59421 - Localized Breakup Instabilities for a Liquid Fuel Jet in Crossflow 

Liquid fuel jet in Crossflow (LJIC) is significant to the aviation industry since it is a vital technique used for atomization. The hydrodynamic instability mechanisms which drive the primary breakup of a transverse jet were investigated using modal and traveling wavelength analysis.. This study highlights the primary breakup mechanisms for three aviation fuels: Jet-A, JP-5, and JP-8. Mathematical decomposition techniques known as POD (Proper Orthogonal Decomposition), and MrDMD (Multi-Resolution Dynamic Mode Decomposition) are used together to identify dominant instability flow dynamics associated with the primary breakup mechanism. Implementation of the MrDMD method deconstructs the nonlinear dynamical systems into multiresolution time-scaled components that capture the intermittent coherent structures. The MrDMD, in conjunction with the POD  method, is applied to data points taken in the multi-modal and shear spray breakup regimes. Both spray breakup regimes are prevalent within the operating conditions of air-breathing engines. The dominant frequencies of both breakup regimes are extracted and identified. These coherent structures are classified with an associated time scale and Strouhal number. Furthermore, characterization of the traveling column and surface wavelengths are conducted and associated with an atomization model which predicts Sauter Mean Diameter associated to the dominant traveling wavelengths. A comparative fuel analysis of coherent structures and traveling wavelengths identify effects from physical property differences. Traveling wavelengths classify the instability mechanisms convolved within the spray regimes, data within the multi-modal breakup demonstrate dominant instability is driven from Rayleigh -Taylor instability. Similarly, the shear breakup consists of a combination of both Rayleigh-Taylor and Kelvin Helmholtz instability.