Compare the pumping of water to a higher elevation to isentr

Compare the pumping of water to a higher elevation to isentropic compression of air into a compressed-air tank as means of storing energy for later use.

Solution

basic equation of hydrolic machine e.i eulers equation is independent of density. Head=V2*v2/g.this means when the pump running in air ,the head generated is in terms of meter of air.if the pump is primed with water,the head generated is same meter of water .but as the density of air is very low,the generated head of air in terms of equivalent meter of water head is negligible.this is also the main reason why we are doing priming to suck water through the pump.