Cooling of Turbine Blades:

Cooling of Turbine Blades:-
For same pressure ratio at high maximum temperature
thermal efficiency is high. But the high temperature can
lead to the damage of the turbine. So the cooling of
blade becomes essential.
Methods of Cooling :-
Cooling of components can be achieved by air or liquid
cooling. Liquid cooling seems to be more attractive
because of high specific heat capacity and chances of
evaporative cooling but there can be problem of leakage,
corrosion, choking,etc. which works against this method.
On the other hand air cooling allows to discharge air
into main flow without any problem. Quantity of air
required for this purpose is 1-3% of main flow and blade
temperature can be reduced by 200-300°C.

Bevel gears and its applications:

Bevel gears and its applications:-
Bevel gears are the gears where the axes of the two shafts
intersect and the tooth-bearing faces of the gears
themselves are conically shaped. Bevel gears are most often
mounted on shafts that are 90 degrees apart, but can be
designed to work at other angles as well. The pitch surface
of bevel gears is a cone.
Applications:
1)Bevel gears are used in differential drives, which can
transmit power to two axles spinning at different speeds,
such as those on a cornering automobile.
2)Bevel gears are used as the main mechanism for a hand
drill. As the handle of the drill is turned in a vertical
direction, the bevel gears change the rotation of the chuck to
a horizontal rotation. The bevel gears in a hand drill have the
added advantage of increasing the speed of rotation of the
chuck and this makes it possible to drill a range of
materials.
3)The gears in a bevel gear planer permit minor adjustment
during assembly and allow for some displacement due to
deflection under operating loads without concentrating the
load on the end of the tooth.
4)Spiral bevel gears are important components on rotorcraft
drive systems. These components are required to operate at
high speeds, high loads, and for a large number of load
cycles. In this application, spiral bevel gears are used to
redirect the shaft from the horizontal gas turbine engine to
the vertical rotor.

Axial vector engine

Axial vector engine 12 cylinder concept 26500cc/1618ci in
SolidWorks
Cylinders =12 (6 both sides)
Bore Dia = 80mm
Stroke length = 110mm
Engine Type = Axial Vector Type 4 Stroke
Crank Mechanism = CAM Disk Mechanism
Engine Capacity = 26500cc/1618ci
A swashplate is rigidly fixed to the CAMDisk, and goes round
with it as a unit. Therefore the connecting rods are not fixed
to the plate in any way, but push on it with rollers or slipper
pads that can glide over the surface of the plate as it turns.
The main point of attraction is the use of CAM-Disk in place
of Crank shaft to provide reciprocation. Since the Engine is
double Reciprocatory with corresponding strokes at both
sides, there is no unbalancing of masses i.e. full balanced.
Battery Ignition System is used with a spark plug for each
cylinder. There are one inlet and one exhaust for each
cylinder. Fins thickness is not calculated but 5mm is more
than enough. Fuel Type used is Gasoline and the engine can
found application in Aerospace as well as Automotive. Engine
is mainly a torque converter type rather than speeder.

Direct injection

Direct injection:-
With direct injection, the fuel is injected directly into the
combustion chamber which is usually formed by a cavity in
the piston crown.
This cavity is carefully shaped to promote air swirl and the
direction of the injector nozzle ensures that rapid mixing of
the fuel and air assists complete combustion.
Advantages - It is claimed that direct injection gives higher
thermal efficiency with lower fuel consumption. This is
bought about by the fact that no heat is lost or power wasted
in pumping air through a restricted opening into the separate
chamber or in discharging the gases from the chamber. This
gives easier starting and generally this type of engine does
not require a starting aid device, such as glow plugs.
Disadvantages - This kind of injection is prone to “diesel
knock”.

Piston

PISTON-
A piston is a component of reciprocating engines,
reciprocating pumps, gas compressors and pneumatic
cylinders, among other similar mechanisms. It is the moving
component that is contained by a cylinder and is made gas-
tight by piston rings. In an engine, its purpose is to transfer
force from expanding gas in the cylinder to the crankshaft
via a piston rod and/or connecting rod. In a pump, the
function is reversed and force is transferred from the
crankshaft to the piston for the purpose of compressing or
ejecting the fluid in the cylinder. In some engines, the piston
also acts as a valve by covering and uncovering ports in the
cylinder wall.

