The Onset of Hydrodynamic Instability in Dual Orifice Atomizers

This paper deals with the numerical investigation of inner flow instability in pressure swirl atomizer with a “nozzle within a nozzle” configuration. It begins with an overview of the high fidelity hybrid RANS-LES approach for interface capturing of turbulent multiphase breakdown process. This was followed by a brief discussion on the underlying physical mechanism of the unstable mixing and the transition of this action to Kelvin Helmholtz waves. Three new practical guidelines for instability evaluation were brought to the attention of the readers; flux-based estimation for the time variation of cone angle, sheet deformation ratio and a mathematical analysis of stability based on the standard deviation of the time fluctuating flow characteristics. The combination of these complementary methods can be used to accurately identify the onset of flow instability. Derived from simple theoretical foundations, these methods have the potential to provide practical benefits for the performance assessment of different injector configurations in industrial applications.