the section of the shaft

8/2/2019 The Section of the Shaft

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The section of the shaft where angular displacement is zero is known as node.

Hydrostatic test for boiler consists of filling the Boiler with water and pressurizing

the water to at least one and half times the maximum operating pressure for a

short time. Every part is subject to more than the maximum stress it will normally

encounter. This is an endurance test; any weak link fails during the test.

The car radiator shown is a crossflow heat exchanger, because the liquid is flowing

vertically inside tubes and the air is flowing horizontally through the spaces

between the finned tubes. Also, by the way, it is a finned tube heat exchanger

because of the use of finned tubes in its construction.

In machining, boring is the process of enlarging a hole that has already been

drilled (or cast), by means of a single-point cutting tool , for example as in boring

a cannon barrel. Boring is used to achieve greater accuracy of the diameter of a

hole, and can be used to cut a tapered hole. Boring can be viewed as the internal-

diameter counterpart to turning, which cuts external diameters.

the thickness of this boundary layer as the distance from the wall to the point

where the velocity is 99% of the "free stream" velocity, the velocity in the middleof the pipe or river.

In 1757, mathematicianLeonhard Euler derived a formula that gives the maximum

axial load that a long, slender, ideal column can carry without buckling. An ideal

column is one that is perfectly straight, homogeneous, and free from initial stress.

The maximum load, sometimes called the critical load, causes the column to be in

a state of unstable equilibrium; that is, the introduction of the slightest lateral

force will cause the column to fail by buckling. The formula derived by Euler forcolumns with no consideration for lateral forces is given below. However, if lateral

forces are taken into consideration the value of critical load remains approximately

the same.

where

= maximum or critical force (vertical load on column),


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=modulus of elasticity,

=area moment of inert ia,

= unsupported length of column,

= column effective length factor, whose value depends on the conditions of end

support of the column, as follows.

For both ends pinned (hinged, free to rotate), = 1.0.

For both ends fixed, = 0.50.

For one end fixed and the other end pinned, = 0.699....

For one end fixed and the other end free to move laterally, = 2.0.

is the effective length of the column.

Examination of this formula reveals the following interesting facts withregard to the load-bearing ability of slender columns.

1. Elasticity and not compressive strength of the materials of the columndetermines the critical load.

2. The critical load is directly proportional to the second moment ofarea of the cross section.

3. The boundary conditions have a considerable effect on the critical loadof slender columns. The boundary conditions determine the mode ofbending and the distance between inflection points on the deflectedcolumn. The closer together the inflection points are, the higher theresulting capacity of the column.

The Rankine Gordon formula is also based on experimental results and suggeststhat a strut will buckle at a load Fmax given by:

where Fe is the Euler maximum load and Fc is the maximum compressive load. This

formula typically produces a conservative estimate of Fmax.


3/27

Carnot's theorem is a formal statement of this fact: No engine operating between

two heat reservoirs can be more efficient than a Carnot engine operating between

the same reservoirs.

This maximum efficiency is defined to be:

where

is the work done by the system (energy exiting the system as work),

is the heat put into the system (heat energy entering the system),

is theabsolute temperatureof the cold reservoir, and

is theabsolute temperatureof the hot reservoir.

A corollary to Carnot's theorem states that: All reversible engines operat ing

between the same heat reservoirs are equally efficient.

The Coefficient of Performance (COP) of the heat engine is the reciprocal of its

efficiency.

Centrifugal compressors are also similar to centrifugal pumps[1] of the style shown

in Figure 2.4. The key difference between such compressors and pumps is that the

compressor working fluid is a gas (compressible) and the pump working fluid is

liquid (incompressible). Again, the engineering methods used to design a

centrifugal pump are the same as those to design a centrifugal compressor. Yet,

there is one important difference: the need to deal with cavitation in pumps.

A clutch is a mechanical device that provides for the transmission of power (and

therefore usually motion) from one component (the driving member) to another

(the driven member). The opposite component of the clutch is the brake.

A primitive way to implement cruise control is simply to lock the throttle position

when the driver engages cruise control. However, if the cruise control is engaged

on a stretch of flat road, then the car will travel slower going uphill and faster

when going downhill. This type of controller is called an open-loop

controllerbecause no measurement of the system output (the car's speed) is used


4/27

to alter the control (the throttle position.) As a result, the controller can not

compensate for changes acting on the car, like a change in the slope of the road.

In a closed-loop control system, a sensor monitors the system output (the car's

speed) and feeds the data to a controller which adjusts the control (the throttleposition) as necessary to maintain the desired system output (match the car's

speed to the reference speed.) Now when the car goes uphill the decrease in

speed is measured, and the throttle position changed to increase engine power,

speeding the vehicle. Feedback from measuring the car's speed has allowed the

controller to dynamically compensate for changes to the car's speed. It is from this

feedback that the paradigm of the control looparises: the control affects the

system output, which in turn is measured and looped back to alter the control.

