Validation of rhoCentralFoam for Engineering Applications of Under-Expanded Impinging Free Jets
Abstract
A numerical validation study of under-expanded impinging jet is conducted using OpenFOAM, an open-source computational fluid dynamics (CFD) library. RhoCentralFoam, a density based, compressible flow solver with a two-equation shear stress transport (SST) turbulence model is used on an axisymmetric model to reduce the computation cost. Major features of the flow were compared to an experimental study by Henderson et al., with a nozzle pressure ratio (NPR) of 4.0 and nozzle to plate spacing between 1.65-4.16. Of the features measured, the Mach diamond spacing, super-sonic core, and shear layer are all accurately predicted, while the recirculation bubble in the impingement region and acoustic phenomenon are suppressed. The model is then applied pneumatic nebulizer medical device, which generates a low-pressure vortex by confining the impingement region. Several geometric features are varied to determine their influence on the rotating vortex, of which the nozzle to plate spacing was most influential.