2. INTRODUCTION
What is hydraulic ram ?
A hydraulic ram is a device which raises small
quantity of water without any external power
to higher level from large quantity of water
available at lower level. It works on the
principal of water hammer or inertia force of
water in a pipe line.
3.
4. WORKING
Hydraulic ram works on the principal of water hammer as
when a flowing water is suddenly brought to rest the change
in momentum of water masses causes a sudden rise in
pressure.
This rise in pressure is utilizes to raise a small quantity of
water to higher level. Initially, the waste valve is open and
delivery valve is closed. The water from supply tank start to
flow under the force of gravity and picks up speed and
kinetic energy until it forces the waste valve closed.
The momentum of the water flow in supply pipe against
now closed waste valve causes a water hammer that raises
the pressure in chamber. The high pressure of water opens
the delivery valve and water enters into the air vessel which
further compresses the air already present in the air vessel.
5. The pressure in the air vessel raises which closes the
delivery valve ,now water from air vessel is forced to flow
through delivery pipe.
Under this condition waste valve and delivery valve both
remains closed • Slowly pressure in the valve chamber falls
and waste valve again opens allowing the water to flow
through it.
Now, under this condition, flow through the supply pipe
begins again producing water hammer in the valve chamber.
The cycle is repeated.
6. EFFICIENCY
Hydraulic ram has two types of efficiencies namely D’ Aubuisson’s
efficiency and Rankine’s efficiency.
1. D’ Aubuisson’s efficiency:
Let, Q = discharge from supply tank to valve chamber
q = discharge from valve chamber to delivery tank
H = height of water in delivery tank raised above the chamber.
h = height of water in the supply tank above chamber (supply
head)
since,
Energy supplied from the supply tank = weight of water supplied
per second to chamber × height of fall or rise.
So, energy supplied from the supply tank = ρQg.h = Wxh
Energy delivered to delivery tank= ρqg.H = wxH
Efficiency of ram,
Energy delivered/Energy supplied= ρ𝑞gH/ ρQgh
η = 𝒒𝑯
Qh
7. 2. Rankine’ s efficiency:
If the water level in the supply tank is taken as datum. Then
the actual height raised is (H-h).
Energy supplied to supply tank = ρ(Q-q)gh = (W-w)h
Energy delivered to the delivery tank = ρqg(H-h) = w(H-h)
Efficiency,
η= wq(H−h)
W(Q−q)h
η= 𝐪 (𝑯−𝒉)
(𝑸−𝒒) 𝒉
This is known as Rankine’s efficiency and its value is always
less than D’ Aubuisson’s efficiency.
