Subject Applied Hydraulics

Topics : Hydraulic Accumulator

Difficulty : Medium

Cavitation is defined as the phenomenon of formation of vapour bubbles in the region of flowing liquid where its pressure falls below the vapour pressure of liquid then the liquid will vapourise and flow will no longer will be continuous

When these vapour bubbles travel into the region of higher pressure, they suddenly collapse on the metallic surfaces and the surrounding liquid rushes to fill the cavities of vapur bubbles The severe rush of liquid causes the development of extremely high pressure

prolonged Cavitation causes erosion and pitting of metals, severe vibrations and noise shows the suction side pf pump consider two pints A and B of inlet to eye of impeller and on the sump level respectively

$p_{a}$=absolute atmospheric pressure;

$p_{s}$=absolute pressure at eye of impeller

$h_{s}$= suction lift

$V_{s}$= velocity in suction pipe

$hf_{s}$=friction losses in suction

By Bernoulli theorem $\frac{Pa}{W}=\frac{Ps}{w}+(hs-\frac{V^{2}s}{2g}+hfs)$

Therefore the absolute pressure of inlet to eye of impeller falls below thatof atmospheric pressure