Centrifugal fan is essentially a variable flow and constant pressure device. When the rotating speed is constant, the pressure-flow theoretical curve of the centrifugal fan should be a straight line. Due to internal losses, the actual characteristic curve is curved.
The pressure generated in the centrifugal fan is greatly affected by changes in the temperature or density of the intake air. For a given intake air volume, the highest intake air temperature (lowest air density) produces the lowest pressure. For a given pressure and flow characteristic curve, there is a power and flow characteristic curve. When the blower runs at a constant speed When, for a given flow rate, the required power increases as the intake air temperature decreases.