Exploratory Studies Of Convective Flows Due To Arc Tracking

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Title: Exploratory Studies Of Convective Flows Due To Arc Tracking
Author: Mitchell, Richard R
Abstract: The objective of the research was to develop an understanding of how a flame propagates through an electronic enclosure . FLUENT® , a Navier -Stokes solver , was chosen due to its widespread commercial use , the availability of turbulence models and its ability to handle combustion . The relevance of this study with respect to the aerospace and domestic appliance industry was shown through case reports . Initial observations were made on arc discharges , chemical compounds and their relevance to establishing the flame . Experimental bench tests highlighted the instigating factors for flame ignition . The first round of bench testing revealed that solder node separation played an important role in establishing an arc discharge . Next , a water /Solventol solution was added to the tests to sustain the arcing of the solder nodes . Once the arc discharge was sustained , the next round of testing moved into the initiation of the flame on a printed circuit board (PCB ) . The bench testing showed that a minimum solder node separation of 1mm was necessary to achieve arcing with the water /Solventol solution at 120 VDC . The results also indicated that ignition of the flame was possible after several seconds of arcing occurred on the PCB panel . A method of flame suppression , through expanded metal foil , was suggested . The control volume was described in detail starting with the computer aided design drawing in Pro /ENGINEER . The preprocessing software GAMBIT was used to further simplify the model and to add a finite volume mesh and initial boundary conditions . The partially -premixed solver was chosen in FLUENT® with a unique incorporation of the non -premixed and premixed combustion chemistry to establish an arc and to track the flame front . Simulation results indicated a flame front propagation with a spark discharge as the ignition source . Three - and two -dimensional contour plots were used for the flame front visualization and analysis . Additional volume -averaged analysis of the discrete phase model burnout rate , species mole fraction , temperature and progress variables show track the ignition and flame propagation in the control volume . Overall , the results indicate the successful implementation of a hybrid partially -premixed combustion model , to simulate arc tracking and flame propagation in a three -dimensional enclosure .
URI: http : / /hdl .handle .net /10106 /626
Date: 2007-09-17

Citation

Exploratory Studies Of Convective Flows Due To Arc Tracking. Available electronically from http : / /hdl .handle .net /10106 /626 .

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