Knowledge

 

Cavitation in fuel pipes

The so-called cavitation arises when in a flowing liquid the vapor pressure is locally falling short and then vapor bubbles are formed. This flow cavitation can occur inside fuel pipes at bending points in case the cross section of the pipe changes. Therefore one must make sure that the cross section doesn’t get smaller around bends of the fuel pipe.

The emerging vapor bubbles are unstable and implode when the reach areas of a higher vapour pressure. The vapor bubble doesn’t decay in a uniform manner but by forming a needle-like liquid beam which is oriented towards the pipe face and hits the surface with a velocity of up to 1 km/s. The material is initially deformed plastically then it passes a strengthening phase and finally it fatigues. Cracks are formed and a gradual destruction of the metal structure. This erosion cannot be avoided by using different materials. The proper remedy is to make sure that there are steady flow conditions inside the pipe.