Multiphase Flows and Atomization

Multiphase flows are ubiquitous and common aerospace engineering applications for power generation and cooling. These multiphase phenomenon have to be studied carefully for improving existing or build completely new designs for increased efficiency and performance. I am interested in exploring multiphase flow phenomenon such as jets, shock-droplet interactions, droplet collision, etc.

    Jet Injection, Breakup and Droplet Formation

    The straight jet injection and the jet injection into air crossflow are two of the most common configurations used in engineering applications. Jet breakup is an important phenomenon as jet breakup, ligament and droplet formation and atomization and sometimes vaporization are needed for combustion. These are critical phenomenon for combustors and afterburners and their design has to include a detailed study on jet breakup and atomization behavior. The straight jet configuration shows the mushroom cap formation and the ligament formation followed by droplet formation. The jet column becomes unstable after sometime. The jet in air crossflow shows the windward side Kelvin-Helmholtz type instabilities along with the bending of the jet to align with the crossflow. The dropelet formation is more significant as the crossflowing air has a higher momentum causing jet breakup and droplet formation. Droplet statistics can give good insight into the process for inclusion in design studies.

    Jet configurations, showing jet primary and secondary breakup with ligament and droplet formations and atomization.

    Binary Collision of Molten Sand Particles

    Molten sand particles are often encountered in engines working in harsh environments. Sand can be ingested and the high temperatures can result in the melting of sand particles, which can be modeled as droplets. The simulations below show how the molten sand particles behave. Two configurations are shown - one for equal droplets at offset distance between droplet centers, and one for unequal droplets at offset distance between droplet centers. The drops coalesce for either configuration leading to larger droplet formations. Studying this type of behavior is necessary for improving designs to avoid catastrophic failure.

    Time evolution of binary collision of equal and unequal molten sand particles, colliding in an offset configuration.

    Other Multiphase Flows of Interest

    I have conducted numerical simulations on different types of multiphase flows, such as - binary collision of dodecane droplets and the classic Rayleigh-Taylor instability due to density variation in liquids.

    1. J. Qian and C.K. Law, "Regimes of coalescence and separation in droplet collision" Journal of Fluid Mechanics, Volume 331, Jan 1997. doi: https://doi.org/10.1017/S0022112096003722.

    Binary collision of equal dodecane droplets, and the Rayleigh-Taylor instability due to varying densities in a liquid.

Relevant Publications

  1. Tripathi M, Ganti H, Khare P., “Interaction between Shock Waves and Droplet Clusters: Interfacial Physics”, ASME Journal of Fluids Engineering, May, 2022. doi: https://doi.org/10.1115/1.4054181.

  2. Tripathi M, Ganti H, Khare P., “Interaction between Shock Waves and Droplet Clusters: Interfacial Physics and Fragmentation Behavior”, Institute for Liquid Atomization and Spray Systems, ILASS Americas 2021 Virtual Conference, May, 2021.

  3. H. Ganti, P. Khare, and L. Bravo, “Binary collision of CMAS droplets — Part II: Unequal sized droplets”. Journal of Materials Research, Focus Issue - Sandphobic Thermal/Environmental Barrier Coatings for Gas Turbine Engines, December, 2020. doi: https://doi.org/10.1557/jmr.2020.153.

  4. H. Ganti, P. Khare, and L. Bravo, “Binary collision of CMAS droplets — Part I: Equal sized droplets”. Journal of Materials Research, Focus Issue - Sandphobic Thermal/Environmental Barrier Coatings for Gas Turbine Engines, December, 2020. doi: https://doi.org/10.1557/jmr.2020.138.