Shu Fung, from GE and an EAA chapter 1114 member organized today a special visit of the GE plant located in RTP on Miami Boulevard. There were about 25 members, all very interested and a few quite competent about jet engines. The best part of the visit is that Shu who is working at the plant is passionate about the jet engine business and managed to communicate his passion to an already very motivated group. The result: a visit planned for 1 hour and a half lasted close to 4 hours! We even saw the engine Alliance GP7000 that equips the A380, that is, the one that does not blow-up in flight...
A few things we learned about modern jet engines:
- The blades of the first stage compressor move to change their angle of attack in order to fight stall, not unlike the wing of an aircraft. This is of course computer controlled as a stall of the compressor would result in a flame out and a few other bad things for the engine longevity.
- The blades and enclosures of the turbines behind the combustion chamber are cooled by air ducked from the compressor chambers.
- The engine starter is not mechanically linked to the turbine shaft, it is just a compressor that pushes air into the combustion chamber to get the blades moving until the ignition and combustion of fuel takes over
Now next time we fly an airliner, we will know what's behind these big cowlings. Whether this will make us more comfortable flying is another story... Did you say A380?
I like my Rotax 912S.
Nice, JP. Small correction - the spinning rotor blades' angle does not change, it is the angle of the stators that are attached to the outer casing that change their angle under certain conditions. The stators are there to tweak the incoming airflow to the ideal angle of attack that the spinning rotor sees. Not doing this correctly can lead to stall, just like on a wing whose angle of attack become excessive. In a jet engine, this is called compressor stall, and it's pretty rare these days thanks to these advanced designs and smart people like Shu. I also enjoyed seeing the GENX which has some truly amazing technology hidden within its systems, and reduces specific fuel consumption by 15% compared to the CF6 it replaces on the B787 it will power. 1-2% would be impressive, but 15% is astounding. Details on the GENX can be found here:
ReplyDeletehttp://www.geae.com/engines/commercial/genx/index.html
A disclaimer - all the jet engine makers have been my clients for many years. It has been a real treat to see these new engines go from the drawing boards to flight the past 10 years. Especially evident was the highly 3-dimensional nature of all the blades we saw. Only a few years ago, this was a dream for future engines, now it's reality. But also what one would expect from the folks at GE, "Generous and Easy" as we used to call them (my father and grandfather were both GE engineers)
Kent Misegades