Physics-Based Systems Level Jet Noise Modeling

Abstract

A jet noise prediction tool has been developed for predicting jet noise and for performing system level trade studies within propulsion system analyses. This tool, NozzleDB, incorporates Jet3D, a RANS-based jet noise prediction scheme based on Lighthill’s Acoustic Analogy theory, to predict the acoustic characteristics of exhaust nozzles. NozzleDB integrates a system of proven tools into a single, streamlined process that creates a CFD mesh for the desired exhaust system plume, performs a CFD analysis using WIND, and processes the results through Jet3D to predict the acoustic signature. This process offers relatively quick results compared to those obtained from alternative methods like LargeEddy Simulations (LES) or Direct Numerical Simulation (DNS), making it advantageous for use in system level studies to minimize jet noise while maintaining high levels of thrust performance. A significant feature of the NozzleDB code is that it utilizes the nozzle exit profile to provide a method of assessing jet noise from the fundamental aerodynamics of the nozzle, allowing acoustic studies to focus on the aerodynamic sources of jet noise rather than the geometries that cause them. Once the desired aerodynamic characteristics are defined, then the nozzle design can be directed to achieve them. This approach provides reductions in design cycle time for developing acoustic attenuation features in exhaust nozzles.