Message Board Thread - "IR application for jet engine flume"

Title	By	Posted On
IR application for jet engine flume	Bharat	1/8/2004
I have seen some IR images of jet engines and the story ends there. Does anybody have IR application examples for jet engine exhaust? Is the LW camera good enough for this application? Thanks.
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Jet engine exhaust temperatures	Marv	1/14/2004
the answer depends on what you are looking for. If you are looking for exact temperatures you will need a high temperature filter for what ever camera you use to record the image.
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Exhaust Thermography	Equine Bandit	1/14/2004
Flame exhaust is difficult due to the fact that gasses have very little emmisivity. You would be better off providind a black surface to capture the relative temperature off of it. Short Wave units may be a little better for this application.
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IR measurement of jet exhausts	Jim T.	1/14/2004
In my experience, the IR camera is a very useful tool for measuring jet exhausts. The key is to know what information you are looking for, and what information the camera can give you. If you are interested in looking at metal temperatures within the exhaust duct, you will need a longwave camera so that most of the exhaust is not visible. If you are interested in the exhaust itself, you will need a midwave (3-5 micron) camera. This is because the emission from an exhaust plume is due almost entirely to carbon dioxide and water vapour. This assumes of course that there is little or no soot. CO2 and H2O emit spectrally, with a strong band around 4 microns. The spectral nature of the emission will make it difficult to back out a temperature from your IR images. It is not possible to assign a simple emissivity to a plume emission. In the past, I've either used t/c probes within the exhaust stream, or a calibration curve (ie. measure the emission from a series of plumes of known temperature).
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Measured Emissivity	tjp	1/14/2004
I have from an old source (reference long lost) that the emissivity of exhaust gases (600 -700 C)of an engine in the 3 micron wavelength range to be unity
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IR measurement of jet exhausts	PIOTR	1/14/2004
My opinion is similar to Jim's T. Maybe it is worth to add only particular value of matching camera to the spectral features of the exhausts (aerosols + gases both of heterogenious density, pressure and temperature out of exhaust duct. Using source of uniform background Temp. outside the tested flow can help, additionally, to solve the problem.
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a props message from tjp ;"Measured Emissivity"	PIOTR	1/14/2004
In my opinion it was truly old reference. Unfortunately there are a lot of papers showing IR Thermography as obvious and correct response for almost all needs. It is so simple: push the button and read T scale...
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Thermograms of enginge exhaust	PIOTR	1/14/2004
I have a few old thermograms(1992)made using AGEMA 880 LW and 680 SW cameras with the aim to investigate temperature changes on the airport concrete caused by jet engine exhausts. You may find me on the web using http://www.pirs.pl/ Piotr Pregowski /PIRS, Pl/
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Lets look for problem from other side ...	Dr.Fil	1/15/2004
Collegues, can we recomend use for study of jet flame large size "black body" (e=0.8...09) and look for absorption of IR radiation by jet flume - we also can use IR filters for study some nonequlibrum temperature distribution. Good idea also use CO2 laser with optical expander and IR filter...
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exhausting work	Doug B	1/15/2004
I worked on this about 15 years ago and agree with some of what Jim T and Piotr said. There's really quite a lot to it and it's not simple or straightforward. And there's a big difference between jet and rocket plumes. I've collected a lot of information on technology for doing this, and wrote a report on what I did and what could be done. Contact me to discuss it if you're interested.
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