Symbol

Definition

BPF

Blade passing frequency, Hz

c₁

Fluid velocity at impeller inlet, m/s

c₁^\

Fluid velocity at impeller inlet corresponds to blade shift angle, m/s

c₂

Fluid velocity at impeller outlet, m/s

c_u2

Euler component of fluid velocity at impeller outlet, m/s

c_m2

Flow component of fluid velocity at impeller outlet, m/s

c_s

Fluid velocity at the pump suction, m/s

g

Gravitational acceleration, m/s²

H

Pump total head, m

Q

Pump discharge, l/h

N

Pump rotational speed, Hz, rpm.

NPSH_A

Available net positive suction head, m

NPSH_R

Required net positive suction head, m

p_s

Absolute pressure in the pump suction, related to the pump centreline, Pa

P_s

Absolute pressure at the pump suction, bar

P_d

Absolute pressure at the pump discharge, bar

p_v

Absolute vapour pressure at the fluid temperature, Pa

RF

Frequency corresponds to the pump rotational speed = N/60, rps or Hz

u₁

Peripheral speed of impeller inlet, m/s

u₂

Peripheral speed of impeller outlet, m/s

w₁

Fluid velocity at impeller inlet relative to the impeller peripheral speed, m/s

w₂

Fluid velocity at impeller outlet relative to the impeller peripheral speed, m/s

w₁^\

Fluid velocity at impeller inlet relative to the impeller peripheral speed corresponds to blade shift angle, m/s

z

Potential elevation, m

β₁

Inlet blade angle, degree

β₁^\

Inlet blade angle at high flow rate, degree

Β₂

Outlet blade angle, degree

Δβ₁

Blade shift angle at blade entrance, degree

x

Cavitation strength, %

ρ

Density of fluid, kg/m³

s

Thoma cavitation number