The air volume of centrifugal fan can be adjusted in many different ways, including inlet, outlet valve, cochlear air valve, inlet vane, rotor, rotary number and so on. For various types of fans, due to different adjustment methods, the resulting energy-saving effect will be very different.
If the air volume of centrifugal fan is regulated by outlet valve, the main change is the characteristic of pipe network, not the characteristic of fan. The range of air flow regulation is usually under all conditions under the rated performance curve of the fan.
If the inlet air valve is used to adjust the air volume of the centrifugal fan, then when the pipe is arranged on the suction side of the fan, its regulating principle is the same as that of the outlet air valve; but when the pipe is arranged on the exhaust side of the fan, it changes the inlet pressure of the fan. To change the fan performance curve, so the economy is good.
There is a spiral air valve of the centrifugal fan is adjusted by changing the fan outlet area, to change the characteristics of the wind turbine, compared to the volume reduction, power change is small, energy saving is not significant. The two regulation, the principle can be used in all conditions rated under the curve, the surge point offset therefore, to the small flow direction, widely used in wind turbines generally have a fixed speed.
The centrifugal fan can also adjust the air volume through the inlet blade. In fact, by adjusting the blade, the direction of the air flow of the suction impeller can be changed, and the performance curve of the fan can be changed. When the inlet guide vane angle is zero, all the working conditions below the performance curve can be realized, and the negative rotation adjustment of the inlet air flow can increase the pressure and flow rate of the fan, but there are certain limits in the adjustment range.http://www.jnblower.com/