Natural convection

Main article:Natural convection

Natural convection, or free convection, occurs due to temperaturedifferences which affect the density, and thus relative buoyancy, of the fluid.Heavier (more dense) components will fall, while lighter (less dense)components rise, leading to bulk fluid movement. Natural convection canonly occur, therefore, in a gravitational field. A common example of natural

convection is the rise of smoke from a fire. it can be seen in a pot of boilingwater in which the hot and less-dense water on the bottom layer movesupwards in plumes, and the cool and more dense water near the top of thepot likewise sinks.

Natural convection will be more likely and/or more rapid with a greatervariation in density between the two fluids, a larger acceleration due togravity that drives the convection, and/or a larger distance through theconvecting medium. Natural convection will be less likely and/or less rapidwith more rapid diffusion (thereby diffusing away the thermal gradient that is

causing the convection) and/or a more viscous (sticky) fluid.The onset of natural convection can be determined by the Rayleighnumber (Ra).

Note that differences in buoyancy within a fluid can arise for reasons otherthan temperature variations, in which case the fluid motion iscalled gravitational convection (see below). However, all types of buoyantconvection, including natural convection, do not occurin microgravity environments. All require the presence of an environmentwhich experiences g-force (proper acceleration).

[edit]Forced convection


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Main article:Forced convection

In forced convection, also called heat advection, fluid movement resultsfrom external surface forces such as a fan or pump. Forced convection istypically used to increase the rate of heat exchange. Many typesof mixing also utilize forced convection to distribute one substance withinanother. Forced convection also occurs as a by-product to other processes,such as the action of a propeller in a fluid or aerodynamic heating. Fluidradiator systems, and also heating and cooling of parts of the body by bloodcirculation, are other familiar examples of forced convection.

Forced convection may happen by natural means, such as when the heat ofa fire causes expansion of air and bulk air flow by this means. Inmicrogravity, such flow (which happens in all directions) along with diffusion

is the only means by which fires are able to draw in fresh oxygen to maintainthemselves. The shock wave that transfers heat and mass out of explosionsis also a type of forced convection.

Although forced convection from thermal gas expansion in zero-g does notfuel a fire as well as natural convection in a gravity field, some types ofartificial forced convection are far more efficient than free convection, asthey are not limited by natural mechanisms. For instance, a convectionoven works by forced convection, as a fan which rapidly circulates hot airforces heat into food faster than would naturally happen due to simple

heating without the fan.

The rate of radiative energy emission from a hot surface is given by theStefan-

Boltzmann law .

Here P is the power emitted from the area, and E is the energy contained by the

object. For very hot objects, the role of the ambient temperature can be neglected.

If the hot temperature is more than 3.16 times the ambient, then the contribution

of ambient terms is less than 1%. For example, for 300K ambient on the earth, an

object of temperature higher than 1000K can be treated like a pure radiator into

space. If the heat loss is purely radiative and not limited by heat transfer to the

radiating surface, then the cooling time can be modeled for a hot object.


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If the energy of the object can be characterized by pure translational kinetic energy

according to equipartition of energy, then

What is the significance of specific speed ?

The specific speed inversely proportional to the head across the machine. So low

specific speed corresponds to high head across it and vice-versa. The specific speed

is directly proportional to the discharge through the machine or power produced

by the machine. So low specific speed therefore refers to low discharge or low

power machine and vice-versa.

Low head turbine - Kaplan turbine

Medium head turbine - Francis turbine

High head turbine - Pelton wheel.

Drop Forging

Drop forging is a process used to shape metal into complex shapes by

dropping a heavy hammer with a die on its face onto the work piece.For monoatomic;\

For diatomic;

For polytropic;

Heat conduction, also called diffusion, is the direct microscopic exchange of kinetic

energy of particles through the boundary between two systems. When an object is

at a different temperature from another body or its surroundings, heat flows so

that the body and the surroundings reach the same temperature, at which point


7/27

they are in thermal equilibrium. Such spontaneous heat transfer always occurs

from a region of high temperature to another region of lower temperature, as

required by the second law of thermodynamics.

Heat convection occurs when bulk flow of a fluid (gas or liquid) carries heat alongwith the flow of matter in the fluid. The flow of fluid may be forced by external

processes, or sometimes (in gravitational fields) by buoyancy forces caused when

thermal energy expands the fluid (for example in a fire plume), thus influencing its

own transfer. The latter process is often called "natural convection". All convective

processes also move heat partly by diffusion, as well. Another form of convection

is forced convection. In this case the fluid is forced to flow by use of a pump, fan or

other mechanical means.

