Image Credit:GE Aviation US Air Force Research Laboratory (AFRL) and General Electric Aviation is developing a sixth generation hig...
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Image Credit:GE Aviation
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The new engine design called ADVENT (Adaptive Versatile Engine Technology), can switch between high power and high efficiency modes, operating effectively and efficiently over a wide range of flight conditions, from subsonic to supersonic speeds.
Present fighter jets use sleek and narrow supersonic engines called low-bypass turbofans to generate enormous thrust by compromising fuel efficiency. They are called low bypass because over 90 percent engine air inlet goes through the engine core. However commercial passenger jets use bigger high-bypass turbofans, which are fuel efficient and low noise due to high bypassing of inlet air.
The ADVENT engine combines both the high bypass and low bypass architecture into one , through a innovative architecture that shifts air flow between the core, the main bypass, and a third stream to achieve thrust, optimal performance, and fuel efficiency.
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| Animation showing GE ADVENT switching between high bypass and low bypass engine |
One of the key technologies behind the adaptive-cycle engine is the adaptive fan, which allows the engine to vary its bypass ratio depending on its altitude and speed.
At cruising speeds, the third air intake pathway is used to increase the amount of bypass air around the engine’s core, which boosts propulsive efficiency.
The Adaptive Engine program aims to achieve a 25 percent fuel efficiency improvement with the extra fuel enough to provide a 30 percent increase in operating range, and a five-to-ten percent improvement in thrust compared to today's fixed-cycle engines.
The idea dates back to the 1960s, when German jet engine pioneer Gerhard Neumann realized that he could manage jet engine performance by controlling the amount of air that flows through the engine core. More flow yields more thrust and speed (that’s good for fighter jets); less flow saves fuel.
The new adaptive cycle engine is building on the YF120, GE’s first variable cycle engine prototype built and flight tested in the 1990s. The engine lost to what became the Pratt & Whitney F119 that powers the Lockheed Martin F-22 Raptor.
USAF selected GE for the ADVENT program in 2012. GE began testing the ADVENT demonstrator engine in November 2013, six years after development began in 2007.
The team last year achieved the highest temperature ever recorded inside a jet engine core, surpassing engine target temperatures by more than 130 degrees Fahrenheit. To take the heat, GE has developed new heat resistant materials called ceramic matrix composites(CMCs).
The AFRL’s follow-on Adaptive Engine Technology Development (AETD) program is intended to bring the technologies developed under ADVENT into a flight-worthy design.
The AETD program will build off these and other demonstrations to mature these technologies in preparation for eventual low-risk transition into combat aircraft in the 2020 timeframe.
GE will continue to mature the ADVENT technologies through the AETD program, which will conclude in 2016 following fan rig testing and a core engine test.
Pratt & Whitney's AETD program will lead to demonstration testing of an advanced high-pressure ratio core in early 2016, to be followed later in 2016 by full engine testing of a three-stream adaptive fan and three-stream compatible augmentor and exhaust system.
Major benefit of the adaptive cycle engine will be the reduced demand for deployed fuel and tanker aircraft support, hence reducing operational cost.
While US Air Force has its ADVENT, AETD and NextGen programs to develop next generation engine technology, the Navy has its Variable Cycle Advanced Technology (VCAT) program looking to adapt these technology for naval aviation.
