Online

Seksinsky, Drue

Mechanical Engineering

2020

M.S.

A computational study was conducted of axisymmetric droplet impingement on a flat surface at low droplet Reynolds numbers. The study was motivated by deposition of melted volcanic ash particles within gas turbine engines, which can pose significant safety risk for jet aircraft encountering volcanic ash clouds. The computations were performed using the combined level-set volume-of-fluid method for Reynolds numbers Re in range 0.05[less than or equal to]Re[less than or equal to]10, typical of volcanic ash impingement problems. Computational results were compared to typical assumptions for approximate droplet impact models at high Reynolds number. The computational predictions were validated using existing experimental data. The computations indicate that contact radius increases over short time in proportion to the square root of time, in agreement with short-time analytical predictions. The droplet shape was well approximated by a truncated spherical cap, which spread on the substrate surface an increasing amount as Re was increased. The axial velocity component was approximately independent of radius over most of the droplet, and the radial velocity component was observed to vary log-normally with axial distance. The dissipation rate was distributed throughout the droplet for low Reynolds numbers cases, but became increasingly localized near the contact line as the Reynolds number increased past unity.