The final major form of heat transfer is by radiation, which occurs in any

transparent medium (solid or fluid) but may also even occur across vacuum (as

when the Sun heats the Earth). Radiation is the transfer of energy through space

by means of electromagnetic waves in much the same way as electromagnetic

light waves transfer light. The same laws that govern the transfer of light govern

the radiant transfer of heat.[1]

The fundamental modes of heat transfer are:

Conduction or diffusion

The transfer of energy between objects that are in physical contact

Convection

The transfer of energy between an object and its environment, due to fluid motion

Radiation

The transfer of energy to or from a body by means of the emission or absorption of

electromagnetic radiation

Advection

The transfer of energy from one location to another as a side effect of physically

moving an object containing that energy


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High speed steels belong to the Fe-C-X multi-component alloy system where X

representschromium, tungsten, molybdenum,vanadium, or cobalt. Generally, the

X component is present in excess of 7%, along with more than 0.60%carbon.

(However, their alloying element percentages do not alone bestow the hardness-

retaining properties; they also require appropriate high-temperature heat

treatment in order to become true HSS; see History above.)

In the unified numbering system (UNS), tungsten-type grades (e.g. T1, T15) are

assigned numbers in the T120xx series, while molybdenum (e.g. M2, M48) and

intermediate types are T113xx. ASTM standards recognize 7 tungsten types and 17

molybdenum types.[6]

The addition of about 10% of tungsten and molybdenum in total maximisesefficiently the hardness and toughness of high speed steels and maintains these

properties at the high temperatures generated when cutting metals.

The horizontal elements of the "I" are flanges, while the vertical element is

the web. The web resists shear forces while the flanges resist most of the bending

moment experienced by the beam.Beam theory shows that the I-shaped section is

a very efficient form for carrying both bendingand shearloads in the plane of the

web. On the other hand, the cross-section has a reduced capacity in the transversedirection, and is also inefficient in carrying torsion, for which hollow structural

sections are often preferred.

Induction hardening is a form of heat treatment in which a metal part is heated

by induction heatingand then quenched. The quenched metal undergoes

a martensitic transformation, increasing the hardnessand brittleness of the part.

Induction hardening is used to selectively harden areas of a part or assembly

without affecting the properties of the part as a whole.

The planer is especially adapted to large work: the shaper can do

only small work. On the planer the work is moved against a

stationary tool: on the shaper the tool moves across the work,

which is stationary. On the planer the tool is fed into the work; on

the shaper the work is usually fed across the tool. The drive on the

planer table is either by gears or by hydraulic means. The shaper

ram also can be driven in this manner, but many times a quick-return link mechanism is used.


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In surveying the Jacob's staff, contemporaneously referred to as ajacobstaff, is a single straight rod or staff made of nonferrous material, pointedand metal-clad at the bottom for penetrating the ground.[16] It also has ascrew base and occasionally a ball joint on the mount, and is used for

supporting a compass, transit, or other instrument.[17]

The term cross-staffmay also have a different meaning in the history ofsurveying. While the astronomical cross-staff was used in surveying formeasuring angles, two other devices referred to as a cross-staff were alsoemployed.[18]

1. Cross-head, cross-sight, surveyor's cross or cross - a drum or boxshaped device mounted on a pole. It had two sets of mutuallyperpendicular sights. This device was used by surveyors to measure

offsets. Sophisticated versions had a compass and spirit levels on thetop. The French versions were frequently eight-sided rather thanround.[18]

2. Optical square - an improved version of the cross-head, the opticalsquare used two mirrors at 45 to each other. This permitted thesurveyor to see along both axes of the instrument at once

Newtons law of cooling;

ThePelton wheel is an impulse turbine which is among the most efficient types

of water turbines. It was invented by Lester Allan Pelton in the 1870s. The Pelton

wheel extracts energy from the impulse (momentum) of moving water, as opposed

to its weight like traditional overshot water wheel. Although many variations of

impulse turbines existed prior to Pelton's design, they were less efficient than

Pelton's design; the water leaving these wheels typically still had high speed, and

carried away much of the energy. Pelton's paddle geometry was designed so that

when the rim runs at the speed of the water jet, the water leaves the wheel with

very little speed, extracting almost all of its energy, and allowing for a very efficient

turbine.

===Suppose we add a set of two members and a joint again, we get a perfect

frame as shown in figure 3. Hence for a perfect frame the number of joints and

number of members are given by, n=2j-3

Where, n= number of members and j=number of joints


10/27

The Prandtl number is a dimensionless number; the ratio of momentumdiffusivity (kinematic viscosity) to thermal diffusivity. It is named after theGerman physicist Ludwig Prandtl.

It is defined as:

where:

: kinematic viscosity, , (SI units : m2/s)

: thermal diffusivity, , (SI units : m2/s)

: dynamic viscosity, (SI units : Pa s = (N s)/m2)

: thermal conductivity, (SI units : W/(m K) )

: specific heat, (SI units : J/(kg K) ) : density, (SI units : kg/m3 ).

