Description: ATA Engineering, Inc. (ATA) proposes a Phase II-E SBIR project enhance capabilities and methods in its Continuous-scan Acoustic Measurements (CSAM) toolkit a to reduce test time and improve data quality in the NASA Glenn Research Center (GRC) 9x15-foot Low Speed Wind Tunnel (LSWT). The enhanced tools will be based on codes prototyped during the Phase II SBIR project to perform fan-inlet- and fan-outlet-noise source separation analytically using data acquired by the LSWT’s continuous-scan microphone. A conventional way to separate fan-inlet and fan-outlet noise in the 9′ × 15′ LSWT has been through use of a barrier wall which blocks line of sight fan-outlet radiating noise to measure only the fan-inlet contribution. However, use of a barrier wall may effectively double the number of test points required to adequately characterize a fan, adding cost burden to an already expensive test campaign. ATA’s CSAM methods would use reference sensors such as stationary microphones or a shaft tachometer signal to extract high-spatial-resolution partial fields to analytically separate the sources from the empty tunnel configuration alone, i.e. without the use of the barrier wall. This may effectively halve the number of required test points. The goal of the Phase II-E is to produce an advanced version of the CSAM toolkit that is usable by the 9x15 LSWT facility for source separation. Two different source modeling assumptions (one developed by ATA, and one by our partner UC Irvine) will be included and verified using test data from the recently upgraded wind tunnel. The advanced capability will allow NASA to efficiently process data for future wind tunnel industry customers (e.g., General Electric, Pratt and Whitney, Honeywell) to reduce testing costs and improve data quality. A practical objective of this project is to demonstrate the potential for a 30%–50% decrease in the time and cost for testing a given set of configurations.

Benefits: Elimination of barrier wall testing reduces test time and cost, and allows for more comprