ID 367

Eulerian / Lagrangian Simulation of Aerated-Liquid Injection into Subsonic and Supersonic Crossflows

 

Abstract:

Aerated-liquid or ‘barbotage’ atomization initiates primary breakup by injecting a small amount of gas into a co-flowing liquid and then expanding the mixture through a small-orifice nozzle. At high gas-to-liquid mass ratios, the result is a highly-turbulent two-phase flow that can be characterized as having a core-annular structure. The core is populated by fine-scale droplets, shed from the annular liquid film by aerodynamic forces. The injection of the two-phase flow into a crossflow environment results in the breakup of the annular liquid sheet followed possibly by secondary droplet breakup mechanisms. An Eulerian homogeneous mixture model, evolved as a large-eddy simulation, will be combined with a parallel Lagrangian droplet-tracking algorithm to simulate the evolution of the initially dense spray. Factors included in the droplet-tracking model include dense-spray effects on drag forces, secondary droplet breakup mechanisms, and separate initial droplet size distributions for core and annular regions. Results will be obtained for two cases: one involving ‘out-in’ aerated liquid injection into a Mach 0.3 subsonic crossflow and the other involving aerated-liquid injection into a Mach 2.0 supersonic crossflow. Predictions will be compared with confocal X-ray fluorescence measurements for the subsonic crossflow experiments and with phase Doppler particle anemometry and laser-sheet illumination data for the supersonic crossflow experiments.