Subject: | Re: leaking planes Re: [really OT] (was: Re: [OM] OM] OT - Titanium) |
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From: | "gary edwards" <maitani@xxxxxxxxxxx> |
Date: | Tue, 10 Aug 1999 12:09:15 PDT |
Any supersonic jet will have a pattern of oblique shock waves originating
generally at the nozzle exit plane (the term "jet" is used here to refer to
the stream of fluid discharged from the nozzle.) These shock waves reflect
("bounce") from the jet boundary back into the jet in the characteristic
diamond pattern. The angle formed by the diamonds is related to the flow
Mach number - faster=longer diamonds. These shock waves are visible in some
cases due to the different index of refraction across the shock wave. Jet
engines that do not produce a supersonic exhaust jet do not display shock
diamonds. Most engines produce supersonic jets only when operating in
afterburner ("reheat") and the articulated nozzle petals are closed down to
form a convergent-divergent nozzle. All rocket engines have shock diamonds
but in many cases (like the classic slow-motion Saturn V launch sequence),
the diamonds are not visible due to the incandescence of the exhaust gases.
The incandescence doesn't allow you to see through the jet.
OM Content: When photographing jet aircraft in afterburner you may have a better chance of capturing the shock diamonds if the exhaust jet is somewhat backlit. That is how we photographed control rocket simulators that used cold nitrogen as a working fluid. Gary Edwards From: Chris Barker <cmib@xxxxxxxxxxx> Reply-To: olympus@xxxxxxxxxxxxxxx To: olympus@xxxxxxxxxxxxxxxSubject: Re: leaking planes Re: [really OT] (was: Re: [OM] OM] OT - Titanium)Date: Tue, 10 Aug 1999 13:53:45 +0200 >on my page shortly thereafter. What causes the diamonds in the exhuast >plume? > >/Acer Victoria All "decent" engines have them (the Tornado's RB199 does not) - nb personal prejudice, not scientific observation. I believe that it is the formation of Mach cones in the exhaust that shapes the flame into 'V' or diamond shapes. Chris _______________________________________ Chris Barker <>< mailto:cmib@xxxxxxxxxxx Box 2, Officers' Mess, RAF Brueggen, BFPO25, UK. < This message was delivered via the Olympus Mailing List > < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx > < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html > _______________________________________________________________ Get Free Email and Do More On The Web. Visit http://www.msn.com < This message was delivered via the Olympus Mailing List > < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx > < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html > |
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