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

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System data

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

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System data

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

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System data

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

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System data

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

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System data

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

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System data

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

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System data

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

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System data

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

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System data

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)

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System data

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)

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System data

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

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System data

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

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System data

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

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System data

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

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System data

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

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

Valve data:

• Butterfly valve; linear and two-stage valve closure in 5 pipe periods