Water Hammer

Purpose

Approximate solution to water hammer problems

• Pressure wave
• Head
• Wave reflection time
• Sudden valve closure
• Slow valve closure

Overview

Methodology

Wave Speed
$U=\sqrt{\frac{E}{\mathrm{\rho \; <!--\; greek\; small\; letter\; rho\; -->}}}\sqrt{\frac{1}{1+\frac{DE}{t{E}_p}}}$

Pressure head due to sudden valve closure
$\mathrm{\Delta \; <!--\; greek\; capital\; letter\; delta\; -->}{h}_{\mathrm{sudden}}=\frac{-U\mathrm{\Delta \; <!--\; greek\; capital\; letter\; delta\; -->}V}{g}$

Approximate head due to gradual valve closure
$\mathrm{\Delta \; <!--\; greek\; capital\; letter\; delta\; -->}{h}_{\mathrm{gradual}}=\frac{t_i\mathrm{\Delta \; <!--\; greek\; capital\; letter\; delta\; -->}h}{T}=\frac{2L\mathrm{\Delta \; <!--\; greek\; capital\; letter\; delta\; -->}V}{gT}$

Hoop stress
$\mathrm{\sigma \; <!--\; greek\; small\; letter\; sigma\; -->}=\frac{pD}{2t}$

Options

• Input parameters are in Blue
• Outputs are in dark brown

Glossary

none

Example Data

References

Resources

1. AFT Webinar
2. Crowley
3. Grady, Practical Engineering
4. BLACOH
5. Rouse

Limitations

Use at your own risk

2017 B. SHRESTHA