SBIR-STTR Award

In response to NASA SBIR topic A1.02 Quiet Performance – Propulsion Noise Reduction Technology, the team of Techsburg, AVEC, and Ampaire proposes implementation and design application of a low-order noise modeling tool for installed ducted fan-rotor aerodynamic and acoustic analysis. Named the “Installed Ducted-Fan Noise Model” (IDFNM), and following after Techsburg/AVEC’s work in noise modeling for pusher propellers, this tool will offer early-stage design analysis support for installed ducted fan-rotor propulsion systems by capturing the aerodynamic unsteady loading and noise sources resulting from inflow distortion or non-uniform inflow. This tool is well suited for highly integrated and innovative propulsion airframe integration concepts, such as boundary layer ingesting fan configurations. Application of this tool will focus on a highly-efficient design for Ampaire’s TailWind electric aircraft. In collaboration with Ampaire, Techsburg and AVEC will work to design an optimized first-generation BLI ducted fan for the TailWind passenger aircraft. During Phase I, Techsburg and AVEC will work on design tool maturation, and also conduct a propulsor design trade study, complete with aerodynamic and acoustic predictions, for the TailWind aft-mounted, boundary layer ingesting ducted fan. Phase II work will include an anechoic wind tunnel test program for validation of prediction tools over a range of operating conditions and the delivery of an integrated low-order noise prediction software package for the "Installed Ducted-Fan Noise Model”. Potential NASA Applications The ultimate deliverable of the proposed work is the "Installed Ducted-Fan Noise Model” (IDFNM) which will contribute to NASA's Advanced Air Transport Technology Program and related work as it seeks to improve on conventional aircraft performance and noise emissions. Furthermore, this proposal features focused design work on the Ampaire Tailwind, an aircraft with a BLI ducted fan propulsor in the 500-kW class that is aligned well with NASA’s development goals and X-57 roadmap. Potential Non-NASA Applications Noise from non-uniform flow ingestion into rotating fans is a fundamental engineering problem. The application of inflow distortion noise modeling has many uses apart from ducted fan design and development. These applications include HVAC fan systems, cooling fans, turbomachinery, marine propulsion, impeller/blower cage designs, and commercial products that utilize blowers and fans to move air. These will be investigated as potential markets for the technology and design approach.

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. Named the “Installed Ducted-Fan Noise Model” (IDFNM) and branching from Techsburg/AVEC’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 – sources of significant importance for the emerging highly-integrated propulsion-airframe concepts such as boundary layer ingesting fans. Phase I work positioned the team to use Ampaire’s first-generation, aero-efficient TailWind electric aircraft as a demonstrator for novel acoustic prediction tools. 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. 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. Combined with accepted blade response models and propagation via Green’s function to the far-field, the result will be a first-of-its-kind prediction tool accessible at low computational cost. Milestones throughout the work will see the acoustic prediction tool validated in the state-of-the-art anechoic wind tunnel at Virginia Tech. The deliverable of this Phase II work is the integrated low-order noise prediction software "Installed Ducted-Fan Noise Model” which ultimately will be commercialized. Potential NASA Applications (Limit 1500 characters, approximately 150 words) This SBIR targets a technical gap in the reduced-order acoustic prediction toolset of NASA/industry. The progress represents a low-risk, high-reward solution to NASA’s need for growth in modeling acoustic sources for propulsors in highly unsteady inflows within the Advanced Air Transport Technology Program. Post-Phase II stakeholders include NASA Glenn (for commercialization and integration of acoustic code with existing NASA-aligned tools) as well as all NASA/industry partners pursuing state-of-the-art, high efficiency, low noise aircraft. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) The forthcoming "Installed Ducted-Fan Noise Model” tool will be marketed as a reduced-order prediction tool for industry/academia, lending itself to any number of nascent aircraft configurations including Ampaire’s Tailwind design. State-of-the-art inflow distortion noise modeling may also find inroads in ducted lift fans, HVAC fans, turbomachinery, marine propulsion, and impeller/blower cages.