Fan Laws Calculator

This calculator applies the Fan Laws to predict changes in fan performance (Flow, Pressure, Power) when altering fan speed, impeller diameter, or air density. It's a fundamental tool for system design and troubleshooting.

Key Inputs:

Unit System: Select Metric (m³/s, Pa, kW, RPM, mm, kg/m³) or Imperial (CFM, in.wc, HP, RPM, inch, lb/ft³).
Original Fan Performance: Initial Flow Rate (\(Q_1\)), Static Pressure (\(SP_1\)), and Power (\(P_1\)).
Original Fan Parameters: Initial Fan Speed (\(N_1\)) and Impeller Diameter (\(D_1\)).
Change Parameters:
- New Fan Speed (\(N_2\)): If fan speed changes (original diameter).
- New Impeller Diameter (\(D_2\)): If impeller diameter changes (original speed).
- New Air Density (\(\rho_2\)): If air density changes (e.g., due to temperature/altitude, keeping N & D same initially).

Calculated Outputs (New Performance):

Original Fan Efficiency (\(\eta_1\)): The efficiency of the fan at its original operating point.
New Flow Rate (\(Q_2\)): Predicted volumetric flow rate.
New Static Pressure (\(SP_2\)): Predicted static pressure (or head).
New Power (\(P_2\)): Predicted fan power consumption.

Unit System:

Calculation Type:

Original Fan Performance (\(Q_1, SP_1, P_1\))

Original Flow Rate (\(Q_1\)) (m³/s):

Original Static Pressure (\(SP_1\)) (Pa):

Original Power (\(P_1\)) (kW):

Original Air Density (\(\rho_1\)) (kg/m³):

Original Fan Parameters (\(N_1, D_1\))

Original Fan Speed (\(N_1\)) (RPM):

Original Impeller Diameter (\(D_1\)) (mm):

New Fan Parameters (\(N_2, D_2, \rho_2\))

New Fan Speed (\(N_2\)) (RPM):

Calculation Results

Parameter	Value