Research Projects

Interacting sprays are often encountered in many industrial applications such as furnaces, internal combustion engines, rocket engines etc. Spray-to-spray impact often leads to collision between droplets that always changes the velocity, and often the size of the colliding droplets. Only a few collisions during a droplet’s lifetime are required to completely change its behavior, hence, it plays a crucial role in droplet dispersion. As the physical phenomenon involved in spray interaction is quite complex due to the wide range of droplet size distribution and dynamic behaviour of individual droplets, research has been mainly focused on binary droplet collisions, while understanding the consequence of droplet collision on droplet dispersion in sprays is still lacking. In addition, spray interaction studies under supercritical conditions, which are relevant to applications such as rocket engines, are rare. In liquid propellant rocket engines, numerous injectors are arranged on a plate often called as the shower head or injector plate, at the inlet of the thrust chamber. The sprays generated from the individual injector elements interact with each other and produce the necessary oxidiser-propellant mixture that further undergoes combustion in the thrust chamber and eventually produces thrust. The individual sprays and the interaction between them influence the distribution/mixing of the oxidiser/propellant, evaporation rate of the liquid component, combustion, and heat release within the thrust chamber. Unwanted effects in heat release often impact the structural health of the thrust chamber leading to damage of components and also contribute to combustion instabilities that are very detrimental to the performance of the engine. In this work, we consider Gas Centred Swirl Coaxial (GCSC) injectors which are employed in semi-cryo rocket engines. Although spray characterization in individual GCSC sprays has been extensively reported in the past, however, the interaction between such sprays, which typically happens in the thrust chamber, has not been studied with the same vigour. A fundamental approach towards characterization of interaction of sprays between adjacent or multiple GCSC elements is missing. The aim of this proposal is to make a systematic investigation on the spray interaction under super-critical and non-reacting conditions using optical techniques. Study of the interaction between sprays from multiple GCSC elements mounted in typical injector plate layout patterns is being proposed to better understand the evolving spray. Various optical diagnostics will be employed to study the atomization and spray characteristics qualitatively and quantitatively. Such knowledge would not only help us in establishing or identifying the relationship/contribution of spray interaction parameters to mixing and evaporation but also in modeling the spray process.