Supercharger

A SEMINAR REPORT

Seminar Report submitted in partial fulfillment of the requirements for the

award of the degree of B.Tech. in Mechanical Engineering under

Biju Pattnaik University of Technology

bySUSHANT KUMAR

REGD NO:1201229282

Under the Guidance ofAsst. prof. Rashmi Ranjan Senapati

( Department of Mechanical Engineering)

DEPARTMENT OF MECHANICAL ENGINEERING

DRIEMS, CUTTACK, ODISHA

November- 2015CERTIFICATE

This is to certify that the Seminar entitled supercharger presented by Sushant kumar bearing

Registration No. 1201229282 of Mechanical Engineering in DRIEMS has been completed

successfully.

This is in partial fulfilment of the requirements of Bachelor Degree in Mechanical

Engineering under Biju Pattnaik University of Technology, Rourkela, Odisha.

we wish him success in all future endeavors.

Asst. Prof. Rashmi Ranjan Senapati Asst. Prof. Sonali Rath (Seminar guide) (Seminar-In-Charge)

Prof. Deepak Ranjan Biswal

(HOD, Department of Mechanical Engineering)

ACKNOWLEDGEMENTS

I would like to express my deep and sincere gratitude to my guide, Asst. Prof. Rashmi

Ranjan Senapati of Mechanical Engineering for his unflagging support and continuous

encouragement throughout the seminar work. Without his guidance and persistent help this

report would not have been possible.

I must acknowledge the faculties and staffs of Mechanical Engineering for their support.

Its great pleasure to acknowledge my colleagues for helping me.

I am specially grateful to all.

Signature Of The Student

Name : Sushant kumarDepartment of Mechanical Engineering Regd. No : 1201229282

Abstract

To increase the output efficiency of any engine we have to burn more fuel and make bigger

explosion in every cycle. We have two options for this. One way to add power is to build a

bigger engine. But bigger engines, which weigh more and cost more to build and maintain,

are not always better. Another way to add power is to make a normal-sized engine more

efficient. We can accomplish this by forcing more air into the combustion chamber. More air

means more fuel can be added, and more fuel means a bigger explosion and greater

horsepower. This can be done with the help of a supercharger.

A supercharger is basically an air compressor used for forced induction of an internal

combustion engine. It does the same work as that of a compressor, i.e. it compresses the air

being delivered to the combustion chamber of an engine. The greater mass flow-rate provides

more oxygen to support combustion than would be available in a naturally-aspirated engine,

which allows more fuel to be provided and more work to be done per cycle, increasing the

power output of the engine. Thus a supercharger is extra equipment provided in an engine so

as to boost the capacity and the torque of an engine.

Name : Sushant kumar Regd. no : 1201229282 Semester :7th

Branch : Mechanical Engg. Section : A

List of Figure

1.1 A typical supercharger 1

1.2 Working engine equipped with a supercharger 3

2.1 Types of supercharger 4

3.1 Working of Root supercharger 6

3.2 Working of a twin-screw supercharger 7

3.3 Working of a centrifugal supercharger 8

4.1 Root supercharger 10

4.2 Twin-screw supercharger 10

4.3 Centrifugal supercharger 11

Table of Contents

Acknowledgement i

Abstract ii

List of Figure iii

1. INTRODUCTION 1

1.1 Why superchargers? 2

1.2 Principal of working 3

2. Classification of superchargers 4

3. Commonly used superchargers 5

3.1 Roots supercharger. 6

3.2 Twin-Screw Supercharger 7

3.3 Centrifugal Supercharger 8

3.4 History 9

4. Diagrammatic Illustration 10

5. Drives used in Superchargers 12

6. Supercharger, An edge over turbocharger 13

7. Nothing is perfect. 14

8. Conclusion 15

References. 16

1. INTRODUCTION

To increase the output efficiency of any engine we have to burn more fuel and make bigger

explosion in every cycle. We have two options for this. One way to add power is to build a

bigger engine. But bigger engines, which weigh more and cost more to build and maintain,

are not always better. Another way to add power is to make a normal-sized engine more

efficient. We can accomplish this by forcing more air into the combustion chamber. More air

means more fuel can be added, and more fuel means a bigger explosion and greater

horsepower. This can be done with the help of a supercharger.

A supercharger is basically an air compressor used for forced induction of an internal

combustion engine. It does the same work as that of a compressor, i.e. it compresses the air

being delivered to the combustion chamber of an engine. The greater mass flow-rate provides

more oxygen to support combustion than would be available in a naturally-aspirated engine,

which allows more fuel to be provided and more work to be done per cycle, increasing the

power output of the engine.

Thus a supercharger is extra equipment provided in an engine so as to boost the capacity and

the torque of an engine.

