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Volcanic Ash And Newer GE, Trent's And Pratts  
User currently offlinejustloveplanes From United States of America, joined Jul 2004, 1045 posts, RR: 1
Posted (4 years 4 months 6 days 21 hours ago) and read 6422 times:

Has any of the newer engine designs incorporated resistance to volcanic ash ingestion in any way? Appropriate topic these days........ Wondering if the larger engines like the GE-90's are more resistant

29 replies: All unread, showing first 25:
 
User currently offlineLMP737 From , joined Dec 1969, posts, RR:
Reply 1, posted (4 years 4 months 6 days 18 hours ago) and read 6323 times:

Nope, any ash sucked into a Trent, GE-90 or PW 4000 will make a mess just like it would on an older engine.

User currently offlinelitz From United States of America, joined Dec 2003, 1761 posts, RR: 0
Reply 2, posted (4 years 4 months 6 days 16 hours ago) and read 6153 times:
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Had I to guess (and since I'm by no means a propulsion engineer, this IS a guess) ... I'd say the newer engines are manufactured with tighter tolerances, to allow then to achieve the efficiencies they do ... and with that in mind, congealed ash inside the "hot" parts of the engine are going to be more damaging to a newer engine.

That stuff melts and coats everything w/a layer of silica (glass) ...

Remember Cash 4 Clunkers and what that stuff did to the car engines the gov't mandated be destroyed?

Picture that inside a jet engine ...

- _litz


User currently offlineprebennorholm From Denmark, joined Mar 2000, 6417 posts, RR: 54
Reply 3, posted (4 years 4 months 6 days 10 hours ago) and read 5894 times:

There is no way to make any turbine engine resistant to volcanic ash.

The main problem is that the ash melts in the combustion chambres, but when it hit the turbines, then it has been mixed with cold air so it "freezes" as glass on the turbine blades.

In addition it works as sandblasting the fan and compressor blades, and the whole exterior of the plane, including the front office windows.

So even if the ash cloud may be so thin that it causes no immediate "danger" for flight, then it is so damaging to the planes that flight becomes economically crazy.

Yesterday I saw the only viably solution to the problem in an email from Germany: Iceland equips all their volcanoes with filters.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlinejustloveplanes From United States of America, joined Jul 2004, 1045 posts, RR: 1
Reply 4, posted (4 years 4 months 6 days 9 hours ago) and read 5883 times:

I guess the question is not immunity, but damage tolerance and still keep flying. For example, one failure mode was the fuel nozzles clogging. The two 747's that survived did have all four engines shut down, and in both cases, all 4 were eventually restarted to land safely.

User currently offlinepilotpip From United States of America, joined Sep 2003, 3150 posts, RR: 11
Reply 5, posted (4 years 4 months 6 days 5 hours ago) and read 5742 times:

Even if you did make "ash proof" engines you'd still have a windscreen and leading surfaces that end up being trashed so bad the aircraft wouldn't be safe.

Quoting prebennorholm (Reply 3):
Yesterday I saw the only viably solution to the problem in an email from Germany: Iceland equips all their volcanoes with filters.

Funny!  



DMI
User currently offlineboeingfixer From Canada, joined Jul 2005, 530 posts, RR: 0
Reply 6, posted (4 years 4 months 6 days 4 hours ago) and read 5727 times:

Quoting justloveplanes (Reply 4):
For example, one failure mode was the fuel nozzles clogging.

Where did you get this info from? Fuel nozzles don't clog from the volcanic ash. The problem is down stream from the nozzles where the combustion heat turns the ash into glass.

The main failure point in turbine engines from volcanic ash is the accretion of glass particles on the nozzle guide vanes and turbine blades. This results in greatly reduced turbine efficiency and corresponding increase of EGT.



