Introduction
Here you find 17 WANDA cases which help to understand the waterhammer phenomena. All cases include a movie. In order to play the movie, you must install the Techsmith ScreenCapture Codec (more information - Download).
The examples are also available as Wanda cases - Download
1) Positive pressure waves
Description: Instantaneous valve closure at the end of a frictionless pipe
Phenomenon: Propagation of positive pressure wave
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction |
No friction |
Wave speed |
1000 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve
- instantaneous closure (within 1 timestep)
2) Positive and negative pressure waves
Description: Instantaneous valve closure in the middle of a frictionless pipe
Phenomenon: Propagation of positive and negative pressure wave
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
5000 m; |
Friction |
No friction |
Wave speed |
1000 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve
- instantaneous closure (within 1 timestep)
3) Pressure waves and line packing
Description: Instantaneous valve closure at the end of a pipe with friction (line packing)
Phenomenon: Propagation of positive pressure wave and line packing
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction factor |
0.0222 (k = 1 mm) |
Wave speed |
1000 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve
- instantaneous closure (within 1 timestep)
4) Effect of surge tower on pressure waves
Description: Instantaneous valve closure at the end of a pipe with friction and surge tower as the anti-surge device
Phenomenon: Effect of surge tower on pressure waves
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction factor |
0.0222 (k = 1 mm) |
Wave speed |
1000 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve
- instantaneous closure (within 1 timestep)
Surge tower:
- Area = 0.01 m 2 (vertical pipe with 113 mm internal diameter)
5) Propagation and development of negative pressure wave
Description: Pump trip with small polar moment of inertia
Phenomenon: Propagation and development of negative pressure wave
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction factor |
0.0218 (k = 0.25 mm) |
Static head |
2.0 m |
Wave speed |
1000 m/s |
Initial velocity |
0.6 m/s |
Pump data:
- Duty point is 100 m3/h at 17 m head
- Polar moment of inertia 0.1 kgm2
6) Propagation and development of negative pressure wave 2
Description: Pump trip with large polar moment of inertia
Phenomenon: Propagation and development of negative pressure wave
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction factor |
0.0218 (k = 0.25 mm) |
Static head |
2.0 m |
Wave speed |
1000 m/s |
Initial velocity |
0.6 m/s |
Pump data:
- Duty point is 100 m3/h at 17 m head
- Polar moment of inertia 2.0 kgm2
7) Effect of surge tower
Description: Pump trip with small polar moment of inertia and surge tower as the anti-surge device
Phenomenon: Effect of surge tower
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction factor |
0.0218 (k = 0.25 mm) |
Static head |
2.0 m |
Wave speed |
1000 m/s |
Initial velocity |
0.6 m/s |
Pump data:
- Duty point is 100 m3/h at 17 m head
- Polar moment of inertia 0.1 kgm2
Surge tower:
- area 0.1 m2
8) Reflections on diameter changes
Description: Two frictionless pipes in series with different diameters; instantaneous valve closure at the end of the system in the pipe with smallest diameter (reflection)
Phenomenon: Effect of diameter change on pressure wave - reflection
System data
Property |
Value |
---|---|
Diameter Pipe 1 |
500 mm |
Diameter Pipe 2 |
250 mm |
Length |
5000 m; |
Friction factor |
no friction |
Wave speed |
1000 m/s |
Initial velocity D=250 |
1.0 m/s |
Valve data:
- Butterfly valve; instantaneous closure (within 1 timestep)
9) Reflections on diameter changes 2
Description: Two frictionless pipes in series with different diameters; instantaneous valve closure at the end of the system in the pipe with largest diameter (reflection)
Phenomenon: Effect of diameter change on pressure wave - reflection
System data
Property |
Value |
