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PRESENTED BY: VAIBHAV PATHAK ATMOSPHERIC JET ENGINE 02/14/2022 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR
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Atmospheric jet engines

Apr 21, 2017

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Engineering

Vaibhav Pathak
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Page 1: Atmospheric jet engines

05/02/2023 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

PRESENTED BY:VAIBHAV PATHAK

ATMOSPHERIC JET ENGINE

Page 2: Atmospheric jet engines

05/02/2023 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

INTRODUCTIONAn atmospheric jet engine is a reaction engine discharging a fast-moving jet that generates thrust by jet propulsion. It depends on the atmosphere for their supply of oxidant(air).Its working is based on two fundamental laws : Newton’s Second law of motion Newton’s third law of motion.

MATERIALS:Since a jet engine is subjected to a considerable amount of both mechanical and thermal stresses, therefore it is of extreme importance to use high strength and heat resistant materials to withstand these extreme conditions.COLD SECTION: Titanium alloys are used( intake )HOT SECTION: Nickel based super alloys are preferred(combustor, turbine, nozzle etc.)

Page 3: Atmospheric jet engines

05/02/2023 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

Turbojets are the oldest and most general purpose jet engines, finding use in a large variety of applications. They are most efficient at supersonic velocities, and are capable of speeds around Mach 3. They were also found on the Concorde and the Tupolev Tu-144.

A turbofan is essentially a turbojet but with a large ducted fan that provides additional thrust by moving large amount of low velocity air around the main engine. This type of engine is more efficient than turbojets at subsonic speeds. Ex. Boeing 747.

A ramjet is nothing more than a turbojet with all of the rotating parts removed. Ramjets are primarily used with missiles, dueto their simple, small, and high-velocity design

A scramjet is identical to a ramjet, but with one difference: combustion occurs with the air moving at supersonic velocities. As a result, scramjets are estimated not to work well below Mach 5, but could possibly reach speeds of Mach 24 (18000 mph).

TYPES OF ATMOSPHERIC JET ENGINESTURBOJET TURBOFAN RAMJET SCRAMJET

Page 4: Atmospheric jet engines

05/02/2023 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

Jet engines generate thrust through an application of Newton’s Third Law: An equal and opposite force is applied to the engine by the expulsion of a high velocity exhaust jet. The net force generated can be approximately described by the equation

where: = is weight flow rate of the air passing through the engine. = jet stream velocity = static pressure across propelling nozzle = atmospheric pressure = propelling nozzle area = aircraft speed

THRUST GENERATION

Page 5: Atmospheric jet engines

05/02/2023 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

The application of a TBC to turbine blades in jet engines has many significant advantages. By acting as a thermal shield, it allows a higher combustion temperature which improves engine efficiency and performance. Also, since the blades aren’t directly exposed to as high of a temperature, their service life increases while chance of catastrophic failure decreases.

IMPORTANCE OF THERMAL BARRIER COATING

Page 6: Atmospheric jet engines

05/02/2023 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

Higher combustion temperature – the hotter the fuel mixture is burned, the more thermodynamically efficient the engine becomes.

Better aerodynamic design – designing the engine to move air as efficiently as possible will increase both performance and reliability. Proper aerodynamic design is important for the turbine and compressor blades, as well as for the nozzle and intake system.

Increase pressure ratio – a large ratio between combustion and ambient pressure will allow fuel to burn more efficiently. Ratios of about 20-35 are common.

FACTORS AFFECTING ITS EFFICIENCY

Page 7: Atmospheric jet engines

05/02/2023 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

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