Fire/Arson Investigations : Fire/Arson Investigations
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Re: If you were a Judge
Posted by: dcarpenter (IP Logged)
Date: June 02, 2007 09:05AM
Gerald,
Your explanation based on fundamentals produces a reasonable hypothesis. Again, mixing is the important quantity of interest in this case and is very much rate dependent. The question that needs addressing in order to test this hypohtesis is: is the rate of air flow created by this configuration sufficient to cause a backdraft?
The testing of this hypohtesis will require a determination of the flow rate and mixing in the attic (especially with respect to the local conditions around potential ignition sources) either experimentation or the use of a model that can handle the specific boundary conditions associated with an attic fire and the dynamics of vertical flow across a horizontal vent. A CFD model would be a reasonable tool to provide such a mixing study. These studies are routinely performed in the design of the combustors for gas turbines.
Doug
Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
www.csefire.com
Your explanation based on fundamentals produces a reasonable hypothesis. Again, mixing is the important quantity of interest in this case and is very much rate dependent. The question that needs addressing in order to test this hypohtesis is: is the rate of air flow created by this configuration sufficient to cause a backdraft?
The testing of this hypohtesis will require a determination of the flow rate and mixing in the attic (especially with respect to the local conditions around potential ignition sources) either experimentation or the use of a model that can handle the specific boundary conditions associated with an attic fire and the dynamics of vertical flow across a horizontal vent. A CFD model would be a reasonable tool to provide such a mixing study. These studies are routinely performed in the design of the combustors for gas turbines.
Doug
Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
www.csefire.com
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