NUMERICAL INVESTIGATION OF DROPLET DEFORMATION UNDER PULSATING FLOW

The droplet motion, deformation and breakup is widely investigated as it is prevalent in many applications such as IC engines, gas turbines, rocket engines, medical devices and airborne disease transmission. A comprehensive body of experimental and numerical studies exists for droplet subjected to continuous gas streams. However, in certain situations like thermoacoustic instabilities in rocket engines and gas turbines, the droplet is subjected to a pulsatile flow, and droplet behavior under these conditions is investigated in this work. Numerical simulations are performed using the finite volume technique, applying the Volume of Fluid (VOF) method to track the droplet-gas interface effectively. The adaptive mesh refinement technique effectively reduces cell count and, hence, the computational cost. The 3-D simulations for steady flow are validated with the experimental data. Next, the pulsatile flow is simulated using a time-dependent sinusoidal gas velocity and the effects of amplitude and frequency on breakup time and droplet evolution are studied. The 3-D pulsatile simulation compares well with the 2-D pulsatile simulation, which is computationally much less expensive and hence used extensively for parametric studies. The breakup time is compared with that of uniform flow conditions. The pulsation of the crossflow stream was found to accelerate the breakup process. The pulsation amplitude is found to affect more than the frequency of flow.