Comparison between experimental measurements and numerical predictions of internal temperature distributions of a droplet vaporizing under high-temperature convective conditions

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The current study uses the data produced in a recent experimental investigation to evaluate and validate the methods employed in a detailed numerical model that simulates liquid-fuel droplet vaporization in a high-temperature, laminar, convective environment. The experimental study, which produced vaporization rates and internal temperature distributions of large, hydrocarbon, suspended droplets vaporizing at atmospheric pressure, involves Reynolds numbers up to 100, representative of practical situations of interest. A series of comparisons is performed between model predictions and experimentally measured relevant quantities. The agreement between experiment and theory on the temporal variation of certain temperatures in the droplet interior is favorable. The model predicts slightly higher vaporization rates, as indicated by lower values of the droplet diameter at corresponding instances of the droplet lifetime. The predicted temperature distributions in the droplet interior are also in good agreement with those measured experimentally throughout the droplet lifetime. To this end, both experiments and modeling agree on the establishment of internal circulation in liquid droplets exposed to laminar, high-temperature, gaseous flows. Agreement is also established on the relative insensitivity of the droplet temperature distributions when a considerable increase of free-stream momentum occurs. On the other hand, even though the model predictions show that substantially increased liquid viscosities do slow down the establishment of the liquid-phase motion, the experimental observations conclude that substantially higher liquid viscosities eliminate the liquid-phase motion entirely. The overall agreement between model predictions and experimental measurements shows that modeling can be a reliable tool in examining liquid-droplet convective evaporation under conditions that are not easily reproduced experimentally.