Local solutions for characterizing the dynamics of liquefying fuels in slab experiments

The focus of this study is to analyze the mass loss over two distinct regions of the slab—the leading edge which is dominated by entrainment and downstream which is dominated by the film flow. Experiments are performed in 200∘C, high speed air using paraffin wax slabs. For the leading edge, a force balance is performed using shear stress data from direct numerical simulations (DNS) to estimate a lobe height and is compared to the flat plate assumption and experimental data. The paraffin samples have 90∘, 45∘, and 20∘ leading edge angles to compare shear stress profiles for different inlet angles. The error in the height approximation is below 20% for the DNS shear stress profile case while the flat plate assumption can exceed 80%. For estimating the film mass loss rate, 4 quasi-steady models are compared by calculating the height under different assumptions and comparing to experimental thermocouple data for a sample with a 45∘ leading edge. It is found that the height can be non-dimensionalized, which can aid future predictions of the film thickness. Finally, the film mass loss rate is calculated and divided by the total mass loss rate from the experiment to show film loss percentages of 46–64%.