-7-4)], which will lead to an increase in wear. Thus, the ratio of linear wear of blade population to rotational speed is a function of the rotational speed.

According to the analysis of relative velocity value, the wear on the blade face and the wear on the blade outlet can not be evaluated.

For the solid particle concentration on the blade front is not constant and not equal to the average concentration, the wear is not only related to the velocity, but also to the particle concentration. Therefore, to determine the influence of impeller speed on blade surface wear, not only the relative velocity but also the concentration change of solid-liquid mixture near the worn surface should be considered.

In order to calculate the relative velocity of liquid flow at the exit edge of blade under the most severe wear, the change of velocity triangle is analyzed when the speed decreases, that is, when the specific speed decreases. In this case, the circumferential velocity U2 and radial partial velocity Cn at the impeller outlet decrease (due to the increase of diameter D at Q= onst), but C. increases and the relative velocity W at the impeller outlet decreases, which will lead to lower wear.

Since the above calculation results of velocity and wear can be obtained, they can be used to a certain degree of approximation.

According to the analysis of the projection of the total acceleration in the tangential direction of the circumference [Formula (3-7-3)], the relationship between the concentration of solid particles on the blade face and the rotational speed can be determined, and the redistribution intensity of the concentration of particles in the flow passage between the blades is related to the tangential acceleration. The maximum of the three components of acceleration AR is usually the first item on the right side of equation (3-7-3), which generally determines the aT value. When the speed decreases, the second and third terms decrease, and the second is due to the increase of the length of the impeller passage. The third is due to the increase of the impeller size including the radius of curvature Ru of the blade, but the value of the third term is much smaller than that of the first two terms.

II. THE EFFECT OF SOLID PARTICLE CONCENTRATION

In further analysis, the second and third terms of equation (3-7-3) are not considered, and the concentration of solid particles in the flow passage between blades is proportional to ar. Therefore, at different rotational speeds, the ratio of the concentration of particles on the blade front is equal to the ratio of their settling velocity in the corresponding acceleration field.

According to formula (3-7-2) and formula (3-7-5), considering the change of relative velocity and solid particle concentration, the linear wear ratio is obtained when the rotational speed changes.

Determine the change of linear wear when the speed decreases, for example, when the speed decreases by 1/3 (from n=1500r/min to n=1000r/min), that is, the linear wear at the blade outlet decreases roughly.

It's about a second lower.

Formula 3-7-7 and calculation results can be obtained by analyzing the phenomena occurring in the flow passage between blades and considering some assumptions. The complexity of these phenomena does not allow all factors affecting blade wear during cavitation at rotating speed to be taken into account. Therefore, in fact, when rotating speed decreases, the wear rate decreases. There may be some other reasons, which are the above reasons. For example, according to the analysis carried out, all the particles in the solid-liquid mixture are small. If the mixture contains large solid particles without affecting the wear of the blade working face (or face to face), the reduction of wear due to the decrease of rotational speed will be quite small. Here, the decrease of rotational speed will lead to the increase of critical dimension D (according to formula d, -1.26.6N yuan), i.e. the increase of the small particles in the solid-liquid mixture which participate in the wear of the blade working face: at this time, the increase of wear, i.e. the decrease of wear obtained according to formula 3-7-7, will be smaller.

No special tests have been carried out to check the relationship between impeller wear and speed (when all other parameters remain equal)