Energy and power in hydraulic system

1. PRESENTATION
ON
“ENERGY AND POWER IN
HYDRAULIC SYSTEMS”
OIL HYDRAULICS AND PNEUMATICS
SUBMITTED BY:
HIMANSHI GUPTA (140120119057)/ ME/A1
GUIDED BY:
PROF. SAMIR RAVAL
(2171912)
GANDHINAGAR INSTITUTE OF TECHNOLOGY

2. INTRODUCTION
• Fluid power is the technology that deals with the generation,
control and transmission of forces and movement of
mechanical element or system with the use of pressurized
fluids in a confined system.
• Both liquids and gases are considered fluids.
• Fluid power system includes a hydraulic system and a
pneumatic system.
• Hydraulics is the study of incompressible fluids or liquids in
motion.

3. HOW FLUID POWER WORKS
• Pascal's Law expresses the central concept of fluid power.
• It states that the pressure exerted on a confined fluid is
transmitted undiminished in all directions and acts with equal
force on equal areas and at right angles to the containing
surfaces.

4. REVIEW OF MECHANICS BEHIND
FLUID POWER
• Forces are essential to the production of work.
• No motion can be generated and hence no power can be transmitted
without the application of some force.
• The three laws of motion formulated by Sir Isaac Newton dealing
with the effect a force has on a body are:
1) Every object will remain at rest or in uniform motion in a straight
line unless compelled to change its state by the action of an
external force.
2) If a body is acted upon by a force, the body will have an
acceleration proportional to the magnitude of the force and
inversely to the mass of the body.
3) For every action in nature there is an equal and opposite reaction.

5. • Velocity is defined as the distance travelled divided by the
corresponding time.
v = d/t
where
d = distance
t = time
v = velocity
• Newton's first law of motion states that a force is required to
produce this change in motion.
• As per Newton's second law, we have
F = ma
where
F = force
a = acceleration
m = mass

6. • The amount of work is equal to the product of force and distance
where both the force and distance are measured in the same
direction.
W = Fd
• Power is defined as the rate of doing work.
P = Fd/t
(or) P = Fv
where
F = force
v = velocity
P = power
• Efficiency, another significant parameter when dealing with
work and power, is defined as output power divided by input
power.

7. APPLICATIONS OF PASCAL'S LAW
• The underlying principle of the hydraulic jack and hydraulic
press.
• Force amplification in the braking system of most motor
vehicles.
• Used in artesian wells, water towers, and dams.
• Scuba divers must understand this principle. At a depth of 10
meters under water, pressure is twice the atmospheric pressure
at sea level, and increases by about 100 kPa for each increase
of 10 m depth.

8. APPLICATIONS OF PASCAL'S LAW
HYDRAULIC BRAKE HYDRAULIC PRESS

9. CONSERVATION OF ENERGY
• The first law of thermodynamics states that energy can
neither be created nor be destroyed.
• Moreover, all forms of energy are equivalent.
• The total energy present in the fluid flow includes potential
energy due to elevation and pressure and also kinetic
energy due to velocity.

10. APPLICATION OF LAW OF
CONSERVATION OF ENERGY
• If you shoot the cue ball at a
stationary balls across the table, the
cue ball has Kinetic Energy, where
as, the other balls only have
potential energy.
• When the cue ball collides with the
other balls, the kinetic energy will
transfer from the cue ball to all the
other balls, sending the balls in
motion.
• Now that the other balls is in
motion they have Kinetic energy.
• This clearly represents the law of
conversation of energy.

11. CONTINUITY EQUATION
• For any control volume the principle
of conservation of mass says:
Mass entering per unit time =
Mass leaving per unit time +
Increase of mass in the control volume
per unit time
• For steady flow there is no increase in
the mass within the control volume, so
for steady flow
Mass entering per unit time =
Mass leaving per unit time

12. APPLICATIONS OF EQUATION
OF CONTINUITY
• Common applications where the equation of
continuity is used are:
• Pipes, tubes and ducts with flowing fluids or gases
• Rivers
• Overall processes as power plants
• Diaries
• Logistics in general
• Roads
• Computer networks
• Semiconductor technology

13. HYDRAULIC HORSEPOWER
• Hydraulic horsepower can represent the power available
within hydraulic machinery, or can be used to estimate the
mechanical power needed to generate a known hydraulic
flow rate.
• It may be calculated as

14. BERNOULLI'S EQUATION
• Bernoulli's principle states that an increase in the speed of a fluid
occurs simultaneously with a decrease in pressure or a decrease in
the fluid's potential energy.
• Bernoulli's principle can be derived from the principle
of conservation of energy.
• This states that, in a steady flow, the sum of all forms of energy in
a fluid along a streamline is the same at all points on that
streamline.
• This requires that the sum of kinetic energy, potential energy
and internal energy remains constant.
• Thus an increase in the speed of the fluid – implying an increase in
both its dynamic pressure and kinetic energy – occurs with a
simultaneous decrease in (the sum of) its static pressure, potential
energy and internal energy.

16. APPLICATION OF BERNOULLI'S
PRINCIPLE: AIR FLIGHT
• The main way that Bernoulli's principle works in air flight has to do
with the architecture of the wings of the plane.
• In an airplane wing, the top of the wing is some what curved, while the
bottom of the wing is totally flat.
• While in the sky, air travels across both the top and the bottom
concurrently.
• Because both the top part and the bottom part of the plane are designed
differently, this allows for the air on the bottom to move slower, which
creates more pressure on the bottom, and allows for the air on the top to
move faster, which creates less pressure.
• This is what creates lift, which allows planes to fly.
• An airplane is also acted upon by a pull of gravity in which opposes the
lift, drag and thrust.
• Thrust is the force that enables the airplane to move forward while drag
is air resistance that opposes the thrust force.

18. APPLICATION OF BERNOULLI'S
PRINCIPLE: PUMPS
• Volute in the casing of
centrifugal pumps
converts velocity of fluid
into pressure energy by
increasing area of flow.
• The conversion of kinetic
energy into pressure is
according to the Bernoulli
equation.

19. • pin / ρ + vin
2 / 2 + g hin + wshaft =
pout / ρ + vout
2 / 2 + g hout + wloss
where
• p = static pressure (Pa)
• ρ = density (kg/m3)
• v = flow velocity (m/s)
• g = acceleration of gravity
(9.81m/s2)
• h = elevation height (m)
• wshaft = net shaft energy per unit
mass for a pump, fan or similar
(J/kg)
• wloss = loss due to friction (J/kg)

20. • Ejectors are designed to convert the pressure energy of a
motivating fluid to velocity energy to entrain suction fluid
and then to recompress the mixed fluids by converting
velocity energy back into pressure energy. Ejectors are
composed of three basic parts: a nozzle, a mixing
chamber and a diffuser.
APPLICATION OF BERNOULLI'S
PRINCIPLE: EJECTORS

21. TORICELLI'S THEOREM
• Torricelli's theorem relates the speed
of fluid flowing out of an orifice to
the height of fluid above the opening.
• The law states that the speed of
efflux, v, of a fluid through a sharp-
edged hole at the bottom of a tank
filled to a depth h is the same as the
speed that a body would acquire in
falling freely from a height h.
• The expression can be obtained by
equating the kinetic energy gained
with the potential energy lost, mgh ,
and solving for v:

22. SIPHON
• A siphon is a hydraulic device.
• It is commonly used to cause a
liquid to flow from one
container in an upward
direction over an obstacle to a
second lower container in a
downward direction.
• A siphon consists of a U-tube
with one end submerged below
the level of the liquid surface,
and the free end lying below it
on the outside of the container.

23. THANK YOU