Aerothermal Propulsion

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Aerothermal Propulsion

• Lecture 32
• Optimized Nozzle Design

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Talos Missile
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Agenda

• Nozzle efficiency
• Nozzle design

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Optimized Ramjet
Combustion chamber
nozzle
Inlet-diffuser
Supersonic compression
subsonic compression
Combustion
expansion
a
1.
2.
5.
3.
4.
7.
6.
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Real Thrust Equation
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Nozzle Design

• In general inlets like to de-accellerate air to
  the turbojet core or ramjet combustion region at
  M.4 or less
• The Combustion raises the M slightly, but the M
  lt1 so it must be brought up to the same M as
  entry inlets with minimum stagnation loss
  P06/P01
• This requires a nozzle to accelerate the air back
  up to MeMa

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Jet Engine Nozzles
Su-27 Flanker -thrust vectoring
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Jet Engine Nozzles
F100 Jet engine
Adjustable nozzles allow optimization
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Ramjet fixed nozzle
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Optimized Ramjet
Combustion chamber
nozzle
Inlet-diffuser
Supersonic compression
subsonic compression
Combustion
expansion
a
1.
2.
5.
3.
4.
7.
6.
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
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Nozzle Efficiency
Pressure Matching Condition
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Nozzle Efficiency
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Nozzle Efficiency
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Summary

• Inlets and diffusers slow down air so it can be
  combusted in turbine or ramjet cores
• Combustors in practice operate at M.4 for less
  to avoid combustion instability. Effective
  velocity is often M0 at ignition point
• Combustors must avoid thermal choking where M1
  in combustor
• Nozzles raise the mach number back to Ma by
  isentropic flow