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The laminar burning velocity of pure and diluted high-temperature propane−air mixtures is extracted from the planar flames stabilized in the preheated mesoscale diverging channel. The experiments were carried out for a range of equivalence ratios of 0.7 ≤ Φ ≤ 1.3 and mixture temperatures of 370−650 K. The effect of dilution using CO 2 and N 2 gases (up to 40%) on C 3 H 8 −air burning velocity is also studied. Experiments complimented with computational studies of experimental conditions confirm that the stabilized flames were planar in both transverse and depth directions, and the burning velocity with heat flux in the present case is nearly equal to the adiabatic burning velocity. The detailed uncertainty analysis shows the accuracy of the present measurement within ±5%. Computational predictions of burning velocity and detailed flame structure were performed using PREMIX code. The present experiments are successfully validated against existing experimental and computational results. The peak burning velocity was observed for slightly rich mixtures even at higher mixture temperatures. The minimum value of the temperature exponent is observed for slightly rich mixtures. The burning velocity was observed to decrease with the dilution of inert gases. The addition of CO 2 shows a pronounced decrease in the burning velocity, as compared to N 2 .

The present work reports the measurement of the laminar burning velocity of liquefied petroleum gas (LPG)−air mixtures at high temperatures using the planar flame propagation mode appearing in the preheated mesoscale diverging channel. The experiments were carried out for a range of equivalence ratios, 0.7 ≤ Φ ≤ 1.3. The present data for LPG−air mixtures are reported for a temperature range of 370−650 K in comparison to maximum mixture temperatures of 400 K reported in the literature. Experimental studies complimented with computational studies for conditions similar to present experiments confirm that the effect of heat loss from flame to channel walls on burning velocity is minimal and measured burning velocities are nearly equal to adiabatic burning velocity. The stabilized flame is nearly flat in both transverse and depth directions. The power law form of correlations from present experiments help in understanding the variation of laminar burning velocity with mixture temperatures and equivalence ratios. An increase in mixture temperature significantly enhances the burning velocity. Maximum burning velocity is obtained for slightly rich mixtures, unlike for the highly rich mixtures reported in the literature. A minimum value of the temperature exponent is observed for slightly rich mixtures.

The measured and computed laminar burning velocities of methane–air mixtures at higher mixture temperatures are reported in this paper. The experiments and computations were performed for a wide range of mixture temperatures and equivalence ratios. The unburned mixture temperature ranges from 370 to 650 K. Computational predictions of burning velocities were carried out with GRI-Mech 3.0, San Diego mechanism, and Konnov mechanism for methane–air mixtures. The measured burning velocities match very well with the numerical predictions for all mixture temperatures and existing experimental results for mixtures at ambient temperature. Another contribution of the present work is the variation of the measured power-law temperature exponent with mixture equivalence ratios. The maximum burning velocity (even at high mixture temperatures) and minimum temperature exponent magnitudes were observed to exist for slightly richer mixtures.