it is about atmospheric jet engine, a very brief description in about 7 slides only with informative content and .gif images incorporated in it.

1. PRESENTED BY:
VAIBHAV PATHAK
ATMOSPHERIC JET ENGINE
4/15/2017 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

2. INTRODUCTION
An 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.)
4/15/2017 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

3. 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, due
to 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 ENGINES
TURBOJET TURBOFAN RAMJET SCRAMJET
4/15/2017 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

4. 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
4/15/2017 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

5. 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
4/15/2017 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

6.  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
4/15/2017 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR

7. THANK
YOU
4/15/2017 VAIBHAV PATHAK ,MECHANICAL , B.TECH 4TH YEAR