The Embraer 170/175 aircraft is powered by two General Electric CF34-8E turbofan engines designed for commercial service. Each engine is a high-bypass, dual rotor turbofan with independent N1 and N2 rotors.
The basic engine is comprised of multiple sections such as the Fan Case or the “cold section” of the engine: This comprises the fan rotor and stator assemblies, front frame, power takeoff, compressor rotor and stator, and combustion chamber frame. The fan rotor assembly is direct-drives and supplies most engine thrust.
Core Engine Module: This sits between the fan section and the low-pressure turbine, compressing exit air from the fan and supplying it to the combustor. It houses the combustion liner where combustion occurs, and the high-pressure turbine, which extracts power from hot gases.
Low-Pressure Turbine (LPT): Positioned behind the High-Pressure Turbine, it harnesses gases exiting the former, driving the shaft that turns the fan rotor.
Accessory Gearbox (AGB): Mechanically translates engine power to operate various components, including pumps and generators.
Fuel and Control System:
Manages and delivers fuel for combustion. The main pump ensures the right flow and pressure. Fuel is filtered to remove contaminants. The Fuel Metering Unit (FMU) accurately delivers fuel for combustion and other functionalities. The fuel manifold distributes fuel to 18 injectors that atomize it in the combustion chamber.
The thrust lever assembly in the cockpit schedules forward and reverse thrust. There are protective mechanisms to ensure the thrust lever doesn’t go below idle during flight.
Engine operations are overseen by a dual channel FADEC system, which controls various components and systems.
Engine Airflow Systems:
Control the volume of air through the compressor. Systems like the Variable Stator Vane help optimize airflow at varying engine conditions and improving efficiency.
Thrust Reverser Actuation System (TRAS):
Allows the redirection of fan air to achieve reverse thrust, mainly for braking after landing. This is controlled from the cockpit and is independent for each engine.
Engine Oil System:
Lubricates and cools engine and gearbox components. It uses an engine-driven pump to supply oil, which is filtered and cooled before use.
Engine Ignition System:
Initiates engine combustion through electrical sparks. This system detects engine flameouts and reignites when necessary.
Ensures the engine attains the needed rotor speed to start combustion. Components include an air turbine starter, bleed air system, and more. The starter accelerates the engine core to the necessary speed and provides both wet and dry motoring for maintenance.
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