hydraulics objectives.xlsx

8/14/2019 hydraulics objectives.xlsx

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Osborne Reynold he makes possible to predict the characteristics of flow of any fluid

path line / streamlines path followed by a particle

imaginary curves drawn through a fluid to indicate direction of motion of

flow

stream tube small bundle of path lines

represents elementary portion of a flowing fluid bounded by a group of

stream lines w/c confines flow

Discharge or flow rate is the amount of fluid passing through a section per unit of time

steady flow discharge is constant with time

uniform flow average velocity is the same

usually occurs when an incompressible fluid flows through a stream with

uniform cross section

non-uniform flow velocity changes

continuous flow discharge at every section is the same

laminar flow path of individual fluid particles do not intersect or cross

turbulent flow path of individual particles are irregular and continuously cross each other

one-dimensional flow occurs when in an incompressible fluid, the direction and magnitude of

velocity at all points are the same

two-dimensional flow occurs when fluid particles move in plane or parallel planes and streamline

patterns are the same

flow nets indicate flow patterns in case of two-dimensional flow

kinetic

potential

kinetic energy ability of fluid mass to do work

elevation energy energy possesed by fluid by virtue of its position or elevation with respect

to a datum plane

potential energy also know as pressure energy

total head or energy is the sum of kinetic and potential energy

power is the rate at which work is done

bernoulli's energy theorem results from application of principles of conservation of energy

ideal or theoretical values values that we get from neglecting head loss

actual values values that we get from considering head loss

pump is used to increase head

hydraulic grade line is the graph representation of total potential energy of flow

energy grade line is the graph representation of total energy of flow

Orifice An opening with a closed perimeter through which a fluid flows.Measurement or control of

flow

Purpose of an orifice.

Tube An orifice with prolonged sides.

Sharp-edged circular

orifice

Most common cross-section for fluid measurement.

Mean velocity Velocity due to the mean head.

Velocity of approach Mean velocity in the channel of approach

CHAPTER 5

energy possesed by flowing fluid consists of __ and __ energy

CHAPTER 6


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Torricellis theorem The theoretical velocity of discharge from an orifice is therefore the

velocity acquired by a body falling freely in a vacuum through a height

equal to the head on the orifice.

Coefficient of velocity, Cv Ratio of actual mean velocity, V to the theoretical velocity, Vt.

Contraction of the jet Phenomenon in which the fluid particles follow a curvilinear path, thus

causing the jet to contract for a short distance beyond the orifice.

Vena contracta Section where contraction caused by the orifice ceases.

D Distance of vena contracta for a sharp-edge circular orifice.

Coefficient of contraction,

Cc

Ratio of cross-sectional area of the jet at the vena contracta to the area of

the orifice.

Coefficient of discharge, C Product of Ccand Cv

Inversion of the jet Change of cross-section of the jet as it reaches the vena contracta.

Pitot tube Used to measure the velocity in the jet with fair accuracy.

Coordinate method Method used to determine the velocity of the jet.

Medaugh and Johnson Made an experiment to determine the coefficients of discharge of sharp-

edged circular orifices.

Schoder and Dawson Stated that the percent increase in Q due to rounding equals 3.1 times the

percent that r is of D.

Gate Opening in a dam or other hydraulic structure to control the passage of

water.

Suppressed contraction If a gate has any portion of its edge flushes with the bottom or a side of the

channel of approach.

Sluice gate A gate which has its lower edge in or near the bed of a channel.

0.82H Pressure head at the contracted section of the tube.

Nozzle Converging tube.

Venturi and Eytelwein Experimented on diverging tubes.

Re-entrant or inward-

projecting tubes

Tubes having their end projecting into a reservoir.

Bordas mouthpiece A special case of the re-entrant tube, consisting of a thin tube projecting

into the reservoir about one diameter.

Pressure-momentum

theory

Based on principle of mechanics that force equals the rate of change of

momentum.

Cavitation Causes pitting of the concrete on siphon spillways.

Weir An overflow structure built across an open channel for the purpose of

measuring the flow.

Triangular weir Best adapted for measurement of other liquids.

Crest Edge or top surface with which the flowing liquid comes in contact.

Sharp-crested

Broad-crested

Free flow If the water surface downstream from the weir is lower than the crest

Actual velocity < theoretical velocity because of frictional resistance.

C decreases as the head and the size of orifice increase.

Forms of crest


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Submerged If downstream surface is higher than the crest.

Nappe Overfalling stream

Crest contraction The nappe is contracted at its under side by the action of the vertical

components of velocity just upstream from the weir.

Contracted weir If the sides of the opening also have sharp upstream edges so that the

nappe is contracted in width

Suppressed weir If the nappe suffers no contraction in width.

Full width weir Other name for suppressed

Drop-down curve Downward curvature of the surface of the liquid

Stilling well Used to measure head on weirs

Hook gage Consists of a graduated metallic rod with a pointed hook at the bottom

Point gage Like a hook gage

Law of inertia A body at rest will remain to be at rest or in motion will remain in motion

with a uniform velocity along a straight line until acted upon by an external

force.

Law of force A particle acted upon by an unbalanced force system has an acceleration in

line with and directly proportional to the resultant of the force system and

inversely proportional to its mass.

Law of stress In every action there is always an equal and opposite reaction.

Newton's third law of

motion

The force exerted by the fluid to the plate is equal but opposite in

direction.

Drag It is component of the resultant force exerted by a fluid on a body parallel

to the relative motion of the fluid.

Pressure Drag It is the resultant of all the pressure forces exerted on the surface of the

body.

