Forum: Technology

The title says it... why does an exhaust plume (at least in some cases) have a series of glowing and non-glowing points behind the nozzle, generally each glowing less intensely than the one before until there are no more, instead of a more constant decrease in glowingness starting at the nozzle?

http://www.aerospaceweb.org/aircraft/re ... r71_18.jpg

http://www.air-and-space.com/19811031%2 ... 11%20l.jpg

http://www.air-and-space.com/19971018%2 ... er%20l.jpg

http://image.dieselpowermag.com/f/edito ... burner.jpg

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http://www.aerospaceweb.org/question/pr ... 0224.shtml

I wonder if the afterburner exhausts has a sort of sinusoidal/harmonic wave-like nature to it and the "impulses" are more like the flame being sandwhiched by a series of harmonic nodes. That's my guess before reading all the links. We'll see if I've learned anything from all these engineering classes I've been taking.

Read the link in the answer. basically, the Mach shock waves criss cross each other and become constructive/destructive, much like sound waves in a poorly designed auditorium. One seat can have perfect acoustics and the ones right next to it are muddled and quiet.

Forum: Technology

Exhaust plumes: why in pulses?