渣浆泵流动状态的分界速度
    为了推广实现悬浮液从一种状态过设到另一状态的条件，适当引用与牛顿流体的雷诺数相似的无因次量。具有很大实际意义的是与过渡到自模流动状态相对应的雷诺数Re.

在液流自模状志转变的瞬时，速度足够大，因而压力损失足够大，以便可以利用损失的简化公式。
  水力摩据系数，在流动结构状态所确定的损失和根据达西——威斯巴赫公式计算的损失相等的条件下可以得到
    结构流动状态过渡到伪层流状态的雷诺数对应值称为极限雷诺数Rep。
    根据各种悬浮液(泥炭浆，磁铁矿浆和黏土溶液)流动试验研究结果得到:虽然悬浮液参数(密度，初始切应力，结构黏性)变化范围很大，但雷诺数Rez值只在1950~3000之间相当窄范围内变化(表2-3-1)。对于煤浆，根据B. B.特莱尼斯资料，从伪层流状态过渡到紊流状态所对应的雷诺数Re接近4000。
    在分界速度以、、加、o"时根据雷诺数Re"值确定流动状态边界。目前只能推荐悬浮液从一种流动状态过渡到另一种状态所对应的雷诺数Re近似值根据B.特莱尼斯资料，对于什维多夫状态过渡到突汉体状态(0>01)和宾汉体状态过找到伪层流状态(o>o1)所对应的煤浆雷诺数Re值分别等于10和3000
    从严格结构流动状态过渡到伪层流状态时的流选称为极限速度v，此速度与管径、流速特性和悬浮液密度有关，并从Re"表达式确定这个速度

为了估算极限速度的数量级，引用H.莫吉列夫斯基不同密度即有不同就变待性的磁铁矿在管径D= 105mm管内流动资料

引用悬浮液极限流速的概念，对于分析和描述泵的工作过程是必需的。 

在悬浮液速度超过速度v(参阅图2-3-4)时，流动状态变为水力摩擦系数入恒定的自模状态。这种状态具有很大意义，因为在渣浆泵的过流部件流道中，在工作状态时大概会碰到。根据试验资料，与过渡到自模状态所对应的雷诺数Re值，对于黏土和煤浆，大于40000，对于磁铁矿浆，大于11000。
    悬浮液伪层流状态，甚至在相当大的速度时也相当稳定，如果θ和η很大。在图2-3-4上用虚线示出清水在紊流状态时损失曲线。从图上可知，在具有较小流速的伪层流状态时损失远大于它们假定具有同样速度的紊流状态时的损失。水泵在小于额定流量时工作，在叶轮流道内可能产生悬浮液伪层流状态或者甚至结构流动状态，这将导致叶轮内水力损失相对增大，在水泵特性曲线上称为所谓的“塌陷”。 这种现象将在第三篇第六章中详细研究。

Boundary Speed of Slurry Pump Flow State

In order to popularize the condition of suspension from one state to another, dimensionless quantity similar to Reynolds number of Newtonian fluid is appropriately quoted. The Reynolds number Re corresponding to the transition to the mode flow state is of great practical significance.

In the instantaneous transition of liquid flow self-pattern, the velocity is large enough, so the pressure loss is large enough to make use of the simplified formula of loss.

The hydraulic mooring coefficient can be obtained under the condition that the loss determined by the flow structure state is equal to that calculated by the Darcy-Wiesbach formula.

The Reynolds number corresponding to the transition from structural flow state to pseudo-laminar flow state is called the limit Reynolds number Rep.

According to the experimental results of various suspensions (peat slurry, magnetite slurry and clay solution), although the parameters of suspension (density, initial shear stress, structural viscosity) vary widely, the Rez number varies only in a narrow range from 1950 to 3000 (Table 2-3-1). For coal slurry, according to B. B. Trennis data, the Reynolds number corresponding to the transition from pseudo-laminar state to turbulent state is close to 4000.

The boundary of flow state is determined according to Reynolds number Re when the boundary velocity is -, plus -, o. At present, only the Reynolds number Re approximation corresponding to the transition of suspension from one flow state to another can be recommended. According to B. Trenis data, the Reynolds number Re values of coal slurry corresponding to the transition from Shdov state to Turkish state (0 > 01) and Bingham state (o > o1) are equal to 10 and 3000 respectively.

Limit velocity V is chosen when the flow state transits from a strictly structured state to a pseudo-laminar state. This velocity is related to the diameter of the pipe, the velocity characteristics and the suspension density. The velocity is determined from the Re e­xpression.

In order to estimate the magnitude of the limit velocity, the flow data of magnetite with different densities (i.e., different readiness) in pipe diameter D= 105mm are quoted.

It is necessary to introduce the concept of the limit velocity of suspension for analyzing and describing the working process of the pump.

When the suspension velocity exceeds the velocity v (see Fig. 2-3-4), the flow state becomes a self-model state with constant hydraulic friction coefficient. This state is of great significance, because in the flow passage of the flow components of the pump, it will probably be encountered in the working state. According to the experimental data, the Reynolds number Re corresponding to the transition to the self-model state is greater than 40 000 for clay and coal slurry and 11 000 for magnetite slurry.

The pseudo-laminar flow of suspension is quite stable even at considerable velocities, if theta and_are very large. On Fig. 2-3-4, the loss curve of clear water in turbulent state is shown by dotted lines. It can be seen from the graph that the loss in pseudo-laminar flow with small velocity is much greater than that in turbulent flow with the same velocity. When the pump operates at less than the rated flow rate, the pseudo-laminar flow of suspension or even the structural flow state may occur in the impeller passage, which will lead to the relative increase of hydraulic loss in the impeller, which is called "collapse" in the pump characteristic curve. This phenomenon will be studied in detail in Chapter 6 of Chapter 3.