The objective of this proposal is the development and demonstration of a cost-effective high-fidelity aeroacoustic design tool for future commercial supersonic nozzle designs and installations. Although eddy-resolving CFD methods for computing high-speed jet noise are available, such methods are computationally expensive and are currently deemed impractical for use in a design optimization loop. On the other hand, the prediction of turbulence generated noise using the Reynolds-Averaged Navier-Stokes (RANS) equations provides a less accurate but more cost-effective approach for practical design problems, wherein the turbulence length and time scales needed to model the local noise source terms can be extracted from the RANS turbulence model solution, as performed by the NASA JeNo code. The objective of this project is to develop a tightly coupled practical RANS-based jet-noise aeroacoustic analysis and design optimization capability which can be leveraged by government and industrial customers to better understand and design efficient propulsion systems that meet well defined and accepted noise metrics. The approach consists of developing an exact discrete adjoint method for a tightly coupled RANS-acoustic prediction method in order to provide sensitivities for gradient-based aerodynamically constrained acoustic optimizations. This capability will be demonstrated on realistic nozzle configurations including single and dual stream chevron nozzles, and marketed to government and industrial customers in the aerospace industry.
The proposed technique will provide a novel tool for enabling the design of supersonic nozzles optimized for reduced far-field noise signatures. This is an important application area for NASA ARMD, since the acceptance of future commercial supersonic aircraft depends heavily on reduced environmental impact. The optimization approach will be developed in a modular fashion and will be easily transferable to NASA in-house RANS codes which incorporate an adjoint capability such as FUN3D.
The jet noise optimization capability will be incorporated into the simulation and design tools developed by Scientific-Simulations and will be marketed to existing and new customers. The approach is seen as a natural extension of the various multidisciplinary adjoint capabilities already developed at Scientific Simulations, and will enable new applications in high-speed jet noise optimization.