Engines used in the earlier parts of 20th century had deficiencies in spite of their advantages. The advantages used in those times were Turboprop engines. These engines could produce only 10% of their thrust from the exhaust jet. They could not attain high speed.Tags : turbofan engine ppt,turbofan engine pdf,turbofan engine seminar,turboprop engine,turbojet engine,ramjet engine,turboshaft engine,turbofan vs turbojet
Researches were conducted further, which led to the developments of Turbofan engines. Turbofan engines combined the hot air jet with bypassed air from a fan. This created a quieter engine with greater boost at low speeds, making it a popular choice for commercial airplanes. And due to generation of more thrust for nearly the same amount of fuel, it is highly fuel-efficient
What is a Turbofan Engine?
A turbofan engine is the most modern variation of the basic gas turbine engine. As with other gas turbines, there is a core engine. In the turbofan engine, a fan in the front and an additional turbine at the rear surrounds the core engine. The fan and fan turbine are composed of many blades, like the core compressor and core turbine, and are connected to an additional shaft
As with the core compressor and turbine, some of the fan blades turn with the shaft and some blades remain stationary. The fan shaft passes through the core shaft for mechanical reasons. This type of arrangement is called a two-spool engine (one "spool" for the fan, one "spool" for the core.) Some advanced engines have additional spools for sections of the compressor, which provides for even higher compressor efficiency.
Jet Engine Thrust
The force produced by a jet engine is expressed in terms of kilograms of thrust. This is a measure of the mass or weight of air moved by an engine times the acceleration of the air as it goes through the engine. Technically, if the aircraft were to stand still and the pressure at the exit plane of the jet engine was the same as the atmospheric pressure, the formula for the jet engine thrust would be:
Weight of air in kilograms per second * velocity
Thrust = ___________________________________________
9.81 (normal acceleration due to gravity, in meter per second 2)
Imagine an aircraft standing still, capable of handling 97.522 kilograms of air per second. Assume the velocity of the exhaust gases to be 1,500 feet per second. The thrust would then be:
Thrust = 97.522 kg of air per second * 457.2 m / s
9.81 m / s 2
= 9.941 * 457.2
Thrust = 4545.025 kg.
If the pressure at the exit plane is not the same as the atmospheric pressure and the aircraft were not standing still, the formula would be somewhat different
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