A Typical Supercharger

(Fig-1.1)

11.1 WHY SUPERCHARGER ?

A supercharger is used in an engine for various reasons.

Some of the advantages of superchargers are as follows:

Increases the power of an engine.

A supercharger spinning at 50,000 RPM translates to a boost of about six to nine pounds per

square inch (psi).

Increases the torque produced.

An efficiently working engine with supercharger can achieve the same speed in one third of

the time taken by the same engine without supercharger.

Necessary in airplanes and jets as they have less oxygen at high altitudes. So they provide the

sufficient amount of air by compressing it to higher pressure. And ensures complete

combustion.

Higher amount of oxygen in compressed air from supercharger ensures complete combustion

of the fuel.

Complete combustion reduces pollution to some extent.

21.2 PRINCIPLE OF WORKING

“More fuel + More air = Bigger explosion=Greater horsepower”.

Every supercharger works on the same above mentioned tagline.

It is quite evident that to get more output from any engine we need to burn more fuel. More

fuel will result in a bigger explosion in every cycle, which will then push the piston with

more thrust, and consequently this thrust will be transmitted to the wheels with the help of

crank and shaft. Wheels will rotate faster and with more power and that is how it works.

But, to burn more fuel in an engine, we need more air in it (The chemically correct mixture –

(14: 1:: air : fuel) – is essential for an engine to operate perfectly). Thus a supercharger

compresses the air being delivered to the engine so as to supply more air in the same, limited

volume of the cylinder. This ensures complete combustion of the fuel and no unburnt fuel

comes out of the exhaust. Thus the supercharger increases the power output of any engine.

Diagram of a working engine equipped with a supercharger

(Fig-1.2)

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2. CLASSIFICATION OF SUPERCHARGERS

Based on method of compression, Superchargers can be classified as:-

1. Positive-displacement type, which deliver a nearly-fixed volume of air per revolution at all

speeds and a fairly constant level of boost regardless of engine speed.

2. Dynamic compressors rely on accelerating the air to high speed and then exchanging that

velocity for pressure by diffusing or slowing it down & deliver increasing boost with

increasing engine speed.

A supercharger comes in two different variations:

Positive displacement and dynamic compressors.

A positive displacement supercharger pushes air into the engine at a constant speed, while a

dynamic supercharger uses velocity to manipulate the pressure in the air.

In either case, oxygen is compressed as it is delivered to the engine, allowing more power to

be gained from every explosion in the combustion chambers.

Types of supercharger

(Fig-2.1)

43. COMMONLY USED SUPERCHARGERS

Nowadays, there are several types of superchargers used in the engines.

Following are some of the most commonly used superchargers in the market.

o Roots Superchargers

o Twin-Screw Superchargers

o Centrifugal Superchargers

3.1 ROOTS SUPERCHARGER

Constructional features: It consists of two meshing lobes that are fitted on two parallel

shafts. Those lobes resembles to a lobe gear that are in continuous mesh. Both the lobes mesh

in such a manner that the air pockets between these lobes and the side walls goes on

decreasing as air moves from the fill side to the discharge side. Thus the passing air gets

squeezed.

Working of Roots Supercharger: As the meshing lobes spin, air trapped in the pockets

between the lobes is carried between the fill side and the discharge side & large quantities of

air move into the intake manifold and "stack up" to create positive pressure. This pressurized

air is received at the discharge side.

Roots superchargers are usually large and sit on top of the engine.

Roots superchargers are the least efficient supercharger for two reasons:-

1. They add more weight to the vehicle.

2. They provide air in discrete bursts instead of providing in a smooth & continuous

manner.

5

Working of Root supercharger

(Fig-3.1)

6

3.2 TWIN-SCREW SUPERCHARGERS

Constructional features: Twin-Screw Superchargers consist of two meshing lobes that

resemble a set of worm gear. The two gears meshes in such a way that the air pockets

between them goes on decreasing as air moves ahead.

Working of Twin Screw Superchargers: A twin-screw supercharger operates by pulling air

through a pair of meshing lobes that resemble a set of worm gears.

The rotors have a conical taper, which means the air pockets decrease in size as air moves

from the fill side to the discharge side. Thus a twin-screw supercharger compresses the air

inside the rotor housing.

As the air pockets shrink, the air is squeezed into a smaller space.

Thus twin-screw superchargers are more efficient compared to roots supercharger.

They cost more because the screw-type rotors require more precision in the manufacturing

process.

They also make a lot of noise.

The compressed air exiting the discharge outlet creates a whine or whistle that must be

checked with noise suppression techniques.

Working of a twin-screw supercharger

(Fig-3.2)

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3.3 CENTRIFUGAL SUPERCHARGERS

Constructional features: Centrifugal superchargers consist of an impeller with several

blades that rotate at a very high speed at around 50000 rpm. This impeller throws the air

outside due to centrifugal force. It also consists of a diffuser which exchanges the speed for

high pressure.

