Pratt&Whitney completes testing on F-135 engine with “three-stream” adaptive turbofan technology

[F-22Raptor]

Tests this year on an F135 core engine paired with an experimental fan module featuring adaptive bypass airflow to improve fuel efficient and cooling capacity “met or exceeded expectations”, says engine manufacturer Pratt & Whitney.

The testing on a full-scale powerplant for the Lockheed Martin F-35 wraps up P&W’s role under a four-year adaptive engine technology development (AETD) programme sponsored by the Air Force Research Laboratory (AFRL).

The testing was intended to understand the maturity of so-called “three-stream” adaptive turbofan technology as AFRL launches a $1 billion programme to develop a full-scale, 45,000lb-thrust-class prototype engine under the Adaptive Engine Transition Programme (AETP) that could be used to re-engine the F-35 and power a future combat aircraft.

“This is an important milestone on the path toward the advancement and maturation of a next generation adaptive engine which will enable the warfighter to stay well ahead of future and emerging threats,” says Matthew Bromberg, president of P&W Military Engines, in a news release.

The AFRL is using a competitive development approach for adaptive engine technology, supporting P&W and GE Aviation through the full-scale prototype stage in AETP.

With a goal to improve specific fuel consumption by 25% compared to a 2000-baseline combat aircraft engine US Air Force and Navy have been pursuing adaptive engine technology since 2006.

The adaptive engine is designed to improve efficiency by inserting a valve in the fan module that in cruise mode opens to permit a third stream of airflow – in addition to core flow and bypass flow. The third stream increases the volume of bypass flow to make the engine more efficient in producing thrust. It also creates a new heat-sink within the engine, which allows the designers to improve fuel efficiency by increasing temperatures inside the core.

https://www.flightglobal.com/news/a...esting-on-f135-engine-with-adaptive-f-441230/

 

[F-22Raptor]

Here's more info on the engine:

Modern military turbofan engines have two airstreams – one that passes through the core of the engine, and another that bypasses the core. The development of a third stream provides an extra source of air flow to improve propulsive efficiency and lower fuel burn, or to deliver additional air flow through the core for higher thrust and cooling air. Utilizing a third stream of air that can be modulated to adapt the engine's performance across the flight envelope means a fighter can have the best of both worlds by accessing an on-demand increase in thrust or smoothly shift to highly efficient operations during cruise. This capability provides an optimal balance for combat scenarios requiring both high-end acceleration and increased range.

The adaptive three-stream fan technology leverages and improves upon Pratt & Whitney's experience as the only provider of fifth generation fighter engines – the F119 and F135, which power the F-22 Raptor and F-35 Lightning II, respectively.

While Pratt & Whitney is demonstrating the efficacy of a three-stream architecture under AETD, it is also maturing other advanced propulsion technologies considered essential for high-speed and long-endurance performance requirements. This includes adaptive control systems as well as improved integrated power and thermal management capacity which can enable more sensors, data fusion, electronic warfare, and directed energy. The goal of the AETD program is to provide a 25 percent reduction in fuel consumption and a 10 percent improvement in thrust levels compared to today's fifth-generation combat aircraft engines.

http://www.prnewswire.com/news-rele...reakthroughs-with-latest-tests-300520985.html

P&W are truly ahead of the game!

 

[Gomig-21]

Modern military turbofan engines have two airstreams – one that passes through the core of the engine, and another that bypasses the core. The development of a third stream provides an extra source of air flow to improve propulsive efficiency and lower fuel burn, or to deliver additional air flow through the core for higher thrust and cooling air. Utilizing a third stream of air that can be modulated to adapt the engine's performance across the flight envelope means a fighter can have the best of both worlds by accessing an on-demand increase in thrust or smoothly shift to highly efficient operations during cruise. This capability provides an optimal balance for combat scenarios requiring both high-end acceleration and increased range.

Sounds like those airstream ducts and passages and bypasses are what allow these engines to perform supercruise, along with other functions of the aircraft's aerodynamic design, I'm sure. US tech is on another level. Supercruise has revolutionized the efficiency of these engines.

Although I must say, watching Russian engines suspend huge aircraft such as the Su-35 in mid-air and allowing them to spin and twist and hover without losing altitude or stall is also very impressive. The thrust produced by those engines is really outstanding. Efficiency, on the other hand, might be a bit questionable but still, to provide that kind of sustained energy without compromising the aircraft is something to admire and credit as well.

I also find it pretty interesting how the Russians have put a lot of emphasis on thrust vector control, while the US has only utilized that innovation to a certain extent in the Raptor and to some degree in the F-35B. Interesting comparison in the two schools of thought.

 

[Sinnerman108]

Sounds like those airstream ducts and passages and bypasses are what allow these engines to perform supercruise, along with other functions of the aircraft's aerodynamic design, I'm sure. US tech is on another level. Supercruise has revolutionized the efficiency of these engines.

Although I must say, watching Russian engines suspend huge aircraft such as the Su-35 in mid-air and allowing them to spin and twist and hover without losing altitude or stall is also very impressive. The thrust produced by those engines is really outstanding. Efficiency, on the other hand, might be a bit questionable but still, to provide that kind of sustained energy without compromising the aircraft is something to admire and credit as well.

I also find it pretty interesting how the Russians have put a lot of emphasis on thrust vector control, while the US has only utilized that innovation to a certain extent in the Raptor and to some degree in the F-35B. Interesting comparison in the two schools of thought.

Jet Engines technology is complicated, and the most problematic area is the turbine stage, NOT the compressor stage.

The problem is to have the turbine sustain 2700C plus temperature for long times.

As of now we have technology to compress a lot more air, and fuel which can give us a lot more energy;
what we do not have is materials to be put in the turbines to transfer that energy back in the energy cycle. Thus we compromise those advantages.

Usual jets burn fuel ( After burners) after the turbine stage to get to supersonic speeds.
If durable turbines can be made, then supercruise is sustainable without after burners.

Russian engines have low life because they punch their engines, whereas the west stays safe in the operational parameters.

 

[Gomig-21]

If durable turbines can be made, then supercruise is sustainable without after burners.

No sure what you mean by that. They're already achieving supercruise with the current F-119 and F-135. When the aircraft reaches close to mach 1, the compressor bypass is reduced to allow more air into the combustion chamber and by adding more fuel at the same time, it increases thrust which burns much less fuel than if it's added at the afterbrner stage.

The lower the airspeed, the higher the bypass to allow the turbofans to increase thrust with less fuel. The higher the airspeed, the less bypass which allows more air in the combustion chamber mixed with more fuel to increase thrust which basically achieves supercruise that is much more efficient than if it was created using afterburner, which burns nearly 30 times more fuel than the average jet's cruising fuel flow.

Now they're talking about creating a 3rd bypass stage to create a sort of variable bypass ratio to increase that efficiency even more at supercruise. Unless I misunderstood.