Interference effects during burning of tandem porous spheres in mixed convective environment

The interference effects during the burning of a binary tandem droplet arra y in a mixed convective environment have been studied both theoretically an d experimentally for the upward airflow configuration. In the theoretical m odel, the flow and transport equations have been solved subject to the assu mptions of constant properties (except for density) and infinite rate kinet ics, by the use of the finite element method. The gas density has been trea ted as a variable, only for evaluating the buoyancy force contribution, and it has been determined through the ideal gas mixture assumption, A porous- sphere facility has been employed for simulating experimentally the burning characteristics of a fuel droplet array with fixed separation distance. Th e measured mass burning rates for both the spheres and the observed dame sh apes are in excellent agreement with the corresponding theoretical predicti ons. The burning rate of the rear droplet is considerably less than that of the front droplet or an isolated droplet, for smaller separation distances . For larger separation distances, the burning rate of the rear droplet is of the same order as the front droplet, and it is sometimes even larger tha n that of the isolated droplet. The rate of burning of the front droplet mi ldly varies with separation distance, and it is approximately equal to that of an isolated droplet. The dame of a tandem binary droplet system is obse rved to be pushed away from the axis due to the presence of the second drop let.