The meaning of multi-stage centrifugal pump performance curve
The introduction of the D-type multistage centrifugal water pump involves performance parameter maps. Many novices often do not understand the meaning of the atlas in practice. Today, let's analyze the magnitude of the performance curve and teach you to read the performance curve of D-type multistage centrifugal pump!
D-type multistage centrifugal water pump performance parameters such as flow Q, head H, shaft power N, speed n, efficiency η exist a certain relationship. The relationship between the changes in magnitude between them is represented by a curve, which is called the performance curve of the pump. The performance curve of the multistage centrifugal pump is the relationship curve between the basic performance parameters (flow rate, pressure head, power and efficiency) of the centrifugal pump at a fixed speed. The performance curve is measured at a fixed speed, which is only applicable to the speed, so the value of the speed is indicated on the characteristic curve. The mutual change relationship and mutual restriction between the performance parameters of the water pump: First, the forehead speed of the water pump is the prerequisite.
The performance curve of D-type multistage centrifugal water pump mainly has three curves: flow-head curve, flow-power curve, flow-efficiency curve.
1. Flow-head performance curve, it is the basic performance curve of centrifugal pumps. Centrifugal pumps with a specific speed of less than 80 have the characteristics of rising and falling (both convex in the middle and curved on both sides), which is called the hump performance curve. Centrifugal pumps with a specific speed between 80 and 150 have a flat performance curve. Centrifugal pumps with a specific speed above 150 have a steep drop performance curve. Generally speaking, when the flow rate is small, the head is high, and the head gradually decreases as the flow rate increases.
2. Flow-power curve The shaft power increases with the flow. When the flow Q = 0, the corresponding shaft power is not equal to zero, but a certain value (about 60% of normal operation). This power is mainly consumed in mechanical losses. At this time, the pump is full of water. If it runs for a long time, it will cause the temperature in the pump to rise continuously, and the pump casing and bearings will heat up. In severe cases, the pump body may be thermally deformed. The head is the maximum value. When the outlet valve is gradually opened, the flow rate will gradually increase, and the shaft power will also increase slowly.
3. Flow-efficiency curve Its curve is like the shape of a mountain. When the flow is zero, the efficiency is equal to zero. As the flow increases, the efficiency also gradually increases, but after increasing to a certain value, the efficiency decreases, and the efficiency has a The highest value is near the highest efficiency point, and the efficiency is relatively high. This area is called the high efficiency area.
