Paper Example - Development and Advantages of Geared Turbofan Engine

The Geared Turbofan engine technology has been adopted by Pratt & Whitney in their PW1000G Pure Power Engine development to create a lightweight solution, with increased efficiency, lower noise, and optimal economy for their passenger aircraft. Pratt & Whitney has been developing the Geared Turbofan engine technology since 2008 while planning to implement it in 2012 (Transportation, 2007) fully. The development of the GTF entails mounting a hub gearing system which serves the purpose of running the engine fan mounted at the front of the engine at a quite lower speed than conventional turbofan jet at 16% lower fuel burning and at 15 to 20db lesser than required regulations (Langston, 2013). The first generation GTF development of P&W utilized 3:1 of gear reduction, which translated into a bypass ratio of 12:1.

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The development of the GTF involves creating separate-gear connected shafts which serve the purpose of running the fan separately from the turbine spool and the compressor. The separation makes the various components operate at a different speed but their optimal speeds. The mounted reduction gear is uniquely installed with an epi-cyclic gear train for the fan, while the shaft likening the compressor to the engine is connected with a sun-shaped gear. The sun gear is reconnected to mesh and function with other adjacent five gears held by a carrier and operates by meshing with the fan gear (Langston, 2013). Since the gearbox adds weight to the engine, the weight is compensated by getting rid of the engine core components.

The primary characteristic feature of a geared turbofan is the existence of a reduction gearbox placed the engines fan and the separate low-pressure turbine to serve the purpose of allowing the fan to attain various rotation speeds that vary from the turbine and compressor low pressure. The geared turbofan is unique because the geared box addition makes the speeds of all the engine components to be optimized as high as possible for the low speed and pressure of the turbine (Kurzke, 2009). Consequently, the enhanced speed capability of a geared turbo engine prompts less requirement of compressor and turbine stages. The need for fewer engine components makes the engine core smaller in size and of lesser weight. The conventional turbofan engine is an engine characterized by thrusting emanating from the jet core efflux and ducted bypass air sourced from a fan driven by the jet core. Thus, in the development of the geared turbofan engine, a reduction geared box in installed in the turbofan to make the fan have the capability of having adjustable, varying speeds and improve the efficiency of the turbo engine past a conventional turbo engine. Geared TF has a quite higher bypass ratio of as high as 11 or 12: 1, which translates into efficiency in fuel consumption compared to ungeared turbofan with a BPR of as low as 8:1 (Kupratis, & Schwarz, 2014).

The significant advantage of the geared turbos is the capability to make the fan rotate at various speeds different from the compressor and turbine speed, enabling each device to run at their optimal speeds. This makes the geared fan to have the capability of rotating at low rotational speeds, which increase efficiency by avoiding the high supersonic tip speeds (Kurzke, 2009). The development of the geared turbo engine has prompted jet engines to have a high thrust engine capability without adding components that increase the engine's weight and the jet. This advantage has been applied to power high large commercial aircraft since it offers a lightweight solution while enabling the jets to have high thrust levels. It has a few stages of LPC, HPC, and LPT, which contribute to the lightweight solution. The geared engine has additional bypass air advantage and menaced efficiency, which makes the geared engine to have lower fuel burn of as low as up to 15% lower fuel consumption (El-Sayed, 2008).

Consequently, the GTF has lower emission of fuel gases such as carbon dioxide and nitrous oxide compared to other jets such as the turbofan jet. According to Pratt & Whitney, developing a GTF for an aircraft of 70 to 150 passengers makes the jet engine to have been the fuel less and consequently lower the carbon dioxide emission by more than 12% (Transportation, 2007). The feature makes the GTF to run as a third of the turbine speed, enhancing the propulsive efficiency. Thus, the geared turbofan optimizes the benefits of turbofan of being quitter and efficient to increased propulsive efficiency on top of the turbofan advantages. Also, Pratt & Whitney assert that GTF technology makes them lower the noise levels at about 20dB lower than the aircraft stage 4 regulations. Pratt and Whitney planned to venture into the GFT technology installation in 2008 on the base that the GFT will offer an exceptional synergy of attaining low noise levels integrated with enhanced engine control capabilities (Transportation, 2007). Besides, the GTF has a high thermal efficiency compared to other turbo jets since the added reduction gearbox lowers its maximum cycle temperature.

References

El-Sayed, A. F. (2008). Aircraft propulsion and gas turbine engines. CRC press. https://www.amazon.com/Aircraft-Propulsion-Gas-Turbine-Engines/dp/0849391962

Kupratis, D. B., & Schwarz, F. M. (2014). U.S. Patent No. 8,887,487. Washington, DC: U.S. Patent and Trademark Office. https://books.google.co.ke/books?id=VwueCAAAQBAJ&pg=PA111&lpg=PA111&dq=Kupratis,+D.+B.,&source=bl&ots=LOFOVM4Zdc&sig=ACfU3U0mhWQ1odQs-yqPN22Z-sECJEVGwg&hl=en&sa=X&ved=2ahUKEwitz-7J67vqAhVR3IUKHaXSAzwQ6AEwAHoECAoQAQ#v=onepage&q=Kupratis%2C%20D.%20B.%2C&f=false

Kurzke, J. (2009, January). Fundamental differences between conventional and geared turbofans. In Turbo Expo: Power for Land, Sea, and Air. https://asmedigitalcollection.asme.org/GT/proceedings-abstract/GT2009/48821/145/344595

Langston, L. S. (2013). Not So Simple MachinesThe Geared Turbofan may be a Revolutionary Jet Engine, but it’s just the Latest Device to Employ Precision Gearing. Mechanical Engineering Magazine Select Articles. https://asmedigitalcollection.asme.org/memagazineselect/article-standard/135/01/30/472417/Not-So-Simple-MachinesThe-Geared-Turbofan-may-be-a

Transportation, U. C. (2007). Essential Air Service and Small Community Air Service Development Programs: Hearing Before the Subcommittee on Aviation of the Comm. on Transportation and Infrastructure, 110th Cong. https://www.transportation.gov/testimony/essential-air-service-program-and-small-community-air-service-development-program