Supercharger Report

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 by

SUSHANT KUMAR REGD NO:1201229282

Under the Guidance of Asst. prof. Rashmi Ranjan Senapati ( Department of Mechanical Engineering)

DEPARTMENT OF MECHANICAL ENGINEERING DRIEMS, CUTTACK, ODISHA

November- 2015 CERTIFICATE 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 (Seminar guide)

Asst. Prof. Sonali Rath (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 kumar Department 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 4.3 Centrifugal supercharger

10 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) 1

1.1 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.

2

1.2 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) 3

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) 4

3. 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) 7

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, highpressure 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)

8

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.

9

4. DIAGRAMATIC ILLUSTRATION

ROOT SUPERCHARGER

(Fig-4.1)

TWIN-SCREW SUPERCHARGER

(Fig-4.2)

10

CENTRIFUGAL SUPERCHARGER

(Fig-4.3)

11

5. 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.

12

6. SUPERCHARGER AN 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.

13

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.

14

8. 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.

15

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/

16