Impeller Tip Speed Calculator

Calculate peripheral tip speed and angular velocity for a rotating impeller or fan blade.

Turbomachinery · Kinematics

Inputs

Impeller diameter D (m)

Rotational speed N (rpm)

Theory

Key Formulas

ω = N × 2π / 60 [rad/s]

u₂ = ω × D / 2 [m/s]

hc = u₂² / (2g) [m] — centrifugal head

Hₑ = u₂² / g [m] — theoretical Euler head

Variables

N — rotational speed [rpm]
ω — angular velocity [rad/s]
D — impeller outer diameter [m]
u₂ — peripheral velocity at impeller tip [m/s]
hc — centrifugal pressure head equivalent [m]
Hₑ — ideal Euler head (zero pre-whirl assumption) [m]
g = 9.81 m/s²

Material Speed Limits

Material	Max u₂ (m/s)	Notes
Cast iron	~40	Low-cost; brittle at high speed
Bronze / brass	~50	Good corrosion resistance
Stainless steel	~80	Standard for water pumps
Carbon steel	~100	High-head applications
Titanium alloy	~150	Aerospace / high-performance

Tip speed u₂ is the principal design variable for centrifugal pumps and fans. The achievable head scales with u₂² — doubling tip speed quadruples the theoretical maximum head. Noise and vibration increase sharply above ~50 m/s.