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keesje
Posts: 9768
Joined: Thu Apr 12, 2001 2:08 am

Boeing 7E7, Airbus 380, Fanmail & Shafts

Fri Sep 24, 2004 6:10 am

Contrary to what I read on this site IMO the advantages of the new generation of the new bigger turbo fans (GP7200, Genx, Trent1000) is not in the fact they do/don´t give bleed air, work only in combination with an advanced wing or whatever.

You can see the fanblades are more complex then the existing straight ones, like used in the GE90. http://www.klm-engineering-maintenance.com/media_relations/image_library/images/21_rel3_LM_777_H11.jpg
GE-90 blades are cabonfibre, but still have the conventional shape, the best compromise for the different fan speeds/functions. (the newer -115´s have new ones)


RR Trent1000

New engine fan blades´ are shaped by 3 functions (from hub to tip)
- providing sufficient pressure for the compressor close behind
- providing maximum efficiency in the middle (most of the ´thrust´)
- close to the tip it is bended to minimize supersonic interference with the cowling


GEN-X

These more "ideal" shapes of the fan blades are known for a long time but blades with these complex shapes could not withstand the enormous forces. Now they can be made of carbonfibre (GE) or hollow titanium (RR) they can.

Where the traditional fanblades had to be heavy close to the hub to absorb the forces, the new blade are more smaller at the root, enabling a smaller hub and thereby increasing the available airflow& bypass ratio within the same overall engine cross section.

Apart from this they have better fuel mixing, contra rotating shafts etc. But I believe the biggest gains come from the new fan, more specifically from the materials that make them possible.

so IMO : it´s mainly the fans ! anybody know if this is right?
"Never mistake motion for action." Ernest Hemingway
 
gigneil
Posts: 14133
Joined: Fri Nov 08, 2002 10:25 am

RE: Boeing 7E7, Airbus 380, Fanmail & Shafts

Fri Sep 24, 2004 6:48 am

The GE90-115B, the GP7200, and Trent 900 all feature swept blades with 3D aerodynamic technology throughout the engine. Its not new tech at this point.

The GENX and Trent 1000 will benefit from compressor enhancements as well as the already developed fan technologies.

N
 
DfwRevolution
Posts: 8828
Joined: Sat Jan 09, 2010 7:31 pm

RE: Boeing 7E7, Airbus 380, Fanmail & Shafts

Fri Sep 24, 2004 7:19 am

so IMO : it´s mainly the fans ! anybody know if this is right?

Even though the fan blade is crucial to the engine's efficency, they are only one of many contribuiting factors. A lean-desiel engine is very efficent, but a desiel-electric hybrid is even more so. This is the analogy I'm drawing between advanced fan blades and bleedless engine cores: one's great, but both are better.

Also, a fan blade improves the efficency of the engine only, whereas bleedless systems reduce weight and complexity of dozens of other systems across the aircraft.

Contrary to what I read on this site IMO the advantages of the new generation of the new bigger turbo fans (GP7200, Genx, Trent1000) is not in the fact they do/don´t give bleed air, work only in combination with an advanced wing or whatever.

Like I said above, advanced fan blades are an engine technology, bleedless cores are an airframe technology that just so happens to be inside the engine. Re-introduce bleed-air into the GeNEX and Trent 1000 and you basically have scaled down versions of existing engines.... bleedless engines are the new wave, advanced fan blades are the old wave that's just now coming of age.

[Edited 2004-09-24 00:23:43]
I have a three post per topic limit. You're welcome to have the last word.
 
User avatar
keesje
Posts: 9768
Joined: Thu Apr 12, 2001 2:08 am

RE: Boeing 7E7, Airbus 380, Fanmail & Shafts

Thu Sep 30, 2004 10:17 pm

The GE90-115B, the GP7200, and Trent 900 all feature swept blades with 3D aerodynamic technology throughout the engine. Its not new tech at this point.

.. advanced fan blades are the old wave that's just now coming of age


Advance fan blades as now introduced are certainly not the "old wave". It was imposible to make them until a few years ago & they have significant impact on overall efficiency. In the thrust rate class of the 7e7/330/747 there is just no engine available with this new technology.

With the GE90-115B being the only engine certified sofar I wonder what isn't "not new" & "old wave" in your opinion..


RR trent 900


"Never mistake motion for action." Ernest Hemingway

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