8/3/2019 HFD 007

1/18

Delivered To

Batch# ND 07

Date: 01.11.2011

8/3/2019 HFD 007

2/18

8/3/2019 HFD 007

3/18

Hydraulicsy Hydraulics has been derived from Hudour which

means WATER.

y It is the science which deals with water, at rest and atmotion.

y Fluid Mechanics is that branch of EngineeringScience which deals with the behavior of fluid underthe conditions at rest & motion.

8/3/2019 HFD 007

4/18

Important Termsy Density: It is Mass per Unit Volume at NTP.

y Specific Weight(WeightDensity): It is Weight per

Unit Volume at NTP.

y Specific Volume: It is the Volume per Unit Mass ofLiquid.

y Specific Gravity: It is the ratio of Specific Weight of aLiquid to the Specific Weight of pure Water at 4rC.

8/3/2019 HFD 007

5/18

Properties ofLiquidy Viscosity: It is the property of fluid which offer resistance to the

movement of one layer of f luid to another adjacent layer.

y Kinematic Viscosity: It is the ratio of dynamic viscosity to the density

of liquid.

y Compressibility: It is the virtue of fluid for which liquids undergo achange in volume with change in pressure.

y Surface Tension: It is the property of fluid which enables it to resisttensile stress.

y Capillarity: It is the phenomena of rise or fall of liquid surface in a

vertical tube held in a liquid relative to general level of the liquid.

8/3/2019 HFD 007

6/18

Pressure ofa Liquid

When a liquid is contained in a vessel, it exerts force atall points on the sides and bottom of the vessel.

Force per unit area is called Intensity of Pressure.

p=P/A

Intensity of Pressure at any point

=Weight Density X Vertical Height

8/3/2019 HFD 007

7/18

Pascals Law

yAccording to Pascals Law:

The intensity of pressure at any point in a fluid at rest

is same in all direction.In other words, when a certain pressure is applied atany point in a fluid at rest, the pressure is equallytransmitted in all the directions and to every other

point in fluid.

8/3/2019 HFD 007

8/18

Pressure Typesy Atmospheric Pressure: It is the normal pressure which the atmospheric

air exerts upon all surface in contact.

At sea level,itsvalue is 101.325 KPa or 760 mm Hg Pressure

y Gauge Pressure: The pressure measured with the help of pressure gauge,taking atmospheric pressure as datum, is known as gauge pressure.

y Absolute Pressure: It is pressure actually exerted. All the pressure gaugesshows the difference between the actual and atm. pressure.It is called

absolutepressure.

y Vacuum Pressure: It is the pressure of a liquid which is below theatmospheric pressure.

8/3/2019 HFD 007

9/18

Relationship between Pressures

8/3/2019 HFD 007

10/18

Pressure Measuring Equipments

y Two main types:

1. Manometers: Works on balancing column of liq.

2. Mechanical Gauges: Works on deflection of appliedpressure & this movement mechanically magnified

1. Manometers:

a) Simple: Piezometer, U-tube & Single Column.

b) Differential: 2-Piezometer, Inverted u-tube,U-tube Differential & Micromanometer.

2. Mechanical Gauges: Bourdon Tube, Diaphragm, Bellowsand Dead-Weight Pressure Gauge

8/3/2019 HFD 007

11/18

Lock Gatesy Lock Gates: Lock gates are provided in navigation

chambers to change the water level in a canal or

river for navigation.In Lock Gates,the reaction between two gates is:

R=P/2sin

8/3/2019 HFD 007

12/18

Buoyancy

y Archimedes Principle: When a body is immersed,wholly or partially in a liquid, it is lifted up by a force

equ

al to the weight of liqu

id displaced by the body.

y Buoyancy: The tendency of liquid to uplift animmersed body, because of upward thrust of the

liqu

id, is known as bu

oyancy. The force tending to liftup the body is called the Buoyant Force.

The point through which buoyant force is supposedto act, is known as Centre of Buoyancy.

8/3/2019 HFD 007

13/18

EquilibriumofFloating BodyThree types.

1. Stable: If a small angular displacement of the body sets up acouple that tends to oppose the angular displacement of the

body, tending to bring it back to its original position.

2. Unstable: Ifa small angular displacement ofthe body sets upa couple that tends to further increase the angular displacementof the body, resisting the tendency to restore its originalposition.

3. Neutral: If a small angular displacement of the body doesntset up any couple of any kind, and therefore the body adoptsthe new position given to it by the angular displacement,without tending to bring it back to its original position neitherresisting the tendency to restore its original position.

8/3/2019 HFD 007

14/18

Metacentre and Metacentric Height

y Metacentre: It is the point about which a floatingbody starts to oscillate, when given a small angulardisplacement.

y Metacentric Height: It is the distance between thecentre of Gravity & the Metacentre.

Mathematically,

Metacentric Height,

GM=(I/V)-BG=BM-BG

8/3/2019 HFD 007

15/18

Types ofFlowsy Uniform Flow

y Non-Uniform Flow

y Streamline Flow

y Turbulent Flowy Steady Flow

y Unsteady Flow

y Compressible Flow

y Incompressible Flowy Rotational Flow

y Irrotational Flow

y 1-D,2-D & 3-D Flow

8/3/2019 HFD 007

16/18

Types ofEnergies or Head ofLiquid in Motion

y Potential Energy/Potential Head(z): It is due to the position

above some suitable datum line

y Kinetic Energy/Kinetic Head: It is due to velocity offluid.

y Pressure Energy/Pressure Head: It is due to the pressure of

liquid.

8/3/2019 HFD 007

17/18

Important Equations

y Bernoullis Equation: For a perfect incompressible fluid, flowing in acontinuous stream, the total energy ofa particle remains same, while

the particle moves fromone point to another.

z1 + v12/2g + p1/w= z2 + v2

2/2g + p2/w=Constant

y Eulers / Energy Equation:

The equation is: dp/ + g.dx + v.dv=0

y Momentum Equation:

The equation is: F= d(mv)/dt

8/3/2019 HFD 007

18/18