Detailed Validation of Numerical Simulations of Air-blast Spray Atomization against Experimental Back-lit Images and Radiographs
Résumé
Sprays appear in a variety of industrial applications ranging from powder production used in additive manufacturing to fuel nozzles. Air-blast atomization is a specific injection strategy whereby a high-speed gas shears and destabilizes a low-speed liquid which causes a cascade of instabilities leading to the creation of a spray. The flow physics around the nozzle are challenging to quantify and complex. Inside the nozzle, traditional PIV and hot-wire methods cannot be used to measure turbulence and boundary layer growth and at the nozzle exit, radiographs and back-lit images show complex time-varying wetting and contact line dynamics. In this study, we explore different computational strategies to model these flow physics and validate them against equivalent path length data (EPL), a measure of the liquid depth along a line-of-sight. Further downstream, thin liquid structures that fall below the mesh size are prone to numerical break-up and as a consequence, we employ a thin-film model to improve agreement. We make use of a multi-block simulation strategy to address the multi-scale nature of atomization. Finally, using these models, we make direct comparisons of quantities such as the liquid intact length.
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