Turbo Engines

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GAS TURBINE

http://en.wikipedia.org/wiki/File:GE_H_series_Gas_Turbine.jpg



INTRODUCTION

The earliest patent on gas turbine was that of the Englishman, John Barber, in year 1879.

Early designs were unsuccessful due tosome factors.

Serious development of the gas turbinebegan only after the second world war withthe shaft power in mind.

http://en.wikipedia.org/wiki/File:GE_H_series_Gas_Turbine.jpg



WORKING CYCLE:

BRAYTON CYCLE

Process 1-2:

Isentropic compression in the compressor Process 2-3:

Addition of heat at constant pressureProcess 3-4:

Isentropic expansion of air Process 4-1:

Rejection of heat at constant pressure



HOW DOES GAS TURBINE WORKS?

Gas turbine functions in the same way as theCompressed Ignition Engine. It sucks in air

from the atmosphere, compresses it.

The fuel is injected and ignited. The gases

expand doing work and finally exhausts

outside.

The only difference is instead of the

reciprocating motion, gas turbine uses a

rotary motion throughout.



THE THREE MAIN SECTIONS OF THE GAS

TURBINE

1. Compressor

2. Combuster

3. Turbine



BASIC COMPONENTS



1. COMPRESSOR

The compressor sucks the air from the atmosphere

and compresses it and guides it to the combustion

chamber.



2. COMBUSTER

This is an annular chamber where the fuel burns and

is similar to the furnace in a boiler. The air from the

compressor is the Combustion air.



3. TURBINE

Stationary guide vanes of turbine direct the gases

to the next set of blades. The kinetic energy of the

hot gases impacting on the blades rotates the

blades and the shaft.



Actual view of gas turbine



CLASSIFICATION OF GAS TURBINES

A. On basis of combustion process:1. Continuous combustion or Constant pressure

type

2. The explosion or constant volume type

B. On basis of path of working substance:1. Open cycle gas turbine

2. Closed cycle gas turbine

C. On basis of action of expanding gases:

1. Impluse turbine

2. Impulse- Reaction turbine

D. On the basis of direction of flow:

1. Axial flow

2. Radial flow



OPEN CYCLE GAS TURBINE

Fresh air is drawn into thecompressor from atmosphere.

Heat is added by combustionof fuel.

Exhaust from turbine isreleased in atmosphere.

Arrangement of continuousreplacement of workingmedium is required.



CLOSED CYCLE GAS TURBINE

In this , cycle is closed and

exhaust is not open toatmosphere.

In this there is continuously

supply of same working gas.

Higher density gases like

hydrogen or carbon dioxide

is used.

So we get higher efficiency

then open cycle GT.



Applications

Turbojet engines

Marine field

Supercharging

Railway engines

Generation of electricpower

Industry

Applications

http://en.wikipedia.org/wiki/File:LaudaNiki19760731Ferrari312T2.jpg



APPLICATION IN AIRCRAFT

Nearly all the military aircrafts are powered by gas turbine.

These are used for the higher generation of power in plane.



As there is cut off the auxilliary engine gas turbine gets

started.

As the speed of the plane increases the compressor gets

rotated and compresses the air and that get combusted incombustion chamber.

Then the exhaust gases are thrown out.



Working of Gas Turbine



ADVANTAGES

Very high power-to-weight ratio, compared toreciprocating engines.

Smaller than most reciprocating engines of the

same power rating.

Fewer moving parts than reciprocating engines

Low operating pressures & High operation speeds.

Low lubricating oil cost and consumption.

http://en.wikipedia.org/wiki/Power-to-weight_ratio








DISADVANTAGES

Higher Cost.

Less efficient than reciprocating engines at

idle.

Longer startup than reciprocating engines.

Less responsive to changes in power demand compared to reciprocatingengines.

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Turbo Engines