Processing math: 100%
Menu

Water hammer

Values for calculation

Q_{max} \mathrm{m^3/s}
D \mathrm{mm}
D_p \mathrm{mm}
L \mathrm{m}
H \mathrm{m}
g \mathrm{m/s^2}
T \mathrm{°C}
ρ \mathrm{kg/m^3}
w \mathrm{m\cdot\ s^{-1}}
E \mathrm{Pa}
ζ
c_{ef}
t \mathrm{s}
e \mathrm{mm}

Calculation

Velocity in valve

v_{max}=\cfrac{4\cdot 10^6\cdot Q_{max}}{π\cdot D^2}

Theoretical pressure in the valve at full opening

Δ_h=\cfrac{v_{max}^2}{2\cdot g}\cdot \left(ζ+1\right)

Pressure parameter

p=\cfrac{Δ_h}{H}

0 < p \le 1

Effective closing time

t_{ef}=t\cdot c_{ef}

Volume elastic modulus

K=w^2\cdot ρ

Speed pressure waves in the pipe

a=\cfrac{w}{\sqrt{1+\cfrac{D_p}{e}\cdot\cfrac{K}{E}}}

Speed in the pipe

v_p=\cfrac{4\cdot 10^6\cdot Q_{max}}{π\cdot D_p^2}

Water hammer

\text{if }\ t_{ef}\geq \cfrac{2\cdot L}{a}
ΔP=\cfrac{L\cdot v_{max}}{t_{ef}\cdot g}
\text{else}
ΔP=\cfrac{a\cdot v_{max}}{g}