Note that whereas the Reynolds number and Grashof number aresubscripted with a length scale variable, the Prandtl number contains nosuch length scale in its definition and is dependent only on the fluid andthe fluid state.

For mercury, heat conduction is very effective compared to convection:thermal diffusivity is dominant. For engine oil, convection is very effective in

transferring energy from an area, compared to pure conduction: momentumdiffusivity is dominant.

In heat transfer problems, the Prandtl number controls the relative thicknessof the momentum and thermal boundary layers. When Pris small, it meansthat the heat diffuses very quickly compared to the velocity (momentum).This means that for liquid metals the thickness of the thermal boundary layeris much bigger than the velocity boundary layer.

The mass transfer analog of the Prandtl number is the Schmidt number.

Positive displacement pumpA positive displacement pump causes a fluid to move by trapping a fixedamount of it and then forcing (displacing) that trapped volume into thedischarge pipe.

Some positive displacement pumps work using an expanding cavity on thesuction side and a decreasing cavity on the discharge side. Liquid flows intothe pump as the cavity on the suction side expands and the liquid flows outof the discharge as the cavity collapses. The volume is constant given eachcycle of operation.


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Pumps can be arranged in serial or parallel to provide an additional head orflow rate capacity.

Pumps in Serial - Head Added

When two (or more) pumps are arranged in serial their resulting pumpperformance curve is obtained by adding their heads at the same flow rateas indicated in the figure below.

Centrifugal pumps in series are used to overcome larger system head lossthan one pump can handle alone.

for two identical pumps in series the head will be twice the head of asingle pump at the same flow rate - as indicated in point 2.

With a constant flowrate the combined head moves from 1 to 2.

Note! In practice the combined head and flow rate moves along the systemcurve to point 3.

point 3 is where the system operates with both pumps running point 1 is where the system operates with one pump running

Series operation of single stage pumps is seldom encountered - more oftenmultistage centrifugal pumps are used.

Pumps in Parallel - Flow Rate Added

When two or more pumps are arranged in parallel theirresulting performance curve is obtained by adding their flowrates at thesame head as indicated in the figure below.


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Centrifugal pumps in parallel are used to overcome larger volume flows thanone pump can handle alone.

for two identical pumps in parallel, and the head is kept constant, theflowrate doubles as indicated with point 2 compared to a single pump

Note! In practice the combined head and volume flow moves along thesystem curve as indicated from 1 to 3.

point 3 is where the system operates with both pumps running point 1 is where the system operates with one pump running

In practice, if one of the pumps in parallel or series stops, the operationpoint moves along the system resistance curve from point 3 to point 1 - thehead and flow rate are decreased.

A hygrometer is a device used for measuring the humidity of air. Relative

humidity is a term used to describe the amount of water vapor in a mixture of air

and water vapor. It is defined as the ratio of the partial pressure of water vapor in

the air-water mixture to the saturated vapor pressure of a flat sheet of pure water

at those conditions. The relative humidity of air depends not only on temperature

but also on the pressure of the system of interest. Relative humidity is often used

instead of absolute humidity in situations where the rate of water evaporation is

important, as it takes into account the variation in saturated vapor pressure.

A rivet is a permanent mechanical fastener. Before being installed a rivetconsists of a smooth cylindrical shaft with a head on one end. The endopposite the head is called the buck-tail. On installation the rivet is placed in

a punched or pre-drilled hole, and the tail is upset, or bucked(i.e.,deformed), so that it expands to about 1.5 times the original shaft diameter,


13/27

holding the rivet in place. To distinguish between the two ends of the rivet,the original head is called the factory headand the deformed end is calledthe shop heador buck-tail.

Because there is effectively a head on each end of an installed rivet, it can

support tension loads (loads parallel to the axis of the shaft); however, it ismuch more capable of supporting shear loads (loads perpendicular to theaxis of the shaft). Bolts and screws are better suited for tension applications.

Fastenings used in traditional wooden boat building, like copper nailsand clinch bolts, work on the same principle as the rivet but were in use longbefore the term rivetcame about and, where they are remembered, areusually classified among the nails and bolts respectively.

Solid rivets are used in applications where reliability and safety count. A

typical application for solid rivets can be found within the structural partsof aircraft. Hundreds of thousands of solid rivets are used to assemble the

frame of a modern aircraft. Such rivets come with rounded (universal) or

100countersunkheads. Typical materials for aircraft rivets

are aluminiumalloys (2017, 2024, 2117, 7050, 5056, 55000, V-65), titanium,

and nickel-based alloys (e.g.Monel). Some aluminum alloy rivets are too

hard to buck and must be softened by annealing prior to being bucked. "Ice

box" aluminum alloy rivets harden with age, and must likewise be annealed

and then kept at sub-freezing temperatures (hence the name "ice box") toslow the age-hardening process. Steel rivets can be found in static

structures such as bridges, cranes, and building frames

Soft materials are used to make rivets.

