由式(1-21)可知，离心泵内有限叶片数条件下的理论扬程为Ht=pHro离心泵的滑移系数与流量无关,即μ为常数。将H1。-Q1(曲线1)上各点纵坐标均乘以μ,由于滑移系数μ的值小于1,即可得到叶片数目有限时离心泵的理论扬程Hr-Qτ关系曲线(曲线2)。因实际液体得到的能头为H= Ht-Hf-Hsh，故从理论扬程Hr- QT(曲线2)中减去同一流量下对应的摩擦损失Hf,得曲线3,再减去冲击损失Hsh,就可得到实际扬程与流量的关系H-Qr(曲线4)。
以H-Qt线(曲线4)上工况点C为例，过C点作水平线与H -q线(曲线8)交于点A,与纵坐标交于点B,AB线段的长度即为C点扬程所对应的泄漏量q。将C点向左平移q得到D,点D即为考虑流量泄漏损失后的工况点。从流量一扬程曲线H一QT的横坐标数值中减去相应的泄漏量q，就可得到泵的流量一扬程曲线 H - Q线(曲线5)。渣浆泵
Characteristic curve analysis of slurry pump
The relationship curves of the head and flow, power and flow, efficiency and flow, and suction vacuum (or necessary cavitation) and flow of a centrifugal pump at a certain speed are called the working characteristic curves of the pump, which can reflect the performance characteristics of the pump.
1。 Head flow curve
According to Euler's formula, the theoretical lift of infinite blades under the assumption is shown in formula (1-16). In centrifugal pump, the outlet angle of impeller blade is generally less than 90 °. If the flow is taken as the abscissa and the lift as the ordinate, HX QR is a straight line inclined downward (Fig. 1-29 curve 1).
It can be seen from formula (1-21) that under the condition of limited number of blades in centrifugal pump, the theoretical head is HT = phro, and the slip coefficient of centrifugal pump is independent of flow, i.e., μ is constant. -The longitudinal coordinates of each point on Q1 (curve 1) are multiplied by μ. Since the value of slip coefficient μ is less than 1, the theoretical head hr-q τ relation curve (curve 2) of centrifugal pump with limited number of blades can be obtained. Since the energy head of the actual liquid is h = HT HF sh, the friction loss HF corresponding to the same flow rate is subtracted from the theoretical head hr-qt (curve 2), and then the curve 3 is obtained, and the impact loss SH is subtracted, then the relationship between the actual head and flow h-qr (curve 4) can be obtained.
Take point C on h-qt line (curve 4) as an example, cross point C as horizontal line and H-Q line (curve 8) to point a, and cross point B with ordinate。 The length of line AB is the leakage Q corresponding to the lift of point C。 Translate point C to the left and Q to get D。 point D is the operating point after considering the loss of flow leakage。 By subtracting the corresponding leakage Q from the abscissa value of the flow head curve h-qt, the flow head curve H-Q line (curve 5) of the pump can be obtained。 Slurry pump
It can be seen from the above analysis that the shape of H-Q curve is closely related to the peripheral velocity U2, outer diameter D2, blade angle and various resistance losses of impeller.