Water hammer simulation in hydraulic piping systems
Pressure surges – also known as water hammer or pressure shock – occur in piping systems when the flow rate changes abruptly, such as when valves close rapidly or pumps suddenly shut down. These extreme pressure spikes can lead to material fatigue, component failure, or leaks, posing a significant risk to system reliability and safety.
Common Applications for Pressure Surge Simulation:
- Water supply systems: Preventing pipe bursts caused by sudden pressure increases.
- Industrial and chemical plants: Protecting pipelines from damage due to rapid valve movements.
- Hydraulic systems: Optimizing piping networks to reduce pressure fluctuations and cavitation effects.
With the Piping Systems Library in DSHplus, pressure surges can be accurately simulated, allowing engineers to identify critical pressure peaks early and develop effective protective measures. This enables targeted optimization and safer system design.
The following video demonstrates pressure surge simulation with DSHplus, using the example of a constantly flowing pipeline, where a safety valve is abruptly closed.
Effects of Pressure Surges on Piping Systems
Dynamic pressure spikes can cause severe damage, ranging from burst pipes and broken supports to damaged valves, pumps, and heat exchangers.
Pressure Surges: More Than Just an Issue in Inlet Pipelines
Pressure surges are often associated only with inlet pipelines, but many critical pressure shocks actually occur on the outlet side of a system. While the inlet side experiences a sudden pressure rise, the outlet side typically goes through a brief phase of very low pressure before the actual surge occurs. This temporary pressure drop results from the dissipation of the kinetic energy of the moving fluid column, a phenomenon particularly relevant in hydraulic and water-based systems.
Cavitation and the Importance of Fluid Composition
The pressure conditions during deceleration are influenced not only by flow velocity, braking pressure, and valve closing time but also by the physical properties of the fluid. The air content in the liquid plays a crucial role:
- In mineral oil-based fluids (e.g., HLP), a cavitation-like zone can form.
- In water-based fluids (e.g., HFC), true cavitation occurs, leading to the formation and collapse of vapor bubbles.
Realistic Pressure Surge Simulation with the Piping Systems Library
For an accurate pressure surge simulation, the pipe model must capture not only the actual surge but also the preceding dynamic effects, including cavitation and cavitation-like conditions in the tank line.
Additional information can be found in the O+P publication "Dieselgate im Tankrohr".