High Bypass Turbofan Blade Tip Speeds (Not RPM)

[kontiki99]

Hi all, Anybody really know if some portion of a high bypass engine fan blade exceeds the speed of sound during normal operation?

It's really just a curiosity question.

Thanks,

 

[rb1957]

won't think so ... it'd be very inefficient

 

[KENAT]

I believe they tend to avoid it, though if memory serves those on the Pegasus as used in the Harrier might, can't recall for sure.

You might want to read up on propfans/UHB engines, and maybe even on geared fans.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[RPstress]

Commercial turbofan fan tips go about mach 1.5 at present (about M1.4 on the GE90, dia = 135", speed = 2550 rpm, tip speed = nearly 460 m/s or 1000+ mph). The next generation of engines will very likely have significantly higher specific fuel consumption and significantly lower fan speeds and bigger fans.

http://www.airliners.net/aviation-forums/tech_ops/read.main/156501/