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texl1649
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CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 11:26 am

https://twitter.com/flightglobal/status ... 39014?s=21

Image

Curious if this has been discussed.

AWST Link; https://aviationweek.com/aerospace/cfm- ... gen-engine

CFM International joint venture partners GE Aviation and Safran have launched an aggressive technology development program to pave the way for a new generation of fuel-efficient unducted—or open fan—engines to enter service around the mid-2030s.

Also known as an open rotor engine, the open fan concept increases bypass ratio by eliminating the fan duct and offers double-digit efficiency gains due to a lower fan pressure ratio. The new engine will be developed as part of a suite of disruptive technologies under CFM’s newly unveiled Revolutionary Innovation for Sustainable Engines (RISE) program.

Targeting a 20% reduction in fuel consumption and CO2 emissions compared to current engines, RISE is aimed at the next generation of single-aisle airliners. The open fan program forms the foundation for a potential successor to CFM’s conventional direct-drive Leap-1 turbofan and offers the most realistic development opportunity yet for unducted fan technology since tests of the concept began in the 1980s.


From a regulatory perspective, this would be a challenge to certify I’d think as loss of a rotor would necessarily risk hitting the other engine (or passengers if on a wing).
 
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armagnac2010
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Re: CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 12:50 pm

From a regulatory perspective, this would be a challenge to certify I’d think as loss of a rotor would necessarily risk hitting the other engine (or passengers if on a wing).


EASA worked with industry to propose regulatory material allowing installation of open rotor engine; the proposal was never finalised, simply because no project was actually coming on the market. The EASA effort pre-dates the launch NEO/MAX projects. It can probably be revived.

https://www.easa.europa.eu/sites/default/files/dfu/NPA%202015-22.pdf

Early open rotor designs would have been indeed very challenging to install on any airframe; they featured 2 close coupled counter-rotating rotors, and failure of a single blade would have resulted in disintergration of both rotor stage, with a hull loss the likely outcome. Later concepts had more space between rotors, solving the issue, as well as being less noisy; the engine was larger thus heavier. Fuselage impact can be addressed by advance in technology, composite material for blades and the fuselage itself allow for frangible blades and shielding of structure.


The Rise concept is slighlty different, with only one rotating stage and fixe guide vanes.
 
docmtl
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Joined: Sun Feb 25, 2018 12:04 pm

Re: CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 1:02 pm

An turboprops have rotating blades uncontained by design...
 
WayexTDI
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Re: CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 1:05 pm

texl1649 wrote:
https://twitter.com/flightglobal/status/1406899917872939014?s=21

Image

Curious if this has been discussed.

AWST Link; https://aviationweek.com/aerospace/cfm- ... gen-engine

CFM International joint venture partners GE Aviation and Safran have launched an aggressive technology development program to pave the way for a new generation of fuel-efficient unducted—or open fan—engines to enter service around the mid-2030s.

Also known as an open rotor engine, the open fan concept increases bypass ratio by eliminating the fan duct and offers double-digit efficiency gains due to a lower fan pressure ratio. The new engine will be developed as part of a suite of disruptive technologies under CFM’s newly unveiled Revolutionary Innovation for Sustainable Engines (RISE) program.

Targeting a 20% reduction in fuel consumption and CO2 emissions compared to current engines, RISE is aimed at the next generation of single-aisle airliners. The open fan program forms the foundation for a potential successor to CFM’s conventional direct-drive Leap-1 turbofan and offers the most realistic development opportunity yet for unducted fan technology since tests of the concept began in the 1980s.


From a regulatory perspective, this would be a challenge to certify I’d think as loss of a rotor would necessarily risk hitting the other engine (or passengers if on a wing).

How would it be challenging? The FAA and EASA already certify turbo-prop planes; this is the same principle.
 
amstone17
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Re: CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 1:16 pm

This is the re-birth of the UDF engines from the 80s. GE's contribution being the most developed UDF program ever made, with a lot of flight testing data to build a brand new version of the same concept with modern materials and knowledge.

The risks of such engines aren't far removed from failure risks on turboprops, the rotation speeds aren't quite the same as a fully contained turbofan/jet.

What killed the original UDF concepts was mainly noise, that's where the challenge is. The thing about modern turbofans is a ton of noise reduction efforts go into the cowling design. Take the cowling away and you have to deal with all that noise again. Will be interesting to see what CFM does about it in this age of ever quieter aircraft.
 
cpd
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Re: CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 1:25 pm

amstone17 wrote:
This is the re-birth of the UDF engines from the 80s. GE's contribution being the most developed UDF program ever made, with a lot of flight testing data to build a brand new version of the same concept with modern materials and knowledge.

The risks of such engines aren't far removed from failure risks on turboprops, the rotation speeds aren't quite the same as a fully contained turbofan/jet.

What killed the original UDF concepts was mainly noise, that's where the challenge is. The thing about modern turbofans is a ton of noise reduction efforts go into the cowling design. Take the cowling away and you have to deal with all that noise again. Will be interesting to see what CFM does about it in this age of ever quieter aircraft.


Could legislation on noise be a potential risk to these engines? If a future SST wouldn’t be acceptable on engine noise being louder than normal modern jet aircraft then this surely won’t pass that test either if it is also louder.
 
744SPX
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Re: CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 2:42 pm

Extensive thread on this in Tech/Ops
 
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janders
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Re: CFM Open Rotor concept demonstrator (UDF)

Mon Jun 21, 2021 2:54 pm

See ingoing discussion

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