New Paper in AIAA Journal Published: Local Burning Rates and Heat Flux for Forced Flow Boundary-Layer Diffusion Flames

Building on our previous work with buoyant flows, this new paper details measurements of heat fluxes and local burning rates over liquid fuel wicks under forced flow. These laminar flames are interesting from a theoretical viewpoint, where the classical Emmons’ solution typically describes them well. The influence of buoyancy, described by the Richardson Number, can be quantified here where two separate attachment points form and traditional solutions start to fail. The detail of the measurements provided will hopefully aid modeling efforts in the future. Our next step is to move these measurement techniques to more practical fuels and regimes (turbulent).


A methodology based on the Reynolds analogy was developed earlier that allowed for the estimation of local mass burning rates and heat fluxes in free-convection laminar boundary-layer diffusion flames. In this study, the relationship was examined in a forced-convective environment using methanol as a liquid fuel. The gas-phase temperature profiles across the laminar boundary layer with a methanol diffusion flame established over it were measured with the freestream air flowing parallel to the condensed fuel surface. Local and averaged mass burning rates were measured along with shear stresses at the fuel surface. The fuel consumption rate and flame lengths were observed to increase monotonically with an increase in the freestream velocity. Although the initial study was taken in the laminar regime, further extensions of the technique could be applicable to turbulent boundary-layer combustion in propulsion-oriented research.

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