A hydraulic ram is a pump which raises water without any external power for its operation. One essential requirement for the satisfactory operation of a hydraulic ram is the availability of a large quantity of water with a small positive head or height. This large quantity of water at a small height is sufficient to lift small quantity of water to a greater height. It works on the principle of “Water Hammer”.
Fig.: Hydraulic Ram
Efficiency of Hydraulic Ram
Let
W = weight of water flowing per second into the chamber,
w = weight of water raised per second,
h = height of water in supply tank above the chamber,
H = height of water raised from the chamber.
The energy supplied by the supply tank to the ram
= weight of water supplied × Height from which the water is supplied.
= W × h.
Energy delivered by the ram
= Weight of water raised × height through which water is raised.
= w × H.
Thus efficiency = energy delivered by the ram/ energy supplied to the ram
η = (w × H)/(W × h)
The efficiency η, specified above is called as D’ Aubusson’s efficiency.
Rankine gave another form of efficiency as he considered that the weight of water raised is not H, but it is (H-h).
Thus, Rankine efficiency η = [w × (H-h)]/[(W-w) × h].
