Tube axial fan's operation inspection

Operation inspection of tube axial fan

When the tube axial fan is running, it mainly monitors the current of the motor. The current is not only the mark of the fan load, but also the prediction of some abnormal changes. In addition, always check whether the vibration of motor and fan is normal and whether there is friction and abnormal sound. For fans running in parallel, pay attention to check whether the fans are running in surge State. During normal operation, the machine should be shut down for detection in case of the following environments:

1. tube axial fan produces strong vibration or collision sound;

2. The motor current suddenly rises and exceeds the rated current of the motor;

3. The temperature of motor bearing rises sharply.

Tube axial fan operation start

The operation of tube axial fan depends on the drive of motor. In fact, any equipment is the same. If you want to operate, you must have a similar "engine". When selecting the motor of tube axial fan, it is always hoped that the motor can drive the impeller to reach the rated speed quickly and work normally. The starting of motor includes the whole process of power on starting and acceleration. Its starting mode is divided into full pressure starting and reduced pressure starting.

To reasonably select the starting method of the motor, we must make a specific analysis according to the capacity of the power supply network, the requirements of the mechanical load on the starting torque, the characteristics of the motor itself and other factors, in order to obtain the specified starting time. For example, the capacity of the power grid is very large, and the starting current of the motor will not cause a significant voltage drop on the power grid. In addition, if the control lines and equipment of the power grid allow a large enough starting current for a short time, full voltage starting can be adopted; If the torque required by the fan during starting is not large, and the power grid capacity is not large compared with the motor, the main consideration is how to reduce the starting current and adopt reduced voltage starting.

Noise analysis of tube axial fan

The total noise level of the fan is directly proportional to the sixth power of the blade speed. According to the analysis, the fan noise source is basically dipole. It can be further deduced that the noise is caused by the pulse force of the blade acting on the air flowing through the fan. It can be considered that there are two discrete frequency noise sources of the fan, one is the propeller noise caused by the pressure field with the movement of the rotor blades, and the other is the blade pulsation noise caused by aerodynamic interference. The distance between the moving and stationary blades is an important factor of interference noise.

When this distance is very small, the changes of potential flow and wake will have an impact, and the blades may also act as a sound barrier to strengthen the sound radiation generated by the lift pulsation on on the blades adjacent to the blade row. This effect depends on the ratio of the acoustic wave wavelength related to the lift pulsation to the blade size as a barrier. In the frequency range where the ratio is greater than 2, the change of radiation intensity caused by this effect is the most significant. Therefore, when the upstream and downstream of a blade that radiates noise have the same number of blades, and each blade in the two rows of blades meets a rotor blade at the same time to form a sound barrier on both sides of the source, the impact will be stronger.