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

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AE 2304PROPULSION-IIpreparedByMr. Suresh
Chandra Khandai
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UNIT-I

• 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

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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.

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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.

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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

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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.

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• 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.

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• 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.

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• 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.

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UNIT-II

• 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

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RAMJET ENGINE
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SCRAMJET
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UNIT-III

• FUNDAMENTALS OF ROCKET PROPULSION
• 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

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SOLID PROPELLANT ROCKET MOTOR
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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.

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• The length of burn time is determined by the
  grain 'web thickness'.
• The grain may or may not be bonded to the casing.
  Case-bonded motors are much more difficult to
  design, since the deformation, under operating
  conditions, of the case and the grain must be
  compatible.

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UNIT-IV

• 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

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LIQUID ROCKET MOTOR
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UNIT-V

• ADVANCED PROPULSION TECHNIQUES
• Electric rocket propulsion
• Ion propulsion techniques
• Nuclear rocket
• Solar sail
• Concepts in nozzleless propulsion
• Numerical problems
• University question paper solution
• Revision

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Electric rocket propulsion

• ELECTRO THERMAL
• ELECTRO MAGNETIC(PLASMA THRUSTERS)
• ELECTRO STATIC(ION PROPULSION

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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.

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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.

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Nuclear Rocket

• Nuclear energy is used as propellant.

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Solar sail
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NOZZLELESS PROPULSION
Nozzleless solid propellant rocket motor
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THE END