The manner in which the collaspe of a vapour bubble causes savitation
damage has beeen investigated. it has been found that the sphere
implodes in a way similar to poking a balloon with one's finger. The
point of collapse (at the finger tip) fires a high velocity narrow
jet of water across the bubble. If the bubble is alongside the metal
surface this high speed jet causes corrosion by impact. Much the same
as high pressure water jets are used for cutting metals.
It has nothing to do with concentric reducers.
Geoff
- In PipingDesign@yahoogroups.com, Christopher Wright <chrisw@...>
wrote:
>
>
> On Feb 19, 2007, at 12:44 AM, waqas_314 wrote:
>
> > i had heard somewhere that if we place an Concentric reducer at
the
> > inlet(suction) of a pump then there will be cavitation
action.because
> > there will be AIR POCKETS produce.
> cavitation occurs in liquids when the local pressure drops below
the
> vapor pressure of the fluid and small bubbles form. These aren't
air
> pockets--they're vapor. At some point the pressure increases and
the
> bubbles collapse suddenly causing impacts which damage the metal
> surface.
> It's possible to get cavitation in a reducer under the right
physical
> conditions, but cavitation is usually associated with high velocity
and
> sudden changes on flow area leading to pressure drops.
>
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw@... | this distance" (last words of Gen.
> .......................................| John Sedgwick,
Spotsylvania
> 1864)
> <a href="http://www.skypoint.com/~chrisw/">http://www.skypoint.com/~chrisw/</a>
>
Received on Tue Feb 20 16:58:00 2007