Triple Spark Technology

What is Triple Spark Technology?
Along with the announcement of the new Pulsar 200NS,came
a new technology named Triple Spark technology. Which is
being used in the new bike. In simple words, the triple spark
technology is nothing but a engine with 3 spark plugs housed
in it.
To make use of 3 spark plugs, the pulsar engine houses a
pent roof combustion chamber which in turn allows to house
3 spark plugs in the engine chamber. Out of the three plugs,
the primary plug is the center one and is mounted in an
angle and enters the chamber at the top-center. The other
two secondary plugs are mounted below, each opposite each
other and one of them being vertically underneath the
primary plug.
The secondary plugs fires a bit after the primary one has
fired and the timings are controlled by the ECU depending on
various parameters like throttle position, engine revs,load on
engine and many other stuffs. According to Bajaj, these plugs
gain a advantage in low-rev riding condition where it
extracts the best economy.Compared to KTM Duke 200 in
similar conditions it gives as much as 10-13kmpl
more,however the difference vanishes at higher revs and
high speed.

Jet engine

A jet engine operates on the application of Sir Isaac
Newton's third law of physics.This is a picture of how
the air flows through a jet engine.
Jet engines move the airplane forward with a great force
that is produced by a tremendous thrust and causes the
plane to fly very fast.
All jet engines, which are also called gas turbines, work
on the same principle. The engine sucks air in at the
front with a fan. A compressor raises the pressure of the
air. The compressor is made up of fans with many
blades and attached to a shaft. The blades compress
the air. The compressed air is then sprayed with fuel and
an electric spark lights the mixture. The burning gases
expand and blast out through the nozzle, at the back of
the engine. As the jets of gas shoot backward, the
engine and the aircraft are thrust forward.

INJECTOR PRESSURE in heavy vehicles?

Q. What is an INJECTOR PRESSURE in heavy vehicles?
Why it is used?
A. Injector pressure i s the pressure at which the fuel can
be injected into the vehicle. In heavy vehicles, injector
pressure is 220 kg/cm square. It is used to set up the
standard fuel injection in the vehicles. With the help of
injector pressure we can calculate the amount of fuel
needed, through the following formula:
Est. Horsepower x B.S.F.C / No. of injectors x duty cycle
= lb/hr per injector
cc = lb/hr x 10.5

CARBURETOR

CARBURETOR
--------------------
The components of the carburetor consist
of: •Float chamber •Float valve •Jet nozzle •Venturi
•Throttle valve •Accelerator pedal •Choke •Fuel tank •Fuel
pump •Fuel Filter.
The carburetor is a device that vaporizes gasoline and
mixes it with air in the proper ratio for combustion in an
internal combustion engine. Normally the ratio of fuel to
air is about 1:15 by volume. That is one part fuel to
fifteen parts air. A higher ratio is called a rich mixture
and a lower ratio is called a leaner mixture.

NEW SPLIT-CYCLE ENGINE DESIGN TO IMPROVE FUEL ECONOMY BY 50 PERCENT

NEW SPLIT-CYCLE ENGINE DESIGN TO IMPROVE
FUEL ECONOMY BY 50 PERCENT :
Split cycle engines—engines that split the functions of
a normal four-cycle piston into two separate but
adjacent and complementary pistons—have never
been able to match the efficiency and overall function
of traditional internal combustion engines, but a new
design could change all that. By tweaking the
standard split-cycle design with new features like a
compressed air tank that captures wasted energy
from the system, the Scuderi Group claim not only to
have matched the efficiency of the standard four-
cycle engine, but to have far surpassed it.
The Scuderi Group’s design has drawn interest from
nine major carmakers, the company says, but has
yet to prove the technology in real world prototype
tests. But in computer simulations that install a
Scuderi engine in a 2004 Chevy Cavalier, the split-
cycle engine shows to reduce fuel consumption by 25
to 36 percent, translating roughly to a 50 percent
improvement in overall fuel economy. :
Split cycle engines—engines that split the functions of
a normal four-cycle piston into two separate but
adjacent and complementary pistons—have never
been able to match the efficiency and overall function
of traditional internal combustion engines, but a new
design could change all that. By tweaking the
standard split-cycle design with new features like a
compressed air tank that captures wasted energy
from the system, the Scuderi Group claim not only to
have matched the efficiency of the standard four-
cycle engine, but to have far surpassed it.
The Scuderi Group’s design has drawn interest from
nine major carmakers, the company says, but has
yet to prove the technology in real world prototype
tests. But in computer simulations that install a
Scuderi engine in a 2004 Chevy Cavalier, the split-
cycle engine shows to reduce fuel consumption by 25
to 36 percent, translating roughly to a 50 percent
improvement in overall fuel economy.

