Transcript AE 2304 PROPULSION-II By Mr.Suresh Chandra Khandai

AE 2304
PROPULSION-II
prepared
By
Mr. Suresh Chandra Khandai
UNIT-I
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AIRCRAFT GAS TURBINES
Impulse and reaction blading of gas turbines
Velocity triangles and power output
Vortex theory
Choice of blade profile, pitch and chord
Estimation of stage performance
Limiting factors in gas turbine design
Methods of blade cooling
Matching of turbine and compressor.
Numerical problems
University question paper solution
Gas Turbines
• Work can be extracted from a gas at higher
inlet pressure to the lower back pressure by
allowing it to flow through the turbine.
• The work done by the gas is equivalent to the
change of its enthalpy.
Impulse turbines
 An impulse stage is characterized by the expansion of the gas
which occurs only in the stator nozzles.
 The rotor blades act as directional vanes to deflect the
direction of the flow.
 They convert the K.E. of the gas into work by changing the
momentum of the gas more or less at constant pressure.
Reaction turbines
• A reaction stage is one in which expansion of the gas takes
place both in the stator & in the rotor.
• The function of the stator is the same as that of the impulse
stage, but the function of the rotor is in two folds
Methods of blade cooling
• Convection cooling works by passing cooling air through
passages internal to the blade. Heat is transferred by
conduction through the blade, and then by convection into
the air flowing inside of the blade. A large internal surface
area is desirable for this method, so the cooling paths tend to
be serpentine and full of small fins.[
• A variation of convection cooling, impingement cooling,
works by hitting the inner surface of the blade with high
velocity air. This allows more heat to be transferred by
convection than regular convection cooling does.
Impingement cooling is often used on certain areas of a
turbine blade, like the leading edge, with standard convection
cooling used in the rest of the blade.
• The second major type of cooling is film cooling . This type of
cooling works by pumping cool air out of the blade through
small holes in the blade. This air creates a thin layer (the film)
of cool air on the surface of the blade, protecting it from the
high temperature air. The air holes can be in many different
blade locations, but they are most often along the leading
edge.
• Transpiration cooling, the third major type of cooling, is
similar to film cooling in that it creates a thin film of cooling
air on the blade, but it is different in that that air is "leaked"
through a porous shell rather than injected through holes.
This type of cooling is effective at high temperatures as it
uniformly covers the entire blade with cool air.
• Transpiration-cooled blades generally consist of a rigid strut
with a porous shell. Air flows through internal channels of the
strut and then passes through the porous shell to cool the
blade.
UNIT-II
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RAMJET PROPULSION
Operating principle of Ram jet engine
Sub critical, critical and supercritical operation of Ramjet
Combustion in Ramjet engine
Ramjet performance
Ramjet design calculations
Introduction to scramjet.
Numerical Problems
University question paper solution
RAMJET ENGINE
SCRAMJET
UNIT-III
FUNDAMENTALS OF ROCKET PROPULSION
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Operating principle
Specific impulse of a rocket - Derivation
Internal ballistics of rocket engines
Rocket nozzle classification - Explanation
Rocket performance considerations
Numerical problems
University question paper solution
SOLID PROPELLANT ROCKET MOTOR
DESIGN
• Design begins with the total impulse required, which
determines the fuel/oxidizer mass. Grain geometry and
chemistry are then chosen to satisfy the required motor
characteristics.
• The following are chosen or solved simultaneously. The results
are exact dimensions for grain, nozzle, and case geometries.
• The grain burns at a predictable rate, given its surface area
and chamber pressure.
• The chamber pressure is determined by the nozzle orifice
diameter and grain burn rate.
• Allowable chamber pressure is a function of casing design.
• The length of burn time is determined by the grain 'web
thickness'.
• The grain may or may not be bonded to the casing. Casebonded motors are much more difficult to design, since the
deformation, under operating conditions, of the case and the
grain must be compatible.
UNIT-IV
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CHEMICAL ROCKETS
Solid propellant rockets – Selection criteria of solid
propellants
Hardware components of solid rockets – Propellant grain
design considerations
Liquid propellant rockets – Selection of liquid propellants
Cooling in liquid rockets
Hybrid rockets
Numerical problems
University question paper solution
LIQUID ROCKET MOTOR
UNIT-V
ADVANCED PROPULSION TECHNIQUES
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Electric rocket propulsion
Ion propulsion techniques
Nuclear rocket
Solar sail
Concepts in nozzleless propulsion
Numerical problems
University question paper solution
Revision
Electric rocket propulsion
• ELECTRO THERMAL
• ELECTRO MAGNETIC(PLASMA THRUSTERS)
• ELECTRO STATIC(ION PROPULSION
ELECTRO THERMAL PROPULSION
Electro-thermal propulsion systems are those systems in which
electrical energy is used to heat propellants, thus producing
thrust.
Principle
Electro-thermal systems heat propellants , which produce
gases. The gases are then sent through a supersonic nozzle
to produce thrust.
Ion propulsion Technique
• This technique of propulsion utilizes
electrostatic energy, i.e. energy due to
electric charges on materials is used to propel
rockets. Since ions are used for this, the
technique is also called as ion propulsion
technique.
Nuclear Rocket
• Nuclear energy is used as propellant.
Solar sail
NOZZLELESS PROPULSION
Nozzleless solid propellant rocket motor
THE END