Possibility and importance of improving centrifugal fan impeller
Although increasing the speed of the centrifugal fan can increase the air volume of the fan approximately in a straight line, this needs to change the basis of the driving equipment of the centrifugal fan, which requires higher requirements for the inlet dust, water and impeller balance accuracy of the centrifugal fan, otherwise it cannot be achieved. Changing the number of impeller blades will not cause changes in the main structural dimensions of the fan, and the impact on the total pressure of the fan is relatively small. The speed of the fan has not increased, and the transformation period is short, which can save the investment of the transformation. However, the disadvantage is that the operating efficiency of the fan will change greatly, increasing the energy consumption, but through the coordination design of the blade angle, the power loss can be reduced.
According to the professional fan theory, the centrifugal fan cannot determine the optimal number of blades with the same mathematical method as the axial flow fan. Therefore, when we design the blade channel, the principle of determining the number of blades is to ensure the reasonable flow of the air flow, so that the air flow does not separate or generate eddy current. The optimal number of blades of centrifugal impeller can only be known through experiments. According to professional experiments, changing the actual width of the blade passage will cause great changes in the angle of the relative speed and the absolute speed of the air flow. The seasonal speed of partially filled and completely filled blade passage will reduce the blade pitch and increase the number of blades under the condition of constant speed, which will cause the relative speed W3 to increase, This results in a significant increase in the radial velocity of 2m. According to the theoretical flow calculation formula v=c2mPd2b2 of the fan, when the impeller diameter D2, the impeller width b2 and the circumferential velocity u2 are constant, the increase of c2m will be proportional to the theoretical flow of the fan.
The centrifugal fan can significantly increase the air supply volume by increasing the number of impeller blades, and to a large extent, it can save our money. At present, the optimal number of impeller blades can only be determined by experiments. Not every fan can increase the air volume by increasing the number of impeller blades. Increasing the number of impeller blades will cause an increase in impact loss, a decrease in pressure rise, and a decrease in fan efficiency, Therefore, in many cases, the number of blades cannot be increased too much by 132.d1, the power of the main shaft increases, and the bearing load increases accordingly. The strength of the sliding bearing must be rechecked during design, and the operation must be controlled at the rated speed.
