The fan speed will affect its parameters

The fan speed is an important factor affecting the performance of the fan. Speed changes, the fan flow, pressure head, the power will change, and the same flow rate, pressure head fan speed level will affect the size of the impeller size, the size of the diameter and width of the outlet.
  Fan speed relationship between the parameters and the main features are: flow and speed is proportional; proportional to the square of the speed pressure; power and speed proportional to the cube of side. Proportionality law called the fan above relationship