Influencing Factors and Solutions of Cavitation Erosion Allowance in Mixed Flow Pump

Category: Water pump knowledge

2024-08-09

mixed flow pumpThe cavitation margin refers to the ability of the mixed flow pump to allow a certain degree of gas intrusion without causing cavitation during the working process. Cavitation is one of the common faults of mixed flow pump, which will reduce the efficiency of the pump, increase the noise and even seriously damage the pump equipment. Therefore, it is very important to study the influencing factors and solutions of cavitation margin to ensure the normal operation of mixed-flow pump.

When the pump inlet pressure drops below the saturated vapor pressure, the gas in the liquid is gradually generated and instantly collapses at the pressure increase, resulting in violent vortex and impact sound. Such alternation will cause damage to the pump body, impeller, guide vane and other components. During the operation of mixed-flow pump, cavitation margin is an important parameter, which affects the performance and service life of the pump. The following is a discussion of the influence factors and solutions of the cavitation margin of the mixed flow pump.

1. factors affecting cavitation margin of mixed-flow pump

1. Flow rate and flow rate: high flow rate and large flow rate can easily lead to pressure fluctuations in the pump, increasing the risk of cavitation.

2. Gas content: The higher the gas content in the liquid, the greater the possibility of cavitation.

3. Inlet pressure: Inlet pressure is too low will increase the risk of cavitation.

4. Structural design of the pump: Unreasonable pump body structure may cause fluid dynamics instability and aggravate cavitation.

Calculation Method of 2. Mixed Flow Pump NPSH

NPSH refers to the difference between the pump and NPSH at the starting point of installation. Generally speaking, it is the safety margin that can prevent the mixed flow pump from cavitation. The specific calculation method is:

NPSH = Hs-HNPSHr

Among them, Hs is the liquid level corresponding to the saturated steam pressure, and HNPSHr is the net suction margin required by the pump. This value can refer to the performance parameter table of the pump.

3. Solution

1. Optimize the flow rate and flow: according to the actual demand and the rated parameters of the pump, set the flow rate and flow reasonably to avoid too high or too low operating conditions.

2. Reduce the gas content: Before the liquid enters the pump, take degassing measures, such as setting up a degassing device to reduce the gas content in the liquid.

3. Increase the inlet pressure: when conditions permit, appropriately increase the inlet pressure to reduce the risk of cavitation.

4. Improve the structural design of the pump: according to the principle of fluid dynamics, optimize the structure of the pump body and enhance the ability of anti-cavitation.

5. Use anti-cavitation materials: select materials with excellent anti-cavitation performance to make the flow parts of the pump to improve the durability of the pump.

6. Regular inspection and maintenance: regular inspection and maintenance of the mixed flow pump, timely detection and treatment of cavitation problems, to ensure the good operation of the pump.

7. Install the exhaust valve: Install the exhaust valve in the appropriate position of the pump to discharge the gas in the pump in time to reduce the risk of cavitation.

8. Control the operating temperature: too high operating temperature may lead to increased liquid evaporation, increase the risk of cavitation. Therefore, the operating temperature of the mixed-flow pump should be reasonably controlled.

In short, the cavitation margin of the mixed-flow pump is affected by many factors, including flow rate, flow rate, gas content, inlet pressure and pump structure design. In order to solve these problems, we can take a series of measures, such as optimizing the flow rate and flow, reducing the gas content, increasing the inlet pressure, improving the structural design of the pump, using anti-cavitation materials. Through reasonable operation and maintenance, we can ensure the good operation of the mixed-flow pump and extend its service life.

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