International Journal of Heat and Mass Transfer, Vol.47, No.8-9, 2029-2035, 2004
Interactive influences of convective flow and initial droplet diameter on isolated droplet burning rate
In quiescent ambiences the burning rate of an isolated liquid fuel droplet varies with the droplet's initial diameter d(0) due to the close surrounding of the droplet in the lame and the subsequent strong action of flame heat, in balance with its loss to ambience, on burning. Suppressing the influence of d(0) on burning rate was recognized in this communication through burning the droplet in a forced convective flow that sweeps the flame off the droplet to weaken the action of flame heat on burning. The d(0)-dependent k(0), however, affected the correlation k = k(0) (1 + C . Re-0.5) for the burning rate in convective flows, where k(0) and k are the burning rate constants, respectively, in the equi-temperature quiescent and convective-flow ambiences, and Re is the flow's Reynolds number with respect to d(0). Different correlation constants C were acquired when using different d(0) and its corresponding k(0) to fit the correlation. In hot conditions (633 K in this article) k(0) is bigger for larger d(0), causing a smaller constant C when taking a larger d(0) for the correlation. Against this, k(0) is lower for larger d(0) in room-temperature ambiences, which resulted in the mutual compensation of the effects from k(0) and d(0) on C such that C is basically independent of the values of d(0) and k(0). Besides, the communication showed that C was larger for the gas flow with a higher temperature, revealing an increase in the effect of Re on burning with raising the gas temperature. (C) 2003 Elsevier Ltd. All rights reserved.