Cheers, John YYC
User currently offlineSampson777 From Canada, joined Mar 2010, 28 posts, RR: 0
Reply 7, posted (4 years 4 months 6 days 4 hours ago) and read 5726 times:

Hello there, found a link that you may find interesting

Flight Operations Briefing Notes --> Operating Environment -->Volcanic Ash Awareness


http://www.airbus.com/fileadmin/medi...fetyLib_-FLT_OPS-OPS_ENV-SEQ06.pdf

Figure 3 on Page 4 details the effects of ash on aircraft engines.

Cheers



Making Mom proud since 1989
User currently offlinejustloveplanes From United States of America, joined Jul 2004, 1045 posts, RR: 1
Reply 8, posted (4 years 4 months 6 days 4 hours ago) and read 5714 times:

Quoting boeingfixer (Reply 6):
Where did you get this info from? Fuel nozzles don't clog from the volcanic ash. The problem is down stream from the nozzles where the combustion heat turns the ash into glass.

Found it in one of the recent threads on web. I"ll look for a link...


User currently online9VSIO From United Kingdom, joined Dec 2006, 713 posts, RR: 2
Reply 9, posted (4 years 4 months 6 days 3 hours ago) and read 5695 times:
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Would it affect piston engines?


Me: (Lining up on final) I shall now select an aiming point. || Instructor: Well, I hope it's the runway...
User currently offlineWoosie From United States of America, joined May 2006, 115 posts, RR: 2
Reply 10, posted (4 years 4 months 6 days 3 hours ago) and read 5680 times:

"Would it affect piston engines?" I would think so, as the particle size is small enough to be normal aspirated into the combustion chamber. Not sure though.

User currently offlinejustloveplanes From United States of America, joined Jul 2004, 1045 posts, RR: 1
Reply 11, posted (4 years 4 months 5 days 23 hours ago) and read 5607 times:

Quoting justloveplanes (Reply 8):
Quoting boeingfixer (Reply 6):
Where did you get this info from? Fuel nozzles don't clog from the volcanic ash. The problem is down stream from the nozzles where the combustion heat turns the ash into glass.

Found it in one of the recent threads on web. I"ll look for a link...
http://www.cbsnews.com/stories/2010/...4/15/ap/national/main6400175.shtml

This link as well as several others mention clogging fuel nozzles. Googling "volcanic ash turbine fuel nozzle" gives several. They may be repeating each other, text looks similar....


User currently offlineMarkC From United States of America, joined Apr 2006, 259 posts, RR: 0
Reply 12, posted (4 years 4 months 5 days 19 hours ago) and read 5509 times:

Clogging the feul nozzles puzzles me also. I am well aware of their design, and how they fit into the engine. Obviously, these are at a very low temp, and molten ash would solidify on them, but, I would think it would be on the exterior, not on the outflow of the nozzle itself. I also would not think that the high compressor would not be able to heat the ash to a high enough temperature so that deposits would form on the nozzles.

The Nozzle guide vanes, and the HPT blades, are more likely. I have seen fine sand damage, and its probably the same symptom. The newer the engine, the more air is bled to cool the turbine blades and vanes. This is where sand and ash create big problems leading to excessive temperatures.

I really wonder what the exact mechanism of engines failing when going though an ash could. Does anyone know. I have a hard time believing its clogged nozzles. Is it the computer shutting the engine down because of over temp. This meaning the cooling is not working. I would believe that. Not much other particualte matter is going to stop a jet engine from running.


User currently offlinejetlife2 From United States of America, joined Jul 2006, 221 posts, RR: 25
Reply 13, posted (4 years 4 months 5 days 12 hours ago) and read 5313 times:

The GE90 has design features that direct a high fraction of particulates away from the booster (spinner and splitter design), and away from the HPC (VBV design). Material is ejected into the fan stream. As a result of this design, the level of erosion (from sand etc.) experienced in the HPC is low compared to earlier generation engines.

This design would also be beneficial in reducing the fraction of ash particulates introduced into the core. Neverthless, it is not eliminated and some will still enter. From that point on the effects would be the same.


