Parameters
Fan Type
Shutoff Pressure ΔP₀
800 Pa
Max Flow Rate Qmax
2.00 m³/s
Rotational Speed n
1450 rpm
System Settings
System Resistance K
200.0 Pa·s²/m⁶
Duct Diameter D
300 mm
Duct Length L
20.0 m
Fan Efficiency η
0.75
—
Operating Flow Q [m³/s]
—
Operating Pressure ΔP [Pa]
—
Efficiency η [%]
—
Shaft Power P [W]
—
Specific Speed Ns
Theory
Fan curve (parabolic approximation):
$$\Delta P_{fan} = \Delta P_0 \left(1 - \left(\frac{Q}{Q_{max}}\right)^2\right)$$System curve:
$$\Delta P_{sys} = K \cdot Q^2$$Shaft power & specific speed:
$$P_{shaft} = \frac{Q \cdot \Delta P}{\eta}, \quad N_s = \frac{n\sqrt{Q}}{\Delta P^{3/4}}$$Affinity laws: $Q \propto n$, $\Delta P \propto n^2$, $P \propto n^3$
Engineering Note: If the operating point falls on the right-descending portion of the fan curve, unstable operation (surging) may occur. For parallel or series fan configurations, recalculate the composite performance curve to find the new operating point.