Fluid Mechanics Solutions

Pressure surges in pipeline systems resulting from air releases.

 

The final release of air through air valves produces a pressure surge. This phenomenon, which results from the rapid deceleration of liquid at the instant the air is is fully expelled , is called "airslam". It produces a pressure surge similar to to the one produced by the rapid liquid decelaration that results form a valve closure. If the air is released too rapidly, an excessive pressur surge can occur.It is important to design the air releae valves to avoid excessive pressure surges.

A transient flow model was set up to produce an air slam at an air valve. The heads on the left of the valve is lowered from 30 m to 6 m in 10 sec then raised back up to 30 m in the next 10 sec. An air valve with a 200 mm inlet and outlet orifice was analyzed.

 

 

 

 

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