Dynamics of Droplet Collision and Flame Motion

摘要

The present program aims to study the dynamics of droplet collision and flame-flow interaction that are of relevance to liquid-fueled turbulent combustion in propulsive devices. The investigation involves experimental, computational, and analytical components. The program recognizes the fundamental similarity between droplet collision and flame dynamics, especially from the computational viewpoint, in that both phenomena involve the tracking of deformable surfaces separating two media of vastly different densities. During the reporting period four classes of phenomena were investigated, namely: (1) The dynamics of binary droplet collision, especially on the criterion for the breaking of the inter-droplet surfaces which enables droplet merging. (2) The dynamics of droplet-film collision, especially on the influence of the film thickness in effecting droplet bouncing versus absorption. (3) The dynamics of droplet-droplet collision of dissimilar liquids, showing that the initiation of droplet internal superheating and hence microexplosion can be greatly facilitated by the presence of air bubbles entrained upon coalescence of the colliding droplets. (4) The dynamics and interaction of a freely propagating premixed flame with a vortex pair, with particular attention on the extent of flame wrinkling and flame-generated vorticity due to the generation of the baroclinic torque through the intrinsic hydrodynamic instability.