User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 14, posted (4 years 4 months 5 days 10 hours ago) and read 5255 times:

Quoting Woosie (Reply 10):
I would think so, as the particle size is small enough to be normal aspirated into the combustion chamber. Not sure though.

I would think not, or to a lesser extent at least. Even relatively high flow filters are pretty good at controlling super fine talcum-like dusts. But the filter would surely clog up quick in more dense ash.


User currently offlineNicoEDDF From Germany, joined Jan 2008, 1099 posts, RR: 1
Reply 15, posted (4 years 4 months 5 days 10 hours ago) and read 5253 times:

Quoting jetlife2 (Reply 13):
The GE90 has design features that direct a high fraction of particulates away from the booster (spinner and splitter design), and away from the HPC (VBV design). Material is ejected into the fan stream. As a result of this design, the level of erosion (from sand etc.) experienced in the HPC is low compared to earlier generation engines.

Actually, I cannot really see where spinner and splitter design differ significantly from other modern turbofans.
Any details you might share?

Also I fail to see, where the design of the VBVs can help in eject material into the fan system?
They way I see it, hard particles in the air stream are distributed equally across the crosssection (of course not in the case of single stones or other larger hard bodies). So in effect, bleeding off part of the core stream into the fan stream will reduce hard particles proportionally.
I can't see where this is any different to CF6-80s VBV design.

Where am I wrong?

rgrds,
Nicolas


User currently onlineMD-90 From United States of America, joined Jan 2000, 8505 posts, RR: 12
Reply 16, posted (4 years 4 months 5 days 10 hours ago) and read 5219 times:

Quoting Woosie (Reply 10):
"Would it affect piston engines?" I would think so, as the particle size is small enough to be normal aspirated into the combustion chamber. Not sure though.

I think the proper question is how long would the air filter last before becoming clogged? Ash shouldn't be able to make it past the filter so getting it inside the engine shouldn't be an issue.


User currently offlineWoosie From United States of America, joined May 2006, 115 posts, RR: 2
Reply 17, posted (4 years 4 months 5 days 9 hours ago) and read 5196 times:

Quoting MD-90 (Reply 16):
I think the proper question is how long would the air filter last before becoming clogged? Ash shouldn't be able to make it past the filter so getting it inside the engine shouldn't be an issue.

Not knowing a ton about piston engines, I was unaware that they use air filters. Makes sense but don't recall air filter cannisters, etc... I've only worked on a Mallard seaplane, which uses large radial piston engines. Thanks for the correction.


User currently offlinejetlife2 From United States of America, joined Jul 2006, 221 posts, RR: 25
Reply 18, posted (4 years 4 months 5 days 9 hours ago) and read 5195 times:

Quoting NicoEDDF (Reply 15):
Actually, I cannot really see where spinner and splitter design differ significantly from other modern turbofans.
Any details you might share?

Also I fail to see, where the design of the VBVs can help in eject material into the fan system?
They way I see it, hard particles in the air stream are distributed equally across the crosssection (of course not in the case of single stones or other larger hard bodies). So in effect, bleeding off part of the core stream into the fan stream will reduce hard particles proportionally.
I can't see where this is any different to CF6-80s VBV design.

The architecture is the same but the trajectories taken by particles are very different. Compare the two cross sections and imagine a particle... trace the angles from the front of the spinner, and between the booster and HPC, and you will see the differences in both areas. Also, particles are not evenly distributed across the cross section once they have entered the engine. The air flow imparts a radial outward velocity and particles thus favor the outer diameter. So by preferentially orientating the VBV door entrances and curve of the passage, heavier particles are removed in a way that does not occur on other engines.


User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 19, posted (4 years 4 months 5 days 8 hours ago) and read 5171 times:

Quoting Woosie (Reply 17):
I've only worked on a Mallard seaplane, which uses large radial piston engines. Thanks for the correction.

