If the performance curve of the wear-resistant and corrosion-resistant centrifugal pump has a hump, it will be unstable during operation, which is not allowed. Therefore, when designing the pump, measures must be taken to make the performance curve of the wear-resistant and corrosion-resistant centrifugal pump No hump. This article discusses the shape of the wear-resistant and corrosion-resistant centrifugal pump performance curve, the factors affecting the shape of the performance curve, and the measures to eliminate the hump.
Wear-resistant and corrosion-resistant centrifugal pump performance curve shape, influencing factors and measures to eliminate hump:
Common wear-resistant and corrosion-resistant centrifugal pump performance curves can be divided into three types: flat, steep and hump, as shown in Figure 1.
Performance curve of wear-resistant and corrosion-resistant centrifugal pump
1. A steep drop in performance curve
The performance curve with this shape is suitable for systems with small changes in flow and large changes in head (head), or systems that require small changes in flow when the pressure head fluctuates.
2. Flat performance curve
The performance curve of this shape is suitable for a system with a large pump flow adjustment range and a small change in pressure head requirements.
3. Performance curve with hump
The pump with the performance curve of this shape may have unstable working conditions in the running towel, which will affect the safe operation of the pump. For this kind of performance curve with hump, it is generally stipulated that the working point head must be less than the closed dead point head to avoid the pump running under unstable conditions.
Factors that affect the shape of the pump performance curve and measures to eliminate hump: There are many factors that affect the shape of the pump performance curve. In general, there are the following factors:
(1) Blade number Z; (2) Blade outlet placement angle; (3) Pump body throat area; (4) Impeller outlet width; (5) Blade shape; (6) Volute tongue gap; (7) Pressure Water chamber area: (8) blade outlet thickness; (9) liquid pre-rotation at the impeller inlet; (10) specific revolutions, etc.
In terms of eliminating the hump of the pump performance curve, a lot of experimental research work has been done at home and abroad, and many measures and methods to eliminate or reduce the hump have been proposed. Generally, there are the following:
(1) Reduce the installation angle of the blade outlet (2) Reduce the number of blades Z (3) Reduce the area of the pressurized water chamber and increase the shut-off head (4) Pre-rotation of the liquid at the inlet of the impeller (if the outlet angle of the back guide vane is less than 90 Degree.), make the performance curve drop sharply (5) reduce the gap between the tongues (6) set a rectifying grid (baffle) in the suction pipe (7) set an inducer, etc.
These measures and methods can be used alone or in combination. No matter which measures are taken, the wear-resistant and corrosion-resistant centrifugal pumps must consider the requirements of head, efficiency and cavitation performance, and cannot afford to lose sight of the other.
