Fan rotating stall reason

　　Fan works by converting the energy to achieve, namely: energy electromagnetic energy → → → kinetic energy to mechanical energy. The circuit principle is generally divided into many forms, using different circuits, there will be differences in the performance of the cooling fan.

　　To prevent accidents cooling fan failure caused unnecessary losses, we must make improvements from the design. Thus fundamental to dispel criticism, to change nature.

　　Cooling fan rotating stall is formed: cooling fan impeller structure, dimensions are in accordance with the rated air flow design, when the cooling fan in the normal air flow work gas into the direction of the impeller inlet mounting angle consistent with the blade air volume, gas may be smooth into the impeller, the impeller when entering the gas flow is less than the rated flow, the radial velocity of the gas into the impeller is reduced, the gas flow into the direction of the relative angular speed of the impeller is reduced, and thus the installation angle of the blade inlet is not consistent. Cooling fan blades in the processing and installation, due to various reasons can not have a blade shape and the same mounting angle. Thus, changes in the operating conditions when leaving the flow direction deviates, in each blade inlet angle of attack can not be identical. If a blade angle of attack at the entrance reaches a critical value, the first place on the blade stall, but not all of the blades simultaneously stall occurs, this phenomenon be continued, so that stall caused by the blockage area along with advancing in the opposite direction of rotation of the impeller, which produce the so-called "rotating stall" phenomenon. Cooling fan into the unstable conditions district run, will produce a number of rotating stall area to the impeller. Each time through the blade stall area would be the role of a exciting force, thereby allowing the blade to resonate. In this case, the dynamic stress increases blade may cause blade breakage, so from the absolute reference frame outside the impeller, the stall area or rotated in the direction of rotation of the impeller, causing the mechanism of rotating stall, rotating stall in the pressure generated by the impeller fluctuations occur rotor excitation abnormal vibration excitation force, the excitation force size and the size of the gas molecular weight, they are proportional to the relationship, the greater the molecular weight, the greater the incentive force. Fan

　　Rotor rotating stall frequency: When cooling fan normal operation, with the direction of the impeller rotor is in the same direction, an exception occurs when the fluid direction, the rotor is abnormal vibration. So which is caused by the cooling fan rotating stall reasons.