The proposed SBIR Phase I & II programs will lead to the validation of a state-of-the-art Large Eddy Simulation (LES) model, coupled with a Ffowcs-Williams-Hawkings (FW-H) farfield acoustic solver, for supporting the development of advanced engine concepts, including innovative flow control strategies for attenuation of their jet noise emissions. The LES/FW-H model will be simultaneously validated against matched sets of flowfield and companion acoustic data acquired recently at NASA/GRC for round nozzles. The flowfield validation will include detailed comparisons against imagery, mean flow measurements and turbulence statistics. The end-to-end capability of the LES/FW-H noise prediction model will also be demonstrated by applying it to high aspect-ratio rectangular nozzle designs, proposed for testing at NASA GRC under the Fundamental Aeronautics Program. This critical validation will provide the foundation for proceeding to application of this innovative methodology in supporting the design and optimization of control concepts, e.g. chevrons, slot jets, fluidic chevrons, etc., as well as ultimately performing predictions of noise emissions from full-scale, realistic nozzles with complex exhaust flowpaths, airframe/propulsive jet interactions, etc.