UNDERSTANDING THE ROLE OF HEAT RECIRCULATION IN ENHANCING THE SPEED OF PREMIXED LAMINAR FLAMES IN A PARALLEL PLATE MICRO-COMBUSTOR

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dc.contributor.advisorCadou, Christopher Pen_US
dc.contributor.authorVeeraragavan, Ananthanarayananen_US
dc.contributor.departmentAerospace Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2009-10-06T06:33:20Z
dc.date.available2009-10-06T06:33:20Z
dc.date.issued2009en_US
dc.description.abstractThis dissertation investigates the role of heat recirculation in enhancing the flame speeds of laminar flames stabilized in a parallel plate reactor by: 1) developing analytical models that account for conjugate heat transfer with the wall and 2) making measurements of temperature profiles in a simulated microcombustor using non-intrusive FTIR spectroscopy from which heat recirculation is inferred. The analytical models have varying degrees of complexity. A simple heat transfer model simulates the flame by incorporating a concentrated heat release function along with constant temperature wall model. The next level model accommodates conjugate heat transfer with the wall along with a built in heat loss model to the environment. The heat transfer models identify the thermal design parameters influencing the temperature profiles and the Nusselt number. The conjugate heat transfer model is coupled with a species transport equation to develop a 2-D model that predicts the flame speed as an eigenvalue of the problem. The flame speed model shows that there are three design parameters (wall thermal conductivity ratio ( &kappa ), wall thickness ratio ( &tau ) and external heat loss parameter ( Nu<sub>E</sub> )) that influence the flame speed. Finally, it is shown that all these three parameters really control the total heat recirculation which is a single valued function of the flame speed and independent of the velocity profile (Plug or Poiseuille flow). On the experimental side, a previously developed non-intrusive diagnostic technique based on FTIR spectroscopy of CO2 absorbance is improved by identifying the various limitations (interferences from other species, temperature profile fitting, ... etc) and suggesting improvements to each limitation to make measurements in a silicon walled, simulated microcombustor. Methane/Air and Propane/Air flames were studied for different equivalence ratios and burning velocities. From the temperature profiles it can be seen that increasing the flame speed pushes the flames further up the channel and increases the combustors inner gas and outer wall temperatures (measured using IR thermography). The temperature profiles measured are used to make a 2-D heat recirculation map for the burner as a function of the equivalence ratio and burning velocity. The experimental results are compared to the analytical models predictions which show a linear trend between flame speed and heat recirculation.en_US
dc.format.extent4766041 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/9630
dc.language.isoen_US
dc.subject.pqcontrolledEngineering, Aerospaceen_US
dc.subject.pquncontrolledFlame speeden_US
dc.subject.pquncontrolledFT-IR Spectroscopyen_US
dc.subject.pquncontrolledHeat Transferen_US
dc.subject.pquncontrolledMicro-combustionen_US
dc.subject.pquncontrolledNon-intrusive diagnosticsen_US
dc.subject.pquncontrolledTemperature measurementsen_US
dc.titleUNDERSTANDING THE ROLE OF HEAT RECIRCULATION IN ENHANCING THE SPEED OF PREMIXED LAMINAR FLAMES IN A PARALLEL PLATE MICRO-COMBUSTORen_US
dc.typeDissertationen_US

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