Chapter 3 Components of Gas Turbine Engine

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Ch3 Components of Gas Turbine Engine 3.1 Intake1. Subsonic intake 2. Supersonic intake

3.2 Compressor1. Compressor types and structures 2. Basic equations 3. Axial compressor 4. Centrifugal compressor 5. Compressor characteristics2

Ch3 Components of Gas Turbine Engine 3.3 Combustion chamber1. Specifications 2. Structures 3. Main process and main parts 4. Combustion characteristics

3.4 Turbine1. Structures 2. Principle 3. Characteristics3

Ch3 Components of Gas Turbine Engine 3.5 Afterburner1. Requirement 2. Working process and main parts

3.6 Nozzle1. Principle 2. Structure

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3.1 Intake

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3.1 Intake Intake is necessary Engine requires inlet axial speed less than M=0.7, however, the airplane can fly at M>1 in design condition. In off-design condition, engine inlet M and flying M are different. Need an intake to reduce speed and increase pressure to adapt to the engine.

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3.1 Intake Intake is a component of the engine even if though it is a structural part of the airplane. Engine factory does not make it.

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Total pressure recovery Inlet efficiency Total pressure recovery coefficient i : p1*= i p0* It will influence mass flow in the engine because mass flow is proportional to p1* (Inlet total pressure) 8

Total pressure recovery It also influence cycle thermal efficiency. According to calculation, if compressor inlet total pressure loses 1%, Thrust will lose more than 1.25%. In addition, if intake low efficiency could increase temperature at the section of before turbine, T3*.9

Stability Intake stability and uniform outlet flow (Distortion). Stability problem can introduce intake surge, cut combustion or break mechanical parts. Distortion can decrease compressor efficiency and lead engine into surge.

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Drag Intake can create additional drag forces: In supersonic flying, if shockwave does not touch the edge

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Drag Intake can create additional drag forces: Intake edge accelerate brutally external air flow to separation or supersonic

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Intake forms Suspended under wings, for subsonic airplanes Fighter Any configuration possible Front Lateral Under Up13

Intake forms Front intakesMig19, Mig21 Lateral intakes Radar and other electronic devices can be installed in the conic head of the plane. And pilots have a better view. Curve intakes can reduce reflection of radar waves, better for stealth. Problems: Losses, local separation. Especially, the airplane is doing maneuver and attack angle change can make the intake unstable and non-uniform of engine compressor inlet.14

Subsonic and supersonic intake Intakes form depends on flying speed. Pitot tube intake, subsonic intake, works for M