Regenerative Brake

Technically, you could generate energy by burning
brake pads, but automotive engineers have managed
to come up with a way to use brakes to generate
energy without going up in flames. The technology is
called regenerative braking. At the most basic level,
regenerative braking means re-capturing the kinetic
energy of the vehicle's motion and turning it into
another type of energy. Commonly, this is done by
converting kinetic energy into electricity and
recharging the car's battery with it.

DIFFERENCE BETWEEN A TURBO CHARGER AND A SUPER CHARGER

DIFFERENCE BETWEEN A TURBO CHARGER AND A
SUPER CHARGER
Both turbochargers and superchargers are called
forced induction systems. They compress the air
flowing into the engine. The advantage of
compressing the air is that it lets the engine stuff
more air into a cylinder. More air means that more
fuel can be stuffed in, too, so you get more power
from each explosion in each cylinder. A turbo/
supercharged engine produces more power overall
than the same engine without the charging.
The typical boost provided by either a turbocharger or
a supercharger is 6 to 8 pounds per square inch (psi).
Since normal atmospheric pressure is 14.7 psi at sea
level, you can see that you are getting about 50-
percent more air into the engine. Therefore, you
would expect to get 50-percent more power. It's not
perfectly efficient, though, so you might get a 30-
percent to 40-percent improvement instead.
The key difference between a turbocharger and a
supercharger is its power supply. Something has to
supply the power to run the air compressor. In a
supercharger, there is a belt that connects directly to
the engine. It gets its power the same way that the
water pump or alternator does. A turbocharger, on the
other hand, gets its power from the exhaust stream.
The exhaust runs through a turbine, which in turn
spins the compressor.

Biomimicry

Biomimicry Creates New Tires-
Biomimicry is the science that imitates nature to
create new products.
Resilient Technologies, a Wisconsin based company,
has created a tire that can't go flat.
Instead of using a pressurized aircavity, the tire
design relies on a geometric pattern of six-sided
cells that are arranged in a matrixlike a honeycomb.
It has the same ride, reduced noise levels and heat
generation as pressurized tires. The goal wasto
create an airless tire with uniform flexibility and load
transfer that would endure tremendous wear and tear
and still perform well.
The best design was found in nature, which was the
honeycomb.

2 & 4 Stroke engine Difference

2 & 4 Stroke engine Difference:
In case of two stroke engine, rotation of crank shaft
will be power stroke for every one rotation. During
compression stroke, fuel will flow towards the crank
case(suction) and during power stroke, exhaust will
emit the burnt fuel through the transfer ports.

Important Portals & their Founders

Some Important Portals & their Founders
1. Google — Larry Page & Sergey Brin
2. Facebook— Mark Zuckerberg
3. Yahoo— David Filo & Jerry Yang
4. Twitter— Jack Dorsey & Dick Costolo
5. Internet— Tim Berners Lee
6. Linkdin— Reid Hoffman, Allen Blue& Koonstantin
Guericke
7. Email— Shiva Ayyadurai
8. Gtalk— Richard Wah kan
9. Whats app — Laurel Kirtz
10. Hotmail— Sabeer Bhatia
11. Orkut— Buyukkokten
12. Wikipedia— Jimmy Wales
13. You tube— Steve Chen, Chad Hurley &
JawedKarim
14. Rediffmail— Ajit Balakrishnan
15. Nimbuzz— Martin Smink & Evert Jaap Lugt
16. Myspace— Chris Dewolfe & Tom Anderson
17. Ibibo — Ashish Kashyap
18. OLX— Alec Oxenford & Fabrice Grinda
19. Skype— Niklas Zennstrom,Janus Friis & Reid
Hoffman
20. Opera— Jon Stephenson von Tetzchner & Geir
lvarsoy
21. Mozilla Firefox— Dave Hyatt & Blake Ross
22. Blogger— Evan Willam Belli