Friction Drag It is the resultant of the shear stress along the surface of the body in the

direction of motion.Lift It is the component of the resultant force exerted by a fluid on a body

perpendicular to the relative motion of the fluid.

Terminal velocity If the body falls freely for a sufficient length of time, its velocity increases

so the drag force is increased until the total upward force equals the

weight of the body and the body has acquired a constant velocity called the

______________.

Water Hammer It is a term used to express the resulting shock (pressure rise) in a pipeline

cause by the sudden decrease or stoppage of motion of the fluid.

CHAPTER 9

CHAPTER 3 - OBJECTIVES

1. Hydrostatic pressureis the pressure exerted by a fluid at equilibrium due to the force of gravity.

2. Semi graphic Methods may be used in locating the center of pressure on any plane area whosehorizontal dimension does not vary with the depth

3. Dams are built for the purpose of impounding water.


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Hydraulics Branch of science which treats of water or other fluid in motion.

Hydrostatics Study of the pressure exerted by fluids at rest.

Hydrodynamics Study of the forces exerted by or upon fluids in motion.

FluidsSubstances capable of flowing, having particles which easily move and

change their position without a separation of the mass.

Shearing StressThe amount of unit deformation up to a certain point being proportional to

the unit stress.

Unit Weight The weight of a unit volume of a fluid.

Mass Density The mass per unit volume.

Specific GravityThe ratio of the unit weight of a fluid to the unit weight of water at 4

degrees Celsius (39.2 degrees Fahrenheit).

ViscosityProperty of a fluid which determines the amount of its resistance to a

shearing stress.

Dynamic/Absolute

Viscosity

The force required to move a flat surface of unit area at unit relative

velocity parallel to another surface at unit distance away, the space

between the surfaces being filed with the fluid.

Poise Unit of viscosity

Relative ViscosityThe ratio of the dynamic viscosity of any fluid to the dynamic viscosity of

water at 68 degrees Fahrenheit.

1 Centipoise Dynamic viscosity of water at 68 degrees Fahrenheit (20 degrees Celsius)

Kinematic Viscosity The ratio of the dynamic viscosity of a fluid to its mass density.

Stoke Unit of the answer in no. 14.

Viscometer/Viscosimeter Instrument used to measure viscosity of fluids.

4. The Dam is subject to Hydrostatic Forces which tend to : (1) slide it horizontally on itsfoundation, (2) overturn it about its downstream edge or toe. These tendencies are resistedby: (1)

friction on the base of the dam, (2) gravitational forces which produce moment opposite in

direction to the overturning moment.

Chapter 1 - Fundamental Properties of Fluids

Chapter 2 - Principles of Hydrostatic Pressure

5. Hydrostatic Uplift. The hydrostatic force of water exerted on or underneath a structure tending tocause a displacement of the structure. It (1) reduces stability against sliding, (2) reduces thestability against overturning; and (3) it may increase the intensity of this pressure at the toe.

6. Buoyant Force. The force exerted vertically upward by a fluid on a body wholly or partly immersedin it; its magnitude is equal to the weight of the fluid displaced by the body.

7. Principle of Archimedes. Any body immersed in a fluid is subjected to a buoyant force equal to theweight of the fluid displaced.

8. Metacentric Height. A measurement of the initial static stability of a floating body. It is calculated as

Righting Moment. The torque which tends to restore a vessel heeled over to its upright position; it is theproduct of the righting arm and the weight of the vessel.


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Principle of Hydrostatic

Pressure

The resultant pressure on any plane in a fluid at rest is normal to that

plane.

Unit Pressure The amount of pressure per unit area.

Pascal's Law At any point in a fluid at rest, the pressure is the same in all directions.

Free Surface A liquid in which the surface is subjected to zero pressure.

VacuumAssociated with space subjected to pressure less than the prevailng

atmospheric pressure.

Perfect Vacuum A space in which is no matter either in the solid, liquid, or gaseous form.

Absolute Pressure The intensity of pressure measured above absolute zero.

Gage Pressure Measured pressure.

Pressure HeadThe height of a column of homogenous fluid of unit weight that will

produce an intensity of pressure.

Barometer A device for measuring intensities of pressure exerted by the atmosphere.

Torricelli

He discovered that, if a tube more than 30 in. long and closed at one end is

filled with mercury and then made to stand vertically with the open end

submerged in a vessel of mercury , the column in the tube will stand

approximately 30 in. above the surface of the mercury.

Mercury Barometer Name for the device discovered in no.27.

Pascal

He proved that the height of the column of mercury depended upon

atmospheric pressure,when he carried a barometer at higher elevation,

height of column decreased as altitude increased.

ManometerA tube, usually bent in the form of a U, containing a liquid of known specific

gravity, the surface of which moves proportionally to changes of pressure.

Open Type ManometerA type of manometer with an atmospheric surface in one leg and capable

of neasuring gage pressures.

Differential Type

Manometer

A type of manometer without an atmospheric surface and capable of

neasuring only differences of pressure.

PiezometerThe simplests form of manometer which is a tube tapped into the wall of a

container or conduit for the purpose of measuring the pressure.

Piezometer

Single-Tube Manometer

U-Tube Manometer

Hydrokinetics Deals with liquids that are in motion with respect both to the earth and thecontainers.

Relative EquilibriumThe liquid is in equilibrium and at rest with respect to the vessel, but it is

neither in equilibrium nor at rest with respect to the earth.

Three types of open type manometer

Chapter 4 - Relative Equilibrium of Liquids

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