泡沫泵液體在葉輪中的流動(dòng)
    液體在葉輪流道內(nèi)的流動(dòng)情況較為復(fù)雜，為了便于從理論上進(jìn)行分析，通常有以下三點(diǎn)假設(shè):
    (1)液體在葉輪中的流動(dòng)是穩(wěn)定流動(dòng)，即流場(chǎng)不隨時(shí)間變化而變化。

(2)通過(guò)葉輪的液體是理想液體，即液體在葉輪內(nèi)流動(dòng)時(shí)無(wú)能量損失。

(3)葉輪由無(wú)限多、無(wú)限海的葉片組成，則液體在葉輪流道間作相對(duì)運(yùn)動(dòng)時(shí).其運(yùn)動(dòng)軌跡與葉片曲線的形狀完全一致,葉輪相同半徑圓周上液體質(zhì)點(diǎn)的速度大小相等。
    葉輪旋轉(zhuǎn)時(shí)，波體在葉輪內(nèi)一方面沿者葉片向外作相對(duì)于葉片的相對(duì)運(yùn)動(dòng)，其運(yùn)動(dòng)速度稱為相對(duì)速度，用矢量w表示，在無(wú)限多葉片的假設(shè)下.其方向與葉片相切如圖1-6(a)所示，同時(shí)液體又隨著葉輪一起旋轉(zhuǎn)作園周運(yùn)動(dòng)(牽連運(yùn)動(dòng))，其運(yùn)動(dòng)速度府為圓周速度(牽連速度) 用矢量u表示，其大小和方向與葉輪圓周速度相同，如圖1- 6(b)所示。

因此，液體在葉輪中的運(yùn)動(dòng)是一種由圓周運(yùn)動(dòng)和相對(duì)運(yùn)動(dòng)兩者合成的運(yùn)動(dòng)，其運(yùn)動(dòng)速度稱為絕對(duì)速度,用矢量c表示，如圖1 - 6(c)所示，則c等于相對(duì)速度w和圓周速度u的矢量和，即
                           c=u+w
由這三個(gè)速度矢量組成的矢量圖稱為速度三角形，如圖1-7所示。
    絕對(duì)速度c可分解成兩個(gè)分量:一個(gè)是與圓周速度垂直的分量，以c,表示，稱為液體絕對(duì)速度的徑向分速，或軸面速度;另一個(gè)是與圓周速度平行的分量，以Cu表示,稱為液體絕對(duì)速

度的周向分速。

液體速度間夾角與葉輪幾何參數(shù)可用下列符號(hào)表示:

a----絕對(duì)流動(dòng)角，為液體絕對(duì)速度方向與圓周速度方向間的夾角;

β----相對(duì)流動(dòng)角，即液體相對(duì)速度方向與圓周速度反方向間的夾角;

βA--葉片角，即葉片在該點(diǎn)的切線與圓周速度反方向間的夾角。

在葉片無(wú)限多的假設(shè)條件下，相對(duì)流動(dòng)角與葉片角一致，即:β= βA。 泡沫泵

采用下角標(biāo)1.2分別表示葉片進(jìn)口和葉片出口處的參數(shù)，采用下角標(biāo)∞表示液體在葉片數(shù)為無(wú)限多的葉輪中流動(dòng)時(shí)的參數(shù)。

Flow of foam pump in impeller

The flow of liquid in the impeller passage is complex. In order to facilitate the theoretical analysis, there are usually three assumptions as follows:

(1) The flow of liquid in impeller is stable, that is, the flow field does not change with time.

(2) The liquid passing through the impeller is an ideal liquid, that is, there is no energy loss when the liquid flows in the impeller.

(3) The impeller is composed of infinite and infinite sea blades. When the liquid moves in the impeller channel, its trajectory is exactly the same as the shape of the blade curve, and the speed of the liquid particles on the same radius circle of the impeller is equal.

When the impeller rotates, on the one hand, the wave body moves relative to the blade outwards along the blade inside the impeller, and its moving speed is called relative speed, which is represented by vector W. under the assumption of infinite number of blades, its direction is tangent to the blade as shown in Figure 1-6 (a). Meanwhile, the liquid rotates with the impeller to make circular motion (implicated motion), and its moving speed is circular speed (implicated speed) Represented by vector u, its size and direction are the same as the peripheral speed of impeller, as shown in Fig. 1-6 (b).

Therefore, the motion of the liquid in the impeller is a kind of motion composed of circular motion and relative motion. Its motion speed is called absolute velocity, which is represented by vector C, as shown in Figure 1-6 (c). Then C is equal to the vector sum of relative velocity W and circular velocity u, that is

C=u+w

The vector diagram composed of these three velocity vectors is called velocity triangle, as shown in Figure 1-7.

Absolute velocity C can be divided into two components: one is the component perpendicular to the circumferential velocity, expressed in C, which is called radial velocity of absolute velocity of liquid, or axial velocity; the other is the component parallel to the circumferential velocity, expressed in Cu, which is called absolute velocity of liquid

The circumferential velocity of degrees.

The angle between the liquid velocity and the geometric parameters of the impeller can be expressed by the following symbols:

A -- absolute flow angle, which is the angle between the absolute velocity direction of liquid and the circumferential velocity direction;

β - relative flow angle, that is, the angle between the relative velocity direction of the liquid and the reverse direction of the circular velocity;

β a -- blade angle, that is, the angle between the tangent line of the blade at this point and the reverse direction of the peripheral speed.

Under the assumption of infinite number of blades, the relative flow angle is the same as the blade angle, that is, β = β a. Foam pump

The lower angle scale 1.2 is used to represent the parameters of blade inlet and blade outlet respectively, and the lower angle scale ∞ is used to represent the parameters of liquid flowing in the impeller with infinite number of blades.