tupolev154b2
Posts: 1269
Joined: Mon Jun 26, 2000 9:01 am

Glowing Rings Of Afterburners

Mon Aug 20, 2001 9:19 am

Why do afterburners produce some sort of glowing rings in the cone extending from the exhaust pipe when they are on?
 
Twotterwrench
Posts: 1087
Joined: Tue Jan 16, 2001 5:57 pm

RE: Glowing Rings Of Afterburners

Mon Aug 20, 2001 1:45 pm

They are shock waves created by the supersonic airflow exiting the afterburner.
 
aeroguy
Posts: 66
Joined: Wed Aug 15, 2001 1:33 am

RE: Glowing Rings Of Afterburners

Tue Aug 21, 2001 1:19 am

Yes, those rings you are seeing are caused by a series of expansion waves and oblique shock waves within the exhaust jet. They are constantly reflected off the boundary surface (which is the interface between the high speed jet and the surrounding air). An oblique shock reflects off the boundary surface and becomes an expansion wave and an expansion wave reflects off the boundary surface and becomes an oblique shock. These reflections, shock diamonds I guess you could call them, deflect the air flow in the jet and actually cause changes in diameter of the boundary surface. You can actually see this if you look closely and observe that the jet doesn't have a constant diameter, but rather bulges in and out. A really interesting phenomenon, I haven't found any pictures of it on Airliners.net, maybe some other people have...
 
tupolev154b2
Posts: 1269
Joined: Mon Jun 26, 2000 9:01 am

RE: Glowing Rings Of Afterburners

Tue Aug 21, 2001 4:00 am


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