Reduced-Order Acoustic Prediction Tool for Ducted Fan Noise Sources Including Inflow Distortion and Turbulence Ingestion

In response to NASA SBIR topic A1.02, the team of Techsburg, AVEC, and aircraft developer Ampaire have begun implementation of a reduced-order acoustic prediction tool for ducted fan noise sources including inflow distortion and turbulence ingestion.nbsp; Named the ldquo;Installed Ducted-Fan Noise Modelrdquo; (IDFNM) and branching from Techsburg/AVECrsquo;s recognized collaborative work in noise modeling for pusher propellers for defense and commercial customers, this tool will offer early-stage design support for installed ducted fan-rotor propulsion systems by capturing the aerodynamic unsteady loading and noise sources resulting from inflow distortion and unsteadiness ndash; sources of significant importance for the emerging highly-integrated propulsion-airframe concepts such as boundary layer ingesting fans.nbsp; Phase I work positioned the team to use Ampairersquo;s first-generation, aero-efficient TailWind electric aircraft as a demonstrator for novel acoustic prediction tools. nbsp;Building on the Phase I upgrades to the existing NASA codebase V072, Phase II work will see targeted development of a reduced-order prediction tool for turbulence ingestion noise (TIN), a current technical gap in NASA/industry capability.nbsp; Leveraging extensive background in the field of turbulence ingestion from academic partners Drs. William Devenport and Nathan Alexander, this tool will derive inflow turbulence statistics by appropriate scaling of correlation functions as measured on four canonical geometries.nbsp; Combined with accepted blade response models and propagation via Greenrsquo;s function to the far-field, the result will be a first-of-its-kind prediction tool accessible at low computational cost.nbsp; Milestones throughout the work will see the acoustic prediction tool validated in the state-of-the-art anechoic wind tunnel at Virginia Tech.nbsp; nbsp;The deliverable of this Phase II work is the integrated low-order noise prediction softwarenbsp;quot;Installed Ducted-Fan Noise Modelrdquo; which ultimately will be commercialized.