What component helps drive the engine fan in the described jet engine?

What component helps drive the engine fan in the described jet engine?

• A. Turbine blades attached to a shaft that runs up to the front of the engine and helps turn the fan.
• B. The compressor directly drives the fan.
• C. Electric motor powers the fan.
• D. Air pressure turns the fan.

Answer: (A)

In a turbofan jet engine, the fan is turned by mechanical power transmitted from the turbine. Hot, high-energy gases rotate turbine blades, and those turbines are connected to a shaft that runs forward to the front of the engine. This shaft powers the front fan (and the compressor) as it turns, so the energy from burning fuel ultimately drives the fan through that turbine-driven shaft. The compressor is likewise driven by the same shaft, but it’s the turbine that provides the energy, not the compressor driving the fan. An electric motor isn’t the usual power source for a conventional jet engine, and air pressure by itself doesn’t rotate the fan.

In a turbofan jet engine, the fan is turned by mechanical power transmitted from the turbine. Hot, high-energy gases rotate turbine blades, and those turbines are connected to a shaft that runs forward to the front of the engine. This shaft powers the front fan (and the compressor) as it turns, so the energy from burning fuel ultimately drives the fan through that turbine-driven shaft. The compressor is likewise driven by the same shaft, but it’s the turbine that provides the energy, not the compressor driving the fan. An electric motor isn’t the usual power source for a conventional jet engine, and air pressure by itself doesn’t rotate the fan.