AF泡沫泵因?yàn)楣ぷ鼽c(diǎn)M處泵的揚(yáng)程

AF泡沫泵之所以能夠在M點(diǎn)穩(wěn)定工作,是因?yàn)楣ぷ鼽c(diǎn)M處泵的揚(yáng)程與管路裝置需要的信需要能頭相等，即單位質(zhì)量液體經(jīng)過泵所得到的能頭等于把單位質(zhì)量液體自吸液罐輸送到排液罐所需的能頭。
    假如泵在比M點(diǎn)流量大的M’點(diǎn)工作.如圖1- 42所示，則這時(shí)泵提供的揚(yáng)程H’小于管路裝置所需能頭h’(假設(shè)管路特性不變)，說明把工作點(diǎn)M’處對(duì)應(yīng)的液體流量從吸液罐輸送到排液罐時(shí)所需的能頭大于液體從泵中獲得的能頭。這時(shí)液體能頭不足，必然導(dǎo)致流速減慢，使流量減小,工作點(diǎn)M’沿泵揚(yáng)程性能曲線向M點(diǎn)移動(dòng)。
    反之，如果泵在流量小于M點(diǎn)的M"點(diǎn)工作，則管路裝置所需能頭h"小于泵的揚(yáng)程H"，液體從泵中獲得的能頭除用于將液體從吸液罐輸送到排液罐所需的能頭外，還有部分剩余，因此將使管路內(nèi)液體加速流動(dòng)，流量增大,M"點(diǎn)向M點(diǎn)移動(dòng)。
    可見,M點(diǎn)是流量平衡和能量平衡的唯一穩(wěn)定工作點(diǎn)，此點(diǎn)必然是泵的揚(yáng)程性能曲線與管路特性的交點(diǎn)。
2)解析法
    圖解法具有直觀簡單的特點(diǎn)，但對(duì)于復(fù)雜的工程計(jì)算，利用計(jì)算機(jī)進(jìn)行解析計(jì)算求工作點(diǎn)更方便準(zhǔn)確。將式(1-72)式(1 - 73)聯(lián)立，同時(shí)取m=0,有:
                                H=A- BQ2

h=Hpot+kQ

                                 H=h

即可求得工作點(diǎn)。

[例1-5]如圖1-5所示，已知離心泵的H-Q性能見表1-9，管路特性為h= 20+274Q2， 試用解析法求系統(tǒng)工作點(diǎn)。AF泡沫泵
    解:首先將流量換算為m3/s,見表1- 10。

AF foam pump because of the pump head at M.
The reason why the AF foam pump works at M point is that the pump head at the working point M is equal to the letter required by the pipeline device, that is, the energy head of the unit mass liquid passing through the pump is equal to the energy head needed to deliver the unit mass liquid self aspirating tank to the liquid discharge tank.
If the pump works at M 'point with larger flow than m point, as shown in Fig. 1-42, then the head H' provided by the pump is less than the energy head H 'required by the pipeline device (assuming that the characteristics of the pipeline remain unchanged), which means that the energy head required for conveying the corresponding liquid flow at M' point from the suction tank to the discharge tank is greater than the energy head obtained from the pump. At this time, the liquid head is insufficient, which will inevitably slow down the flow rate, reduce the flow rate, and move the working point m 'along the pump head performance curve to point M.
On the contrary, if the pump works at M "point with flow less than m point, the energy head H" required by the pipeline device is less than the head h of the pump. The energy head obtained from the pump is not only used to transfer the liquid from the suction tank to the discharge tank, but also has some surplus. Therefore, the liquid in the pipeline will accelerate the flow, the flow will increase, and the M "point will move to m point.
It can be seen that point m is the only stable working point of flow balance and energy balance, which must be the intersection of pump head performance curve and pipeline characteristics.
2) analytical method
The graphic method is intuitionistic and simple, but for complex engineering calculation, it is more convenient and accurate to calculate the working point by computer. Combine formula (1-72) (1-73), and take M = 0 at the same time, as follows:
H=A- BQ2
H=Hpot+kQ
H=h
The working point can be obtained.
[example 1-5] as shown in Figure 1-5, it is known that the H-Q visibility of centrifugal pump is shown in table 1-9, and the pipeline characteristic is h = 20 + 274q2. Try to find the working point of the system by analytical method. AF foam pump
Solution: first, convert the flow to m3 / s, as shown in table 1-10.