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Hydraulic Ram

And Transient Analysis

Presented ByArnab Das

2011CEW3394

Under GuidanceDr. Rakesh Khosa

IIT Delhi

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What is a Hydraulic Ram?

The hydraulic ram pump may be defined

as a self-acting device that uses the energy of

a large volume of water falling from a

higher location (relative to the ram) and

passing through it, to lift a small volume to a

location significantly higher than the source

of water.

It works on the principle of Water Hammer.

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How a Hydraulic Ram works?

When a flowing liquid is suddenly brought to

rest, the change in momentum of the liquid

mass causes a sudden rise in pressure. Thisrise in pressure is utilized to raise a portion

of the liquid to higher level, thus harnessing

the force of water hammer.

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Where a Hydraulic Ram works?

http://www.meribah-ram-pump.com/index1.aspx

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SCHEMATIC DIAGRAM -HYDRAULIC RAM

Fall(Drive head)

Lift(Delivery head)

Supply pipe

Drive tank

Drive pipeHydraulicRampump

Delivery pipe

Source (river, stream, spring)Service area/Storagefacility (not shown)

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A working Hydraulic Ram

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Working Sequence-1

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Working Sequence-2

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Working Sequence-3

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Working Sequence-4

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Parts of a Hydraulic Ram

Air chamber

Impulse valve

Body

Feet

Delivery pipe stub

Delivery valve

Drive pipe stub

Air snifter

Different forms, same substance

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The Waste Valve

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Characteristics of a Hydraulic Ram

Water-Lifting System

1. There is no external energy input other than theenergy of water passing through the pump.

2. Its operation will continue 24 hours a day and

seven days a week without human interventionso long as the required volume of watercontinues to flow through it

3. Water has to come from a higher location than

a ram4. Only a small portion of this water (around 25 %

or even less) is pumped up, the remainderpassing out of the ram and must be drained toa lower location

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Characteristics of a Hydraulic Ram

Water-Lifting System

5. The water can be lifted to an extent of 1:10i.e. for a head of 1m, the lift can be achievedupto 30m but with progressively lowerefficiency.

6. Due to the rams small output per minute,there is need for a storage device at thepoint of delivery to accumulate this outputon a 24-hour basis, e.g. an earthen pond forirrigation or ferrocement, metal, or plastictank for drinking water.

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History

The first self-acting ram pump was invented by the

Frenchman Joseph Michel Montgolfier in 1796 forraising water in his paper mill (Montgolfier is more

popularly known for his work in hot-air balloons).

The sons of Montgolfier obtained an English patentfor an improved version in 1816 but this wasacquired, in 1820 by Josiah Easton, a Somerset-bornengineer whose firm later installed many rams whichare still working satisfactorily.

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Ram Pumps in the 21stcentury

In recent years there has been a resurgence ofinterest in hydraulic rams, particularly in developingcountries, due to the continuing rise in fossil-fuel

prices.

In India, Vietnam, and China their governments areactive in constructing hydraulic ram systems and in

disseminating the technology to the countryside forirrigation and drinking water.

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Technical Discussions

The valve will open however light it may besince the pressure in the valve box is reducedbelow that of the atmosphere by the refluxaction of the water on its rebound.

Air is being drawn through air snifting valve

into the valve box when the pressure fallsbelow the atmosphere.

contd

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Technical Discussions

Force tending to Open the Valve=(Atm Pressure-Pressure inside Valve) + Wt ofValve

Force tending to close the Valve=(Transient Pressure Atm Pressure) Wt ofValve

- Open time will tend to increase as the Wtincreases

Contd..

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Technical Discussions

For all practical purposes, the valve openingmay be considered as Instantaneous.

Velocity of Flow in supply pipe after t secs:

Contd...

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Technical Discussions

- For efficient working, wt of the valve shouldbe such that velocity in pipe is 0.4h

dft/sec.

- The time taken by valve to close cannot becalculated accurately but increases when thelift and wt of valve increases

- Time during which valve is on its seat

increase with increase in the distancebetween delivery head and waste valve;and as delivery head increases.

Contd...

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Technical Discussions

Ram Efficiency

= qhd/ (Q+q)H

DAubuissonsFormula

= q(hd-H)/ QHRankinesFormula

Sources of Loss:

1. Leakage at waste valve

2. Resistance of valve and Pipe3. Eddy formation due to section change

4. Loss of resilient energy

Contd...

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Technical Discussions

Increasing the travel of waste valve, increases thevelocity of efflux and the time of opening andtherefore the leakage but at the same time

increases the pressure which translate into higherdelivery head. A point is reached where increasedleakage losses counter-balance the proportionalgain of energy.

The volume of Air Chamber should be approx 100times the volume of water delivered per cycle

Contd...

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Actual Performance Chart

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Efficiency Chart for Head of 4.5ft

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MY OBJECTIVE

1. Construction of a hydraulic Ram

model2. Validation of experimental data

through numerical modelling

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References:

1. Hydraulic Ram Pump System Design and Application

- Dr. Abiy Awoke Tessema, Ethiopia (ATF)

2. Hydrauli c Ram Pumps - A Guide to Ram Pumps Water Supply System

- Jeffery, T. D., Intermediate Technology Publ ications

3. Theory and Applications of H ydrams

- S. Hazarika, Technical Digest (no. 10, 2007)

4. Hyraulic Ram Pump

- Teferi Taye (Journal of ESME, Jul98, Etiopia)

5. Downstream Hydraulic Transients in combined Free Sur face and

Pressured flow in Pipes

- Nathan Faber (Thesis, Californ ia State University)

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References:

6. Design and Construction of Hydraulic Ram Pump

- Shuaibu Mohammed, Leonardo Journal (no. 11, 2007), Niger ia

7. Water Power Engineer ing

- Dnadhar, M. M . and Sharma, K.N. , Vikas Publication House

8. Hydraulic Machines

- Jagdish Lal, Dhanpat Rai and Sons Publication

9. F luid Mechanics and Hyraul ic Machines

- Bansal, R. K. , Luxmi Publications

10. Hydaul ics and its Appli cations

- Gibson, A. H ., Constable and Company Ltd. (London)

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Multiple-ram set up

Six 4-inch hydraulic rams with a combined output of more than 300,000 liters

per day irrigate around 35 hectares of farmland in central Negros Occidental.

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