CFM56-7B Turbofan Engine Overview

Introduction

• Purpose: Create thrust for aircraft movement by accelerating air from front to back of the engine.

Key Components of the CFM56-7B

1. Fan

   • Large diameter propeller that accelerates air.

2. Compressors

   • Low Pressure Compressor:
     • Step-by-step pressure increase, consisting of 12 stages.
   • High Pressure Compressor:
     • Works in tandem with low pressure compressor to further increase air pressure.

3. Combustion Chamber

   • Location where jet fuel is mixed with compressed air and ignited.

4. Turbines

   • High Pressure Turbine:
     • 1 stage, helps drive the high-pressure compressor.
   • Low Pressure Turbines:
     • 4 stages, help drive the low-pressure compressor and fan.

5. Exhaust Assembly

   • Final component where exhaust gases exit the engine.

Engine Functionality

• High Bypass Ratio Engine:
  • 80% of airflow goes through the bypass duct, providing 80% of the engine thrust.
  • Primary flow passes through compressors, combustor, and turbines; secondary flow is directed by the fan.

Airflow Process

1. Compression:

   • Air is compressed in both low and high-pressure compressors.
   • Temperature can reach up to 450°C.

2. Combustion:

   • Heated air enters combustor where fuel is injected and ignited, raising temperature to 1700°C.

3. Energy Extraction:

   • Hot gases pass through five turbine stages, extracting energy and reducing pressure.
   • Turbines drive the compressors and fan.

4. Exhaust:

   • Air expelled through primary duct, combining with air from the fan stream.

Summary

• A turbofan engine operates on a flow cycle:
  • Air is compressed → Heated by burning fuel → Passed through turbines → Drives compressors and fan.