Design Optimization and Analysis of Advanced Exhaust Systems

Cascade Technologies and its collaborators from the Florida State University and Stanford University propose to develop a robust computational framework to enable geometrical optimization of complex non-axisymmetric exhaust systems with controlled accuracy and low computational cost. In this framework, Reynolds-averaged Navier-Stokes (RANS) surrogates will be constructed based on extensive databases from high-fidelity large eddy simulations (LES) of the exhaust system and jet plume. The RANS surrogates will then be used to efficiently explore the design space considered. Ultimately, the final optimized configuration will be once again analyzed using the LES tools to verify the performance gains predicted by the surrogate. In addition, a companion experimental investigation will provide the basis for a detailed validation and further confidence in the computational predictions. A coordinated Phase I plan is presented, which includes experimental measurements, LES predictions and RANS optimization for a rectangular nozzle. In phase I Option, the procedure will be extended to a SERN-inspired nozzle where a ramp downstream of the rectangular nozzle exit is explicitly included in the computations and experiments. Research directions and plans are outlined for Phase II work, with focus on fluid-structure coupling, introduction of robustness principles within the optimization cycle and innovative non-intrusive techniques for exhaust internal flow measurements.