Processes

Roll bending

Roll bending produces a cylindrical shaped product from plate or steelmetal.[10]

Roll forming


14/27

Roll forming is a continuous bending operation in which a long strip of metal(typically coiled steel) is passed through consecutive sets of rolls, or stands,each performing only an incremental part of the bend, until the desiredcross-section profile is obtained. Roll forming is ideal for producing partswith long lengths or in large quantities. There are mainly 3 main processes,4 rollers, 3 rollers and 2 rollers, and have different advantages according to

the specifications of the plate (thickness length and diameter) and theshapes.

Also call roll bending or plate rolling process this is used in many fields,Exhaust pipes, Trucks brakes, Pressure Vessel Tanks Gaz tanks,Components for airbags, Fire extinguishers, Hot water boilers, Drawer rails,Filter housings, Fittings, Fuel filters, Gear components, Gear selector forks,Multi diameter Shells, Pressurized containers, Pumps' shells, Rear axles,Sink mountings, Spinning compatible tubes, Washing drumbs.

Flat rolling

Flat rolling is the most basic form of rolling with the starting and endingmaterial having a rectangular cross-section. The material is fed in betweentwo rollers, called working rolls, that rotate in opposite directions. The gapbetween the two rolls is less than the thickness of the starting material,which causes it todeform. The decrease in material thickness causes thematerial to elongate. The friction at the interface between the material and

the rolls causes the material to be pushed through. The amount ofdeformation possible in a single pass is limited by the friction between therolls; if the change in thickness is too great the rolls just slip over thematerial and do not draw it in.[1] The final product is either sheet or plate,with the former being less than 6 mm (0.24 in) thick and the latter greaterthan; however, heavy plates tend to be formed using a press, which istermed forming, rather than rolling.[citation needed]

Oftentimes the rolls are heated to assist in the workability of the metal.Lubrication is often used to keep the workpiece from sticking to the

rolls.[citation needed] To fine tune the process the speed of the rolls and thetemperature of the rollers are adjusted.[12]


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Foil rolling

Foil rollingis a specialized type of flat rolling, specifically used toproduce foil, which is sheet metal with a thickness less than 200 m(0.0079 in).[citation needed] The rolling is done in a cluster millbecause the small

thickness requires a small diameter rolls.[6] To reduce the need for smallrolls pack rollingis used, which rolls multiple sheets together to increase theeffective starting thickness. As the foil sheets come through the rollers, theyare trimmed and slitted with circular or razor-like knives. Trimming refers tothe edges of the foil, while slitting involves cutting it into severalsheets.[12]Aluminum foil is the most commonly produced product via packrolling. This is evident from the two different surface finishes; the shiny sideis on the roll side and the dull side is against the other sheet of foil.[13]

Ring rolling

Ring rolling is a specialized type of hot rolling that increases the diameter ofa ring. The starting material is a thick-walled ring. This workpiece is placedbetween two rolls an idler roll, while another roll, called the driven roll,presses the ring from the outside. As the rolling occurs the wall thicknessdecreases as the diameter increases. The rolls may be shaped to formvarious cross-sectional shapes. The resulting grain structure iscircumferential, which gives better mechanical properties. Diameters can beas large as 8 m (26 ft) and face heights as tall as 2 m (79 in). Commonapplications include rockets,turbines, airplanes, pipes, and pressurevessels.[7]

The distance between each thread is called the "pitch". The majority of screws aretightened by clockwise rotation, which is termed a right-hand thread; a

common mnemonic devicefor remembering this when working with screws or

bolts is "lefty-loosy, righty-tighty." Screws with left-hand threads are used in

exceptional cases. For example, when the screw will be subject to

counterclockwise torque (which would work to undo a right-hand thread), a left-

hand-threaded screw would be an appropriate choice. The left side pedal of

a bicycle has a left-hand thread.


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More generally, screw may mean any helical device, such as a clamp,

a micrometer, a ship's propeller or anArchimedes' screw water pump.

Screws and bolts may be made from a wide range of materials, with steel being

perhaps the most common, in many varieties. Where great resistance to weatheror corrosion is required, stainless steel, titanium, brass (steel screws can discolor

oak and other woods), bronze, monel or silicon bronze may be used. Galvanic

corrosion of dissimilar metals can be prevented (usingaluminium screws for

double-glazing tracks for example) by a careful choice of material. Some types of

plastic, such asnylon or polytetrafluoroethylene(PTFE), can be threaded and used

for fastenings requiring moderate strength and great resistance to corrosion or for

the purpose of electrical insulation. Often a surface coating is used to protect the

fastening from corrosion (e.g. Bright Zinc Plating for steel screws), to impart a

decorative finish (e.g. jappaning) or otherwise alter the properties of the base

material. Selection criteria of the screw materials include temperature, required

strength, resistance to corrosion, joint material and cost.