Drive shaft

Drive shaft:-
A drive shaft, driveshaft, driving shaft, propeller shaft
(prop shaft), or Cardan shaft is a mechanical
component for transmitting torque and rotation,
usually used to connect other components of a drive
train that cannot be connected directly because of
distance or the need to allow for relative movement
between them.
Drive shafts are carriers of torque: they are subject
to torsion and shear stress, equivalent to the
difference between the input torque and the load.
They must therefore be strong enough to bear the
stress, whilst avoiding too much additional weight as
that would in turn increase their inertia.

supercharger

A supercharger is an engine-driven air pump that
supplies more than the normal amount of air into the
intake manifold and boosts engine torque and power.
It provides an instantaneous increase in power
without delay or lag associated with turbochargers.
Because it is driven by the engine, it requires
horsepower to operate and is not as efficient as a
turbocharger.
In basic concept, a supercharger is an air pump
mechanically driven by the engine itself. Gears,
shafts, chains, or belts from the crankshaft can be
used to turn the pump. This means that the air pump
or supercharger pumps air in direct relation to engine
speed.
types of supercharger
................................
-Roots-type supercharger :-
Named for Philander and Francis Roots, two brothers
from Connersville, Indiana, who patented the design
in 1860 as a type of water pump to be used in mines.
Later used to move air, and used today on two-
stroke cycle Detroit diesel and other supercharged
engines.
The roots-type supercharger is a positive
displacement design. All
air entering is forced through the unit.
-Centrifugal supercharger :-
Mechanically driven by the engine, similar to a
turbocharger but mechanically driven by the engine.
A centrifugal supercharger is not a positive
displacement pump and all of the air that enters is not
forced through the unit. Air enters a centrifugal
supercharger housing in the center and exits at the
outer edges of the compressor wheels at a much
higher speed due to centrifugal force.
Blade speed must be higher than engine speed so a
smaller pulley is used on the supercharger and the
crankshaft overdrives the impeller through an internal
gear box, achieving about seven times the speed of
the engine.
Examples of centrifugal superchargers include
Vortech and Paxton
Supercharger Service
Usually lubricated with synthetic engine oil inside the
unit, the supercharger oil level should be checked and
replaced as specified by the vehicle or supercharger
manufacturer. The drive belt should also be inspected
and replaced as necessary.

difference between Moment and Couple

What is the difference between Moment and Couple?
• Moment of force is the measure of turning effect of
a force about a point. A couple consists of two equal
and opposite forces acting with two different but
parallel lines of action. Each force has its own
moment.
• Moment of a force is dependent on the distance
from the pivot and the magnitude of the force while
the moment of a couple is the net effect of the two
moments of the forces. Moment of a couple is
independent of the location of the point considered. It
is constant throughout the plane. The resultant
moment of a couple is called a torque.
• Torque, also called moment or moment of force, is
the tendency of a force to rotate an object about an
axis, fulcrum, or pivot. Just as a force is a push or a
pull, a torque can be thought of as a twist.
Couple - Two equal but opposite forces
Torque - Moment of a couple

