In the event of a leak in a pipe element, a valve must open as soon as the pressure falls below a predefined level. This causes air to flow through the valve,which is intended to prevent the pipework from imploding. This raises the question of whether the valve is sufficiently large and how quickly it opens.

Therefore,the valve lift as a function of time was computed based on the pressure before and after the valve, the spring force and the friction losses. A constant volumetric outflow rate of air was assumed to model the real case. Furthermore,constant ambient pressure and temperature conditions have been assumed at thei nlet of the pipe.

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Thefollowing picture shows the CAD and the CFD model of the valve.

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The pictureb elow shows the resulting valve lift as a function of time. It can be seen that the valve opens fast almost up to the designed maximum valve lift, followed by a decreasing valve lift due to the inflowing air and opens again up to the maximum valve lift.

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The following video shows the pressure, the velocity magnitude and the temperature during the inflow process simultaneously.

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