The leadis defined as the linear distance the screw travels in onecomplete revolution (360) of the shaft. The lead determinesthe mechanical advantage of the screw; the smaller the lead, the higher

the mechanical advantage.[19] The pitchis defined as the axial distance between the crests of adjacent

threads.

everyday siphons, atmospheric pressure is the driving mechanism, The uphill flow

of water in a siphon doesnt violate the principle of continuity because the mass of

water entering the tube and flowing upwards is equal to the mass of water f lowing

downwards and leaving the tube. A siphon doesn't violate the principle

of conservation of energy because the loss of gravitationalpotential energy as

liquid flows from the upper reservoir to the lower reservoir equals the work donein overcoming fluid friction as the liquid flows through the tube. The maximum

height of the crest is limited by atmospheric pressure, the density of the liquid, and

itsvapour pressure. When the pressure within the liquid drops to below the liquid's

vapor pressure, tiny vapor bubbles can begin to form at the high point and the

siphon effect will end.

Diametral Pitch

Pitch diameter

Number of teeth

Divide the number of

teeth by the pitchdiameter Pd = N / D


17/27

The greatest advantage of square threads is that they have a much higherintrinsic efficiency than acme threads. Due to the lack of a thread

angle there is no radial pressure, or bursting pressure, on the nut. This alsoincreases the nut life.[1]

The greatest disadvantage is the difficulty in machining such a thread.The single-point cutting tools or taps and dies used to cut the thread cannothave efficient rake and relief angles (because of the square form), whichmakes the cutting slow and difficult. Square threads also cannot carry asmuch load as a trapezoidal thread, because the root of the square thread issmaller. Also, there is no way to compensate for wear on the nut, so it mustbe replaced when worn out.[1]

One way is to define the stream function for a two dimensional flow such that

the flow velocity can be expressed as:

A common method to remove systematic error is through calibration of the

measurement instrument.

Random error is always present in a measurement. It is caused byinherently unpredictable fluctuations in the readings of a measurementapparatus or in the experimenter's interpretation of the instrumental reading.Random errors show up as different results for ostensibly the samerepeated measurement. They can be estimated by comparing multiple

measurements, and reduced by averaging multiple measurements.Systematic error cannot be discovered this way because it always pushesthe results in the same direction. If the cause of a systematic error can beidentified, then it can usually be eliminated.

Because random errors are reduced by re-measurement (making ntimes asmany measurements will usually reduce random errors by a factor of n), itis worth repeating an experiment until random errors are similar in size tosystematic errors. Additional measurements will be of little benefit, becausethe overall error cannot be reduced below the systematic error.


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Tempering is done immediately after quench hardening. When the steel cools to

about 40 C (104 F) after quenching, it is ready to be tempered. The part is

reheated to a temperature of 150 to 400 C (302 to 752 F). In this region a softer

and tougher structure Troostite is formed. Alternatively, the steel can be heated to

a temperature of 400 to 700 C (752 to 1292 F) that results in a softer structure

known as Sorbite. This has less strength than Troostite but more ductility and

toughness.

Poissons Ratio;

For a perfectly isotropic elastic material, Poisson's Ratio is 0.25, but for most

materials the value lies in the range of 0.28 to 0.33.

E = 2 (1 + n) G.

Lame's constantsare derived from modulus of elasticity and Poisson's ratio.

Common forms of the equation of state of an ideal gas: PV = nRuT

PV = mRT

where n is the number of moles, Ru is the universal gas constant, and R is the

specific gas constant. The universal and specific gas constants are related as

follows: R=Ru/M, where M is the molecular weight of the gas.

In heat transfer analysis, thermal diffusivity is the thermal conductivity divided by

density and specific heat capacity at constant pressure. It has the SI unit of m/s.

The formula is:

System

Heat (+)

Work (+)


19/27

where

is thermal conductivity (W/(mK))

is density (kg/m)

is specific heat capacity (J/(kgK))

The denominator can be considered the volumetric heat capacity (J/(mK)).

The main limitation with thermocouples is accuracy and system errors of less than

one degree Celsius(C) can be difficult to achieve.[3]

Any junction of dissimilar metals will produce an electric potential related to

temperature. Thermocouples for practical measurement of temperature are

junctions of specific alloyswhich have a predictable and repeatable relationship

between temperature and voltage. Different alloys are used for different

temperature ranges. Properties such as resistance to corrosion may also be

important when choosing a type of thermocouple. Where the measurement point

is far from the measuring instrument, the intermediate connection can be made by

extension wires which are less costly than the materials used to make the sensor.

Thermocouples are usually standardized against a reference temperature of 0

degrees Celsius; practical instruments use electronic methods of cold-junction

compensation to adjust for varying temperature at the instrument terminals.

Electronic instruments can also compensate for the varying characteristics of the

thermocouple, and so improve the precision and accuracy of measurements.

