setting fire to cis - or- small scale combustion chamber and instrumentation

SettingSetting FireFire to CISto CIS- or- - or-

Small Scale Combustion Chamber Small Scale Combustion Chamber and Instrumentationand Instrumentation

Dave PogorzalaDave Pogorzala

Bob Kremens, PhD, AdvisorBob Kremens, PhD, Advisor

Center For Imaging ScienceCenter For Imaging Science

Rochester Institute of TechnologyRochester Institute of Technology

05.10.0205.10.02

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Digital Imaging and Remote Sensing LaboratoryDigital Imaging and Remote Sensing LaboratoryDigital Imaging and Remote Sensing LaboratoryDigital Imaging and Remote Sensing Laboratory

• history

• project goals

• research methods

• results

• conclusions / future work

overview:

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• the Forest Fire Imaging Experimental System (FIRES) team traveled to the Fire Sciences Lab (FSL) in Missoula, Montana during the summer of ’01.

• there they used a large combustion chamber to image several

fires with the ASD, an IR Radiation Pyrometer, and a

visible / IR camera

history:

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• we want to be able to image fire at any time

• construct a small-scale, self standing combustion chamber- what features from the FSL facility are needed?

• allow the chamber to be tailored to other specific uses- Adam and Jim’s project- work to be done this summer

• test the chamber- does it hold up to a full-fledged fire?- will the instruments be able to image the fire?

project goals:

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combustion chamber facility at the FSL

Burn surfaceBurn surface

Smoke hoodSmoke hood

InstrumentsInstruments

BryceBryce

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project goals:

• find fire’s emissivity- emissivity- the ratio of the radiance emitted by an object at a certain temperature to the radiance by a perfect blackbody at that same temperature

- “We definitely need, at a minimum, the emissivity and temperature profiles of the flames to model a fire with DIRSIG”

- Bob Kremens

- come to a conclusive value that could be published

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research methods: chamber design

• initial design was simplified

- research was done on flume dynamics- no need for smoke hood and fan

- burn surface can be simulated with an outdoor grill

- camera ports were made square- easier to modify their size

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research methods: data acquisition

• both instruments had to be interfaced with the computer

-developed thermocouple data logging program in VB

-used preexisting program with the pyrometer

thermocouple pyrometer

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experimental setup

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combustion chamber facility at CIS

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Flux (W/cm2) = * * T4

pyrometer thermocouples

calculatedemissivity

research methods: calculating the emissivity

unfortunately, it was not this easy

• the Steffan-Boltzmann Law

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• both instruments yielded temperature data- thermocouples measured actual temperature of the flame- pyrometer interpreted detected radiance as temperature assuming an emissivity of 1.0

• emissivity was found using a look up table


but it still wasn’t this easy

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• the pyrometer’s rise time coefficient is < 1 sec

• the thermocouple’s rise time is ~ 45sec

• in order to correlate the two sets of data, a Fourier analysis had to be done on the pyrometer data

- frequencies above 1/45 cyc/sec were removed

• resulting pyrometer data was more “stable”


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temperature vs. time

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• temperature was read from the new pyrometer data ( )

• this was used to find the fire’s radiance; =1.0 ( )

• this radiance was found at the fire’s actual temp ( )

• the union of the pyrometer’s radiance and the thermocouple’s temperature yielded the emissivity ( )


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• a set of 12 individual samples in time gave an average emissivity of 0.265

• H. P. Telisin (1973)* measured emissivity under various weather and fuel conditions, resulting in a range of 0.1 – 0.58

results:

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• this figure of 0.265 can be trusted, but will be verified by additional testing this summer

• add up to 5 more thermocouples to simultaneously monitor the fire in various locations

- do temperature variations give different emissivities?

• collect data on different species of wood- different chemical compositions could yield their own emissivities

• automate the LUT process in IDL

conclusions / future work:

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• Bob Kremens, PhD

• Don Latham - Project Leader, Fire Sciences Lab, Missoula, MT

• Al Simone

* Telisin, H. P. 1973, “Flame radiation as a mechanism of fire spread in forests”, In: Heat Transfer in Flames, Vol. 2. (N.H. Afgan and J.M. Beer, eds.), 441-449. John Wiley, New York

acknowledgments:

setting fire to cis - or- small scale combustion chamber and instrumentation

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