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Turbojet engine

By : Asad Ali Arshad
Turbo Jet Engine
The turbojet is an air breathing jet engine, typically used in aircraft of a gas turbine with a propelling nozzle. The gas turbine has an air inlet, a combustion chamber and a turbine. The compressed air from the compressed is heated by the fuel in the combustion chamber and then allowed to expand through the turbine. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high.
It works on the basis of Newton’s third law of motion which stated that “action and reaction are equal in magnitude but opposite in direction”. The high speed thrust produce will act as action and in reaction the airplane moves in the forward direction.

Types of turbo Engines

·         Turbojet engine
·         Turbofan engine
·         Turbo propeller Engine
·         Ramjet Engine
·         Scramjet Engine
It works on the Brayton Cycle

Air Intake

The air is entered from the intake tube. It is subsonic air having low pressure and temperature which is then entered into the compressor.

Compressor

Compressor squeezes fresh air into engine. Initially the compressor ratio is 1:8 and nowadays the compressor can compress the air by 44:1. In the compressor the temperature and pressure of the air is increases.  After leaving the compressor air enters into the combustion chamber.

Combustion Chamber

The hot air from the compressor enters into the combustion chamber where it burns with the fuel and pass through the turbine continuously. The air-fuel mixture exhausted and produces high thrust which in reaction moves the airplane in the forward direction.

Turbines

Exhaust gases passes through the turbine rotating it like a wind mill. These are impulse turbine rotated because if the impact of the hot gas steam. Later stages are convergent ducts that accelerate the gas.





Afterburners

Afterburner is used in supersonic aircraft. It is a combustion chamber which is added to reheat the turbine exhaust gases. The fuel combustion is high typically four times more than that of the main engine.
 Merit and Demerits of turbojet engines are given below.

Merits

·         Compact them most reciprocating engine
·         Very high to power ratio
·         Low operating pressure
·         High operating speed
·         Low lubricating oil cost
·         Less parts





Demerits

·         High manufacturing cost.
·         Longer starter than reciprocating engine
·         Less response to changes in power demand compared to reciprocating engines.


Thermodynamics

By : Asad Ali Arshad
Thermodynamics Lecture no 5
Thermodynamics

Chapter no 5:   Mass Energy Analysis of Control Volume

chapter 5.pdf

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In this chapter we will discussed the following topics in detail:

  • Energy Analysis of Steady flow
  • First law of thermodynamics for a Control Volume under steady flow
  • Mass and Energy balance for a steady-flow Process
  • Some Steady flow Engineering Devices
  • Turbines and Compressor
  • Throttling value
  • Heat Exchanger




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