The three principal Stresses in the Shell arethe Circumferential or Hoop Stress; the Longitudinal Stress; andthe Radial Stress.If the Cylinder walls are thin and the ratio of the thickness to the Internal

diameter is less than about 1/20 then it can be assumed that the hoop and

longitudinal stresses are constant across the thickness. It may also be

assumed that the radial stress is small and can be neglected. In point of fact

it must have a value equal to the pressure on the inside surface and zero at


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the outside surface. These assumptions are within the bounds of reasonable

accuracy.

The Stresses in the cylinder walls are:-

The Stresses in the hemispherical Ends are:-

Since the length of the Circumference = the diameter X a constant FORCYLINDER:

It should be noticed that this is the sum of the linear Strains in threePrincipal directions. Similar reasoning for a Spherical Shell shows that:-

i.e. To increase the capacity it is only necessary to multiply the Volumetric

Strain by the original Volume.

Tool steel refers to a variety of carbon and alloy steels that are particularly well-

suited to be made into tools. Their suitability comes from their distinctivehardness,resistance to abrasion, their ability to hold a cutting edge, and/or their resistance

to deformation at elevated temperatures (red-hardness). Tool steel is generally

used in a heat-treated state.

With a carbon content between 0.7% and 1.5%, tool steels are manufactured

under carefully controlled conditions to produce the required quality.

Themanganese content is often kept low to minimize the possibility of cracking

during water quenching. However, proper heat treatingof these steels is


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important for adequate performance, and there are many suppliers who provide

tooling blanks intended for oil quenching.

Impulse turbines change the direction of flow of a high velocity fluid or gas jet. The

resulting impulse spins the turbine and leaves the fluid flow with diminished

kinetic energy. There is no pressure change of the fluid or gas in the turbine blades

(the moving blades), as in the case of a steam or gas turbine, all the pressure drop

takes place in the stationary blades (the nozzles). Before reaching the turbine, the

fluid'spressure headis changed to velocity headby accelerating the fluid with

a nozzle. Pelton wheelsand de Laval turbinesuse this process exclusively. Impulse

turbines do not require a pressure casement around the rotor since the fluid jet is

created by the nozzle prior to reaching the blading on the rotor. Newton's secondlaw describes the transfer of energy for impulse turbines.

Reaction turbines develop torque by reacting to the gas or fluid's pressure or mass.

The pressure of the gas or fluid changes as it passes through the turbine rotor

blades. A pressure casement is needed to contain the working fluid as it acts on

the turbine stage(s) or the turbine must be fully immersed in the fluid flow (such as

with wind turbines). The casing contains and directs the working fluid and, for

water turbines, maintains the suction imparted by the draft tube. Francis

turbinesand most steam turbinesuse this concept. For compressible working

fluids, multiple turbine stages are usually used to harness the expanding gas

efficiently. Newton's third lawdescribes the transfer of energy for reaction

turbines.

Crossflow turbinesare designed as an impulse machine, with a nozzle, but in low

head applications maintain some efficiency through reaction, like a traditional

water wheel.

Water turbines

Pelton turbine, a type of impulse water turbine.

Francis turbine, a type of widely used water turbine.

Kaplan turbine, a variation of the Francis Turbine.

Turgo turbine, a modified form of the Pelton wheel.


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Cross-flow turbine, also known as Banki-Michell turbine, or Ossberger

turbine.

simple bending theory equation

quivalent Bending Moment :

Now let us define the term the equivalent bending moment which acting

alone, will produce the same maximum principal stress or bendingstress.Let Me be the equivalent bending moment, then due to bending

Equivalent Torque :

At we here already proved that 1 and 2 for the combined bending andtwisting case are expressed by the relations:


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where is defined as the equivalent torque, which acting alone would

produce the same maximum shear stress as produced by the pure torsion

Thus,

Vena contracta is the point in a fluid stream where the diameter of the stream is

the least, and fluid velocity is at its maximum, such as in the case of a stream

issuing out of a nozzle, (orifice).

Coefficient of contraction:

It is the ratio between the area of the jet at the vena contracta to the area of the

orifice.

Cc = area at vena contracta/ area of orifice

The typical value may be taken as 0.64 for a sharp orifice (concentric with the flow

channel). The smaller the value, the more effect the vena contracta has.

A vortex (plural:vortices) is a spinning, often turbulent, flow of fluid.

Anyspiral motion with closed streamlines is vortex flow. The motion of the fluid

swirling rapidly around a center is called a vortex. The speed and rate of rotation of

the fluid in a free (irrotational) vortex are greatest at the center, and decrease

progressively with distance from the center, whereas the speed of a forced

(rotational) vortex is zero at the center and increases proportional to the distance


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from the center. Both types of vortices exhibit a pressure minimum at the center,

though the pressure minimum in a free vortex is much lower.

