Good stuff. Are there any details available on the wear-resistant coatings from Timken? I'm curious if they're using a fluropolymer base or if they are achieving superior tribological properites through some other technology.
There isn't a typo but the quote: “One reason the PurePower engine is a first is because there are no tapered roller bearings in main shaft positions,” might be slightly more clear if it had read “there are currently no tapered roller bearings in main shaft positions”. You're right this is a major innovation becausethe PurePower engine is the first to use this type of bearing for a jet engine design. Thanks.
Ivan, the Pratt & Whitney PurePower® geared turbo fan (or GTF) uses a speed reduction gearbox between the engine’s low-pressure turbine and fan. The GTF allows the engine’s low-pressure turbine to operate at higher rotational speeds for peak efficiency, while the engine’s fan operates at lower speeds compatible with optimum propulsive efficiency and significantly lower levels of noise. In combination, the GTF provides enhanced fuel efficiency and reduced levels of noise in an engine that is also lighter, and lower in maintenance cost, than conventional turbo fan engines.
I suspect a misquote! The article's quote says there are no tapered roller bearings but then goes on to tout their advantages over a combination of ball and cylindrical bearings. Subsequent details show this to be a major improvement.
The geared fan feature is interesting but it is not clear exactly how this contributes to the efficiency improvements. Does the geared section step up the main fan rotation speeds or step them down? I would guess down so the power turbine section can rotate faster and drive a slower but larger main fan section for the bypass air.
In my power systems class in college my classmate and I wrote a computer program to analyze the Thrust Specific Fuel Consumption (tsfc) on a low bypass turbofan engine. I wish I had the code for that now. It would be interesting to note some of the technical characteristics of the engine compared to previous designs. The improvements sound dramatic and I would like to know more details about how they were achieved. A specially optimised combustor and tapered roller bearings are interesting but only whet my appetite for the details.
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