Carburetor used inAutomobiles

Automobile:
Which Carburetor used inAutomobiles?
A carburetor is a device used in petrol or similar
liquid fuel engines by means of which the fuel mixed
with air, is supplied into the induction manifold of the
engine. An engineering or automobile field connected
people will better know this. The main object of the
carburetor is to supply the required quantity of fuel
and air mixture of the correct strength as dedicated
by the load condition of the engine. For this purpose
different types of carburetorsare available in the
market. Out of that, you will find here the details of
Zenith Carburetor, as below. Zenith carburetor is also
known as “British Carburetor” and used by various
famous car manufacturers. This carburetor has also
number of designs available for different purposes.
Construction and Working
In this, float chamber is supplied with fuel from the
fuel tank through a pipe.Whenever the float chamber
falls short of fuel, the fuel from the fuel tank flows
into the chamber at a fastest speed than is consumed
by the engine with the result that, the float rises up, till
it reaches a certain level. At this time, a needle valve
moves down and rest against the seat, resulting the
stoppage of fuel supply from fuel tank.
The main jet is directly connected to the float
chamber while the auxiliary jet which is also called as
compensating jet draws fuel from auxiliary chamber
(Reservoir).Thi s auxiliary chamber is connected to
the float chamber through an orifice. Both, main and
auxiliary jet is openedup in the venturi.
The air to the carburetor is supplied through the
passage. The throttle valve is located at the end of
the carburetor and connected to the engine suction
pipe. The opening andthe closing of the throttle valve
controls the quantity of air-fuel mixture supplied to
the engine suction manifold. An auxiliary nozzle from
auxiliary chamber (Reservoir) is located at one end of
the by-pass and the other end of this nozzle, opens
upnear the throttle valve.
Working at Starting and Low Speed Running
Because of lower velocity of air at the time of starting
or slow speed of the engine, the suction produced at
the venturi is quite insufficient to operatethe main and
the auxiliary jet in nozzle. To improve the velocity of
air, the throttle valve is closed to such an extent that
there is only a small contracted passage is provided
near the end of by-pass. By this, the velocity of air,
passing through the region increases, producing the
high suction, which operates the nozzle at auxiliary
chamber and the air-fuel mixture supplied through
the holes.
There is starting and slow running device is fitted in
reservoir (Auxiliary Chamber).To vary the supply of
air to the nozzle, the set screw given is slackened
and whole assembly is taken out. By the suitable
number of rotation of screw joint, the position
ofauxiliary nozzle is set. The whole device is then
again fitted to the carburetor and tightened the screw.
Working at Normal Running
At this condition, the throttle valve is opened about
66% and as the air entering through the passage,
passes through the venturi, its velocity increases due
to smaller area consequently its pressure drops,
resulting the suction effect. The fuel is sprayed in the
venturi by main and auxiliary nozzle. As the speed of
engine increases, there by producing the greater
suction. Due to this, greater fuel being supplied by the
main nozzle. Since the compensating jet (Auxiliary
Jet) draws fuel from reservoir (Auxiliary Chamber),
which is subjected to atmospheric pressure, through
the air, the quantity of fuel supplied by it to the venturi
does not change to an appreciable extent. This has
the effect of supplying a weaker solution than if only
one jet were provide in which case, the air-fuel
mixture supplied at high speed will be richer then
desired.
Thus the compensating jet enables the air-fuel
mixture of the desirable strength to be supplied. In
fact with correctly proportioned design of various
parts of this carburetor, the fuel supplied by the main
and compensating nozzle can be made to bear
almost a constant ratio to the air supplied.

PSC Books for MECHANICAL ENGINEERING

GATE Books for MECHANICAL ENGINEERING
Sl.NO.
SUBJECT
AUTHOR
1.
ENGINEERING Thermodynamics
P.K. Nag
2.
I.C. Engine
V. Ganeshan
3.
Gas Turbine and Propulsive Systems
Rodger and Kohen
4.
Fluid Mechanics
R.K Banshal
5.
Compressible Flow
Anderson and Yahya
6.
Heat and Mass Transfer
D.S Kumar
7.
Refrigeration and Air Conditioning
C.P Arora
8.
Fluid Machinery
S.S Ratan
9.
Theory of Machines
S.S Ratan
10.
Mechanical Vibration
Grover, V.P Singh
11.
Machine Design
Khurni & V.B Singh
12.
Material Science
I.P Singh
13.
Production Engg.
P.N Rao & Sharma
14.
Industrial Engg.
Savita Sharma
15.
Operations Research
G.H Ryder
16.
Strength of Materials
Timoshenko B.C. Punamia