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[[GE Reports: Narendra Joshi on volcanic ash and jet engines]]
[[Sean Gannon-Managing Editor, GE] Hi, this is Sean Gannon, managing editor at GE, ]
[and I'm here right now on the phone with Narenda Joshi. ]
[He's in our Global Research Center.]
[He's in advanced technology propulsion.]
[So with all the groundings right now across Europe because of the volcanic eruption,]
[what exactly does it do to a jet engine when you fly through volcanic ash?]
[[Joshi] It depends upon the loading of the ash in the air.]
[If you have heavy content of ash in the air, ]
[then that ash will quench the combustion process]
[that is happening inside the jet engine, and it will flame out]
[the engine, and you lose power.]
[So, that is one thing that can happen because of ash content in the air.]
[The second thing ash can do is clog up the very fine cooling holes]
[that are used in the turbo machinery to keep the components cooled]
[in a very, very aggressive, hot environment. ]
[So if you plug up those holes, then there's a second level of problems and issues]
[that can be cause in turbo machinery that may not be realized instantly, ]
[but they will affect the performance of the turbo machinery.]
[So, we're very, very careful about that as well.]
[[Gannon] So when flying through--so, the ash goes into the engine, ]
[and the first part of it is actually just clogging it up]
[just because there's so much particle in the air. ]
[Is that the first step of the danger?]
[Yes. There are multiple things that happen with ash]
[because ash is composed of extremely fine but very hard particles.]
[So, you have compressor blades and fan blades which are turning at very high speeds]
[So, that's the first large problem that we run into.]
[Second thing is in the combustion process, downstream of the fan and the compressor,]
[where you have very high temperatures, you can actually melt the ash,]
[and this molten ash will go downstream into the turbo machinery]
[and coat the turbo machinery with a layer of ash.]
[So now, the turbo machinery is no longer as aerodynamic as it was supposed to be,]
[and you're disabling performance right there.]
[The second thing that ash can do is if there is a high loading of ash,]
[It can quench the combustion process]
[where you are releasing heat from the fuel. ]
[If that happens, the engine flames out and you lose all power instantaneously.]
[Even if you didn't lose all power instantaneously, going through ash cloud]
[will affect the performance of the engine downstream.]
[You may not think that you're affected in it right away.]
[You will affect engine performance.]
[[Gannon] Now, does it matter what type of jet engine it is?]
[Are there certain technologies that could one day address it?]
[I know we have a number of nano coatings we're working on.]
[Does anything matter or is it just simply ash isn't going to work with a jet engine]
[no matter what technology you have?]
[I think ash is not going to work with jet engines no matter what technology]
[because ashes are very, very hard--it is like quartz sand ]
[which is very, very high on the hardness scale--and so, the best thing is ]
[if you see an ash cloud stay clear of it.]
[Well--just for your record, Sean--the hottest part of the turbo machinery]
[downstream of the combustor where you burn the fuel]
[is a very, very aggressive, very high-pressure, very hot environment,]
[and the parts which are rotating in that hot environment are cooled by air]
[by laying down a thin film of air.]
[This is now getting down into the details of this.]
[There are small holes which create this film of air.]
[If those holes were clogged up, then the hot gases which are expanding around this blade]