Free (irrotational) vortex

When fluid is drawn down a plug-hole, one can observe the phenomenon ofa free vortex or line vortex. The tangential velocity vvaries inversely asthe distance rfrom the center of rotation, so the angular momentum rvisuniform everywhere throughout the flow; the vorticity is zero everywhere(except for a singularity at the center-line) and the circulation about acontour containing r= 0 has the same value everywhere.[1] The freesurface (if present) dips sharply (as r2 ) as the center line is approached.

The tangential velocity is given by:

where is the circulation and r is the radial distance from the center ofthe vortex.

In non-technical terms, the fluid near the center of the vortex circulatesfaster than the fluid far from the center. The speed along the circular pathof flow decreases as you move out from the center. At the same time theinner streamlines have a shorter distance to travel to complete a ring. Ifyou were running a race on a circular track would you rather be on the

inside or outside, assuming the goal was to complete a circle? Imagine aleaf floating in a free vortex. The leaf's tip points to the center and theblade straddles multiple streamlines. The outer flow is slow in terms ofangle traversed and it exerts a backwards tug on the base of the leafwhile the faster inner flow pulls the tip forwards. The drag force opposesrotation of the leaf as it moves around the circle.

Forced (rotational) vortex

In a forced vortex the fluid rotates as a solid body (there is no shear).The motion can be realized by placing a dish of fluid on a turntable

rotating at radian/s; the fluid has vorticity of 2 everywhere, and thefree surface (if present) is a paraboloid.

The tangential velocity is given by:[1]

where is theangular velocity and r is the radial distance from the center ofthe vortex.


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Halsey premium plan:

Various modifications of piece work have been developed , all

involving the features of a minimum task and of a premium for

performance beyond that point. These plans are called "premiumplans," "progressive wage systems," and "gain sharing." One of

the first of these, Halsey's premium plan, fixes a standard time for

a job, and if the worker falls short of, or merely attains to, that

standard he gets the regular pay; but if he takes less than the

standard time he receives a fixed premium per hour equal to one

third of the wage for the time saved. For example, if the standard

time is 10 hours for a $3 job the premium for speed is ten cents

per hour, and the worker would receive 20 cents premium if he did

the work in 8 hours ($2.40 + 20, total $2.60), and 50 cents

premium if he did it in 5 hours ($1.50 + 50, total $2.00). His

average wage per hour thus rises as his speed increases; it

becomes 32.5 cents per hour when the job is done in 8 hours, and

40 cents per hour when the job is done in 5 hours. The reduction

of cost per job to the employer evidently would be 40 cents in the

first case and $1 in the second. This is Halsey's plan, by which theworker gets one-third and the employer two-thirds of the time

saved.

The idler pulley is often the point that is adjusted to replace a belt. Pulley

replacement often includes replacing one or more belts. Mechanics talk about an

idler pulley tensioner that helps provide the right level of tension on the belt.

Vehicle owners can often adjust the pulley with a screw to gain or lose tension. The

owner of the vehicle can also move the idler pulley to release tension so that thebelt can slip over the pulley. They can then turn the tensioner to regain the correct

level of tension to keep the belt tight and ensure correct operation.

Wien's displacement law states that the wavelength distribution of thermal

radiation from a black body at any temperature has essentially the same shape as

the distribution at any other temperature, except that each wavelength is

displaced on the graph. Apart from an overall T3multiplicative factor, the

average thermal energy in each mode with frequency only depends on theratio . Restated in terms of the wavelength , the distributions at


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corresponding wavelengths are related, where corresponding wavelengths are at

locations proport ional to . Blackbody radiation approximates to Wien's law at

high frequencies.

From this general law, it follows that there is an inverse relationship between the

wavelength of the peak of the emission of a black body and itstemperaturewhen

expressed as a function of wavelength, and this less powerful consequence is often

also called Wien's displacement law in many textbooks.

In terms of frequency (in hertz), Wien's displacement law becomes

BLADE RATIO

Both ends hinged N=1 Eulers critical load

P=

One fix other free N=.25

One fix other hinge N=2

Both fix N=4

One fix ther roller N=1

For Kinametic chain, L=2/3(J+2)

For pump;

qD 3 q -- N

H D^2 HN^2

HP D^5 HP N^3

EXTERING FORCE = p A v2


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For pump ; for turbine;

=

=

Belt problem:

Power transmitted = (T1-T2)*v/75 N1/N2 = d2 / d1

For shaft compounding; for pipe compounding;

l/ d4 = constant l/ d5 = constant

Re = Inertial force/viscous force

Fraude = Dynamic force / weight

Weber = Inert ial force / surface tension

Mach = Inert ial force / elastic force

For lamellar flow; for turbulent;

=

5

=

0.37

.

Max shear stress for circular shaft and rectangular shaft =

= 16T/(d3) and = T/(bt2)

Power screws;

Effieciency =

if greater than helix angle then self locking

the section of the shaft

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