Regarding the surge phenomenon of crossflow fans, I can provide you with some analysis and suggestions:

Surge is an unstable working state that crossflow fans are prone to under certain working conditions. It usually manifests as periodic fluctuations in the fan outlet pressure and air volume, and in severe cases it may even cause damage to the fan.

The main causes of surge include:

1. Poor air intake:

- If there is a blockage at the fan inlet or the air intake conditions are poor, the stable working range of the fan will be reduced, which may easily cause surge.

2. Drastic load changes:

- If the system load changes too much or too quickly, it will exceed the adaptability range of the fan and cause surge.

3. Unreasonable impeller design:

- If the geometric parameters of the impeller, such as blade shape and blade pitch, are improperly designed, it may also reduce the stable working area of ​​the fan.

4. Pipeline resonance:

- If the fan outlet pipeline has a resonance frequency close to the fan speed, it will also cause surge.

In view of these reasons, the following measures can be taken to solve the surge problem:

1. Optimize the intake conditions, such as increasing the inlet expansion section, etc.

2. Adjust the load change speed and slow down the load change rate.

3. Optimize the impeller design parameters to improve the stable working range of the fan.

4. Adjust the outlet pipeline structure to avoid the resonance frequency.

5. Add feedback control in the speed control system to improve the stability of the fan.

In summary, solving the surge problem of the cross-flow fan requires analysis and optimization from multiple angles. If you have further questions, please feel free to consult me.