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Glavni inzenjer RolsRojsa na temu buducih motora
Citat:A key focus area for R-R is the development of distortion-tolerant military fans, which are better able to deal with separation of air flow issues. Banks says the length of the intake in front of the engine is determined by fan-size. If the length is less than four times the fan diameter, "very, very high distortion levels" occur.
"What you want to do is crumple [the intake] up as much as possible, and do the same with the exhaust," says Banks. "The more you crumple this up, the shorter the length of the propulsion system, and the more flexibility the airframer has to design the aircraft."
POWER HUNGRY
Another focus area is an embedded starter-generator that could save space and provide the large amount of electrical power required by future fighters. Banks says power demand on fighters will rise exponentially, with electricity needed for powerful radars, electrically-actuated control surfaces and directed energy weapons.
Existing aircraft engines generate power through a gearbox underneath the engine, which drives a generator. In addition to adding moving parts and complexity, the space required outside the engine for the gearbox and generator makes the airframe larger, which is undesirable in a stealthy platform.
"By the time you've embedded all of this underneath, it increases the diameter of the installation," says Banks.
So R-R is working on fusing magnets to the rotating shaft of the engine, which can reach 15,000 rotations per minute. The placement of wires outside this creates an electric motor. "If you have magnetics rotating, and you have wires, you generate electricity."
In addition to generating power for the aircraft, the system can also serve as a starter generator. By energising the shaft with, say, power from a battery or a ground power unit, the engine winds up. Magnets can be applied to both the high and low pressure shafts, effectively creating two separate power generators.
"I can take more energy from one shaft, rather than the other," says Banks. "If have a surge issue at high altitude because the air is rarefied, I can unload the fan and direct energy from one shaft to the other, providing more surge margin. You can intelligently siphon off energy."
GOODBYE GEARBOX
"We can remove all of the gearbox underneath the gas turbine. Now we tell the airframer that all we need is a battery or electrical power source, and that starts your engine for you… it's a win-win. Everything is beneficial."
The company is also continuing to develop advanced composites that can reduce weight inside the engine.
Work is underway on these systems at Rolls-Royce's lab in Bristol. Banks stresses that the technologies are not being developed with a specific aircraft in mind, but for futuristic programmes in general. One of these, of course, is the prospective British-French Future Combat Air System (FCAS).
"If we can offer a slimline, power dense, propulsion system because we've (zabranjeno)ed distortion tolerance, and with electrical energy that's generated at the heart of the gas turbine – and not generated via generators mounted on the pad like at the moment – then everyone wins and you have a much more efficient system," he says.
https://www.flightglobal.com/news/articles/intervi.....ht-445940/
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