I may be wrong but I don't think I've ever seen a larger piston engine plane (radials or anything more than 6cyl) with a filter system. I'm assuming it's due to the much higher airflows required for those big engines.

Almost all light GA, twins, and high performance GA planes with 4 or 6 cylinder boxer engines have them however.


User currently offlinejustloveplanes From United States of America, joined Jul 2004, 1045 posts, RR: 1
Reply 20, posted (4 years 4 months 4 days 23 hours ago) and read 5049 times:

Quoting jetlife2 (Reply 18):
The architecture is the same but the trajectories taken by particles are very different. Compare the two cross sections and imagine a particle... trace the angles from the front of the spinner, and between the booster and HPC, and you will see the differences in both areas. Also, particles are not evenly distributed across the cross section once they have entered the engine. The air flow imparts a radial outward velocity and particles thus favor the outer diameter. So by preferentially orientating the VBV door entrances and curve of the passage, heavier particles are removed in a way that does not occur on other engines.

Tim Clark of EK said one of the things that was good about their 77W's was the lack of any performance degradation after 8 months, which he termed exceptional. Perhaps some of this due to the cleaner air flow to the core.


User currently offlinejetlife2 From United States of America, joined Jul 2006, 221 posts, RR: 25
Reply 21, posted (4 years 4 months 4 days 19 hours ago) and read 4941 times:

Quoting justloveplanes (Reply 20):
Tim Clark of EK said one of the things that was good about their 77W's was the lack of any performance degradation after 8 months, which he termed exceptional. Perhaps some of this due to the cleaner air flow to the core.

Yes that's right. Amongst other things designed to keep the engine the way it left the factory, as long as possible. Core degradation, including among other things compressor erosion, is a big player in fuel burn deterioration.


User currently offlineDocLightning From United States of America, joined Nov 2005, 19495 posts, RR: 58
Reply 22, posted (4 years 4 months 3 days 1 hour ago) and read 4375 times:

Wait, if an engine has to pass a sand ingestion test, why is volcanic ash different?

User currently offlinejustloveplanes From United States of America, joined Jul 2004, 1045 posts, RR: 1
Reply 23, posted (4 years 4 months 3 days ago) and read 4352 times:

Quoting DocLightning (Reply 22):
Wait, if an engine has to pass a sand ingestion test, why is volcanic ash different?

Volcanic ash melts and forms glass (raw material = Silicon) and coats parts at high turbine temperatures. Obsidian FYI is sometimes termed volcanic glass.

Sand I am guessing stays more intact. Sand is mostly SiO2 (silicon dioxide), which is already reacted Silicon in a stable form, whereas volcanic ash is (apparently) a more volatile/reactive form.


User currently offlineDocLightning From United States of America, joined Nov 2005, 19495 posts, RR: 58
Reply 24, posted (4 years 4 months 2 days 13 hours ago) and read 4102 times:

Quoting justloveplanes (Reply 23):
Sand I am guessing stays more intact. Sand is mostly SiO2 (silicon dioxide), which is already reacted Silicon in a stable form, whereas volcanic ash is (apparently) a more volatile/reactive form.

that makes sense. Does sand have a higher melting temperature?


25 KELPkid : Yes, mostly by clogging the air filter...and if you turned on carb heat or opened the alternate air intake, you would ruin the engine (just like dump
26 jetlife2 : There is no sand ingestion test.
27 Post contains links AKiss20 : El GE90 tiene caracter Standard SiO2 sand has a melting temp of about 1300-1500 degrees C. Volcanic ash is more around 1100 May not be required but ht
28 Post contains links 777wt : http://www.youtube.com/watch?v=IMIkk...aynext_from=PL&playnext=1&index=45
29 MarkC : Sand does the same thing. High altitude fine sand. I have seen the internals of a middle east PW4000 operator. They show the long term effects of fine
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