# 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 ( |

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 ( |

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 ( |

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 kgm
^{2}

# 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 ( |

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 kgm
^{2}

# 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 ( |

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 kgm
^{2}

**Surge tower:**

- area 0.1 m
^{2}

# 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 ( |

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 kgm
^{2}

# 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 ( |

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 kgm
^{2}

# 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