Working of Centrifugal Supercharger: As the air is drawn in the hub of the impeller,

centrifugal force causes it to radiate outward. The air leaves the impeller at high speed, but

low pressure. A diffuser converts the high-speed, low-pressure air to low-speed, high-

pressure air. Thus pressurized air is achieved.

Impeller speeds can reach ‘50,000 to 60,000 RPM’.

Centrifugal superchargers are the most efficient and the most common induction systems.

They are small, lightweight and attachable to the front of the engine.

Thus the centrifugal superchargers are the best among the above list.

Working of a centrifugal supercharger

(Fig-3.3)

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3.4 HISTORY OF SUPERCHARGERS

The Roots supercharger is the oldest design of supercharger used in any type of engine.

Philander and Francis Roots, in 1860, introduced the concept of such type of equipment.

Though they patented the design as a machine that would help ventilate mine shafts, later this

turned out to be a miraculous invention for automotive engineers.

In 1900, Gottleib Daimler for the first time included a Roots supercharger in a car engine

which improved the output of the engine. This was the first step towards its development.

94. DIAGRAMATIC ILLUSTRATION

ROOT SUPERCHARGER

(Fig-4.1)

TWIN-SCREW SUPERCHARGER

(Fig-4.2)

10CENTRIFUGAL SUPERCHARGER

(Fig-4.3)

115. DRIVES USED IN SUPERCHARGERS

Drives are basically the equipments that are used to transfer power from one shaft to another

shaft. In a supercharger, drives are used to transfer part of engine power to the supercharger

There are several types of drives used to empower a supercharger. These drives are used

according to there requirements.

Some of them are as under:

Mechanical:-

Belt (V belt, toothed belt & Flat belt).

Gear drive.

Chain drive.

Exhaust gas turbines:-

Axial turbine.

Radial turbine.

Other:-

Electric motor.

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6. SUPERCHARGERAN

EDGE OVER TURBOCHARGER

Superchargers do not suffer lag: - Superchargers have no lag time because they are driven

directly by the crankshaft, whereas Turbochargers suffers lag because it takes a few moments

before the exhaust gases reach a velocity that is sufficient to drive the impeller/turbine.

Since the superchargers are directly empowered from the engine, so as the engine starts, the

superchargers can be activated. But in the case of turbochargers they take some time for the

accumulation of exhaust gases.

Modification of the exhaust system: - Installing a turbocharger requires extensive

modification of the exhaust system, but superchargers can be bolted to the top or side of the

engine, that makes them cheaper to install and easier to service and maintain.

So this becomes a problem in the case of turbochargers. It becomes a tough task to modify

the exhaust system as well as it adds an extra cost in the vehicle.

Shutdown procedure: - No special shutdown procedure is required with superchargers as

they are not lubricated by engine oil. They can be shut down normally. Whereas

turbochargers must idle for about 30 seconds or so prior to shutdown so the lubricating oil

has a chance to cool down.

Thus it creates a problem during shutdown procedure as turbochargers can’t be shutdown

normally.

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7. NOTHING IS PERFECT

It derives power from the engine itself: Crankshaft drives superchargers so they steal some

of the engine's horsepower. A supercharger can consume as much as 20 percent of an

engine's total power output. So it can be considered as a loss of engine power.

(But because a supercharger can generate as much as 46 percent additional horsepower, I

think the trade-off is worth it).

Whereas this is not the case in turbochargers, it empowers itself from the exhaust gas of the

engine, which is mainly a waste of the engine.

An added strain on the engine: Supercharging puts an added strain on the engine, which

needs to be strong to handle the extra boost and bigger explosions. Engine and the other

connected mechanisms have to be made robust enough to bear the extra pressure. So this

makes the design engineer task tougher.

An extra expense: Heavy-duty components, design complexity & maintenance add an extra

burden on the expenses. And these expenses have to be made for better performance without

any compromise.

Though this seems too much, but when compared to its output, this seems a good deal.

148. CONCLUSION

Despite their disadvantages, superchargers are still the most cost-effective way to increase

horsepower.

Superchargers can result in power increase of 50 to 100 percent, making them great for

racing, towing heavy loads or just adding excitement to the typical driving experience.

It is a must use component in an airplanes.

As superchargers ensure complete combustion, it greatly reduces the pollution problem.

With the use of high octane premium-grade gas, I think it is a miracle invention for speed

junkies.

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REFERENCES

http://auto.howstuffworks.com/supercharger5.htm

http://www.howstuffworks.com/search.php?terms=supercharger

http://www.superchargerpros.com/

http://en.wikipedia.org/wiki/Supercharger

http://en.wikipedia.org/wiki/Supercharger#History

http://www.magnusonproducts.com/

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