AMT-2203-Prelim-Learning-Module-01

Overview of Reciprocating Engine and Gas Turbine Engine

Introduction to Engines

  • Aircraft engines (powerplants) provide thrust necessary for aircraft propulsion.

  • Two main types of engines:

    • Reciprocating Engines: Work with propellers to produce thrust.

    • Gas Turbine Engines: Generate thrust through increased airflow velocity.

  • Engines also power aircraft systems for operation.

Learning Outcomes

  • Develop effective communication regarding reciprocating and gas turbine engines.

  • Understand techniques for safe aircraft engine operation and maintenance.

  • Identify and recall components and structures of both types of engines.

Reciprocating Engine

Design and Construction

  • Major components: crankcase, cylinders, pistons, connecting rods, valves.

  • Crankcase serves as the engine's foundation and houses various mechanisms.

  • Crankshaft transforms linear motion into rotary motion.

Crankcase Functions

  1. Self-supporting structure.

  2. Houses crankshaft bearings.

  3. Encloses lubricating oil.

  4. Supports internal and external powerplant mechanisms.

  5. Provides airplane attachment points.

  6. Supports cylinder attachments.

  7. Prevents crankshaft misalignment.

Types of Bearings

  • Plain Bearings: Primarily take radial loads; used in low-power engines.

  • Roller Bearings: Reduce friction; suitable for high-power engines.

  • Ball Bearings: Minimize rolling friction; resistant to both thrust and radial loads.

Crankshaft

  • Backbone of the reciprocating engine.

  • Components: main journal, crankpin, crank cheek, counterweights.

  • Crankshaft balancing is essential to minimize vibrations.

Connecting Rod

  • Transmits forces between piston and crankshaft.

  • Lightweight and strong to handle dynamic forces.

Pistons

  • Move within cylindrical chambers, generating power.

  • Designed for minimal friction and maximum contact area for lubrication.

  • Typically include grooves for piston rings.

Piston Rings

  • Function: seal combustion chamber, control oil entry, dissipate heat.

  • Types include:

    • Compression Rings: Prevent gas escape.

    • Oil Rings: Control lubricant on cylinder walls.

Cylinders

  • Convert chemical energy from fuel into mechanical energy.

  • Must withstand internal pressures and dissipate heat effectively.

  • Usually made from high-strength, lightweight metals.

Cylinder Assembly Components

  1. Cylinder barrel with skirt.

  2. Cylinder head.

  3. Valve guides and rocker-arm supports.

  4. Spark plug locations and cooling fins.

Accessory Section

  • Houses necessary accessories and drives various engine functions:

    • Fuel pumps, vacuum pumps, oil pumps, tachometer generators, magnetos, starters.

    • Rotational drives for accessories are managed through gear systems.

Gas Turbine Engine

Design and Construction

  • Functions of gas turbine engines are separated into distinct sections:

    1. Air inlet

    2. Compressor section

    3. Combustion section

    4. Turbine section

    5. Exhaust section

    6. Accessory section

Air Inlet

  • Introduces air to the engine's compressor, shaped aerodynamically for smooth airflow.

Compressor Section

  • Function: To increase pressure and mass airflow to the combustion burners.

  • Secondary role includes supplying bleed-air for auxiliary systems.

Types of Compressors

  1. Centrifugal-flow Compressor: Simple design, high pressure rise.

  2. Axial-flow Compressor: Direct airflow, high peak efficiency, suitable for multi-stage compressions.

Combustion Section

  • Burns the fuel/air mixture to generate energy.

  • Components:

    • Casing

    • Inner liner

    • Fuel injection system

    • Ignition source

    • Fuel drainage system.

Types of Combustion Chambers

  1. Can Type: High resistance to warpage, limited efficiency in space utilization.

  2. Can-annular Type: Combines benefits of both can and annular types.

  3. Annular Type: Efficient but susceptible to warping.

Turbine Section

  • Extracts energy from high-speed gases after combustion to drive the compressor and/or other engine components.

  • Types of turbines include impulse and reaction turbines, with turbojet engines typically using reaction-impulse types.

Exhaust Section

  • Directs hot gases rearward, ensuring a high exit velocity.

  • Components include:

    • Exhaust cone (collects/distributes exhaust gases)

    • Tailpipe (supports thermal expansion)

    • Exhaust nozzle (critical for engine performance).

Exhaust Nozzle Types

  • Converging: For subsonic speeds.

  • Converging-diverging: For supersonic speeds; must adapt based on engine operation state.

Evaluation Activities

  • Identification and enumeration tasks related to components and functions discussed in the module.

Timeframe

  • Module completion should take approximately 9 hours.

Honesty Clause

  • Statement ensuring individual work and adherence to module guidelines.