---|---|
Diameter Pipe 1 |
250 mm |
Diameter Pipe 2 |
500 mm |
Length |
5000 m; |
Friction factor |
no friction |
Wave speed |
1000 m/s |
Initial velocity D=250 |
1.0 m/s |
Valve data:
- Butterfly valve; instantaneous closure (within 1 timestep)
10) Changes in wave speed
Description: Two frictionless pipes in series with different pressure wave celerity; instantaneous valve closure at the end of the system in the pipe with smallest wave celerity (reflection)
Phenomenon: Effect of wave celerity change on pressure wave (e.g. change in pipe material)
System data
Property |
Value |
---|---|
Diameter both pipes |
500 mm |
Length |
5000 m; |
Friction factor |
no friction |
Wave speed pipe 1 |
1000 m/s |
Wave speed pipe 2 |
200 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve; instantaneous closure (within 1 timestep)
11) Changes in wave speed 2
Description: Two frictionless pipes in series with different pressure wave celerity; instantaneous valve closure at the end of the system in the pipe with largest wave celerity (reflection)
Phenomenon: Effect of wave celerity change on pressure wave (e.g. change in pipe material)
System data
Property |
Value |
---|---|
Diameter both pipes |
500 mm |
Length |
5000 m; |
Friction factor |
no friction |
Wave speed pipe 1 |
200 m/s |
Wave speed pipe 2 |
1000 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve; instantaneous closure (within 1 timestep)
12) Reflections on branches and closed end
Description: Branched system with closed end; valve closure in main line
Phenomenon: Reflections on branches and closed end
System data
Property |
Value |
---|---|
Diameter pipe 1 |
500 mm |
Diameter pipe 2 |
500 mm |
Diameter pipe 3 |
250 mm |
Length Pipe 1 |
5000 m; |
Length Pipe 2 |
5000 m; |
Length Pipe 3 |
3000 m; |
Friction factor |
no friction |
Wave speed |
1000 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve; instantaneous closure (within 1 timestep)
13) Cavitation and cavitation collapse
Description: Concentrated cavity in high point after pump trip
Phenomenon: Effect of cavitation and cavity implosion on system pressures
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction factor |
0.0218 (k = 0.25 mm) |
Static Head |
2.0 m |
Wave speed |
1000 m/s |
Initial velocity |
1.0 m/s |
pipeline profile:
Pump data:
- Duty point is 100 m3/h at 17 m head
- Polar moment of inertia 0.5 kgm2
14) Cavitation and cavitation collapse 2
Description: Extended cavity in horizontal pipeline after pump trip
Phenomenon: Effect of cavity and cavity implosion on system pressures
System data
Property |
Value |
---|---|
Diameter |
250 mm |
Length |
10000 m; |
Friction factor |
0.0218 (k = 0.25 mm) |
Static Head |
2.0 m |
Wave speed |
1000 m/s |
Initial velocity |
0.6 m/s |
pipeline profile:
Pump data:
- Duty point is 100 m3/h at 17 m head
- Polar moment of inertia 0.1 kgm2
15) Propagation of pressure waves; development of flow velocity
Description: Instantaneous valve opening at the end of a pipe with friction
Phenomenon: Propagation of pressure waves; development of pipe velocity
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m; |
Friction factor |
no friction |
Wave speed |
1000 m/s |
Initial velocity |
0 m/s |
Valve data:
- Butterfly valve; instantaneous opening (within 1 timestep)
16) Rigid column method limitations
Description: Comparison of rigid column approximation and water hammer equations
Phenomenon: Maximum pressure is significantly underestimated by rigid column
approximation if friction head is small
System data
Property |
Value |
---|---|
Diameter |
200 mm |
Length |
900 m; |
Wave speed |
900 m/s |
Initial velocity |
3.0 m/s |
17) Linear and two-stage valve closure
Description: Linear and two-stage valve closure at the end of a pipe with friction
Phenomenon: Effective valve closure time
System data
Property |
Value |
---|---|
Diameter |
500 mm |
Length |
10000 m |
Friction Factor λ |
0,0154 (wall roughness k = 1 mm) |
Wave speed |
1000 m/s |
Initial velocity |
1.0 m/s |
Valve data:
- Butterfly valve; linear and two-stage valve closure in 5 pipe periods