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渣漿泵流動狀態的分界速度
    為了推廣實現懸浮液從一種狀態過設到另一狀態的條件，適當引用與牛頓流體的雷諾數相似的無因次量。具有很大實際意義的是與過渡到自模流動狀態相對應的雷諾數Re.

在液流自模狀志轉變的瞬時，速度足夠大，因而壓力損失足夠大，以便可以利用損失的簡化公式。
  水力摩據系數，在流動結構狀態所確定的損失和根據達西——威斯巴赫公式計算的損失相等的條件下可以得到
    結構流動狀態過渡到偽層流狀態的雷諾數對應值稱為極限雷諾數Rep。
    根據各種懸浮液(泥炭漿，磁鐵礦漿和黏土溶液)流動試驗研究結果得到:雖然懸浮液參數(密度，初始切應力，結構黏性)變化范圍很大，但雷諾數Rez值只在1950~3000之間相當窄范圍內變化(表2-3-1)。對于煤漿，根據B. B.特萊尼斯資料，從偽層流狀態過渡到紊流狀態所對應的雷諾數Re接近4000。
    在分界速度以、、加、o"時根據雷諾數Re"值確定流動狀態邊界。目前只能推薦懸浮液從一種流動狀態過渡到另一種狀態所對應的雷諾數Re近似值根據B.特萊尼斯資料，對于什維多夫狀態過渡到突漢體狀態(0>01)和賓漢體狀態過找到偽層流狀態(o>o1)所對應的煤漿雷諾數Re值分別等于10和3000
    從嚴格結構流動狀態過渡到偽層流狀態時的流選稱為極限速度v，此速度與管徑、流速特性和懸浮液密度有關，并從Re"表達式確定這個速度

為了估算極限速度的數量級，引用H.莫吉列夫斯基不同密度即有不同就變待性的磁鐵礦在管徑D= 105mm管內流動資料

引用懸浮液極限流速的概念，對于分析和描述泵的工作過程是必需的。 

在懸浮液速度超過速度v(參閱圖2-3-4)時，流動狀態變為水力摩擦系數入恒定的自模狀態。這種狀態具有很大意義，因為在渣漿泵的過流部件流道中，在工作狀態時大概會碰到。根據試驗資料，與過渡到自模狀態所對應的雷諾數Re值，對于黏土和煤漿，大于40000，對于磁鐵礦漿，大于11000。
    懸浮液偽層流狀態，甚至在相當大的速度時也相當穩定，如果θ和η很大。在圖2-3-4上用虛線示出清水在紊流狀態時損失曲線。從圖上可知，在具有較小流速的偽層流狀態時損失遠大于它們假定具有同樣速度的紊流狀態時的損失。水泵在小于額定流量時工作，在葉輪流道內可能產生懸浮液偽層流狀態或者甚至結構流動狀態，這將導致葉輪內水力損失相對增大，在水泵特性曲線上稱為所謂的“塌陷”。 這種現象將在第三篇第六章中詳細研究。

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.