Jet Engines...

[Jumbo789]

So I'm in my Energy Systems class the other day, and we are doing a jet engine lab. The prof tells a story about at BA flight from Asia to Australia in the 80's. Apparently, it was flying along and the cabin started to get smoky. The passengers (and flight crew) noticed the wings starting to get red and the engines began belching balls of fire. This was all happening around 30000 ft altitude. After a while, the engines quit and the plane coasted down to 10,000 ft (the 747 can fly a long time with no engines...~20-25 minutes!) and the engines came back on. The pilot went back up to 30,000 feet and it did it again. They ended up landing on an island, and a mechanic came down to look over everything. He told the pilot that there was a volcanic ash "cloud" at around 30,000 ft, and the smoke was coming in through the ventilation system, the wings were getting hot from the "collision" of the particles and the wings, and the jet engines were using the ash as fuel and combusting it. Crazy, huh! This is why there are monitoring stations to look for these types of conditions because the passengers were probably a little scared...

[nthfinity]

yes, along with tons of ash, the surrounding air is suffocated of oxygen, and permiated with sulfer.... two things which are terrible with feul air ratios... i must say im not quite so sure about the wings glowing without the nosecone rising in temperature extremely as well.... 600ish mph' which is what the 747 usually does @ 30,000+ft. is a lot of friction with small solid objects for cirtain tho.

the engines belching balls of fire would be consistant with hitting enough oxygen to burn for a short time, but would be hell on the engine.

oh yeah, welcome to JW jumbo!

[Jumbo789]

Yeah, it sure would be a lot of friction. Nice to see someone with some technical know-how in a forum. Too many people who just know what others tell them in other forums I've been on. And thanks for the welcoming!

[coombsie66]

Yeah, about the wings, the viscous boundry layer effects are the main cause of the heating of the wing, and nose cone surfaces, unless the particles of ash had quite a inertia behind them, i doubt they would even be able to touch the wings, just following the flow above and below, although a minute proportion might collide at the stagnation point.
Interesting info about the ash playing havoc with the air fuel ratios! Never thought about that! Is that pretty standard teaching in aero nthfinity?

[Kangaroo Boy]

What are you studying Jumbo789 at Uni?

[nthfinity]

its pretty standard in 'mechanics andthermodynamics of propulsion':part 2 air breathing engines
combined with some chem I, and II knowlege base

also, i neglected to mention density issues with flying through the volcanic ash cloud. that would explain the shaking, in addition to the engines sputtering. a less dense clould would cause the plane to drop, while the altimiter shows a rate of asent, while the sulfer clould would cause just the opposite(i think its more dense then air?)

yes, under flawed early 'perfect fluid theory' models it would be much more possible to superheat the wings at such low velocities. with the leading edge pressure being quite high, it would be highly unlikely that any ash would even touch the wing, save unless it was a rather large piece, and the plane flew directly into an eruption
at high air velocities the viscous boundry layer is so thin, the pressures falls, and velocity rises: in effect routing almost all particles around the body. you have that quite right

[Jumbo789]

I'm studying Mechanical Engineering at Kettering University (used to be the General Motors Institute). Thankfully I'm done in about 4 weeks! It's been a good education--I even got to work on the Ford GT for about 3 months and see it in way pre-production (as in January 2003). It will be nice to get done, though!

[nthfinity]

I'm studying Mechanical Engineering at Kettering University (used to be the General Motors Institute). Thankfully I'm done in about 4 weeks! It's been a good education--I even got to work on the Ford GT for about 3 months and see it in way pre-production (as in January 2003). It will be nice to get done, though!

really? i used to live in grand blanc, and goto high school there! i also know a few people at, or who used to goto kettering! im currently @ WMU
congradulations on graduation! im still quite far off that one.

the ford gt is an amazing vehicle... im looking forward to possibly riding in one this june (small chance of driving it )

any idea where you want to work?... most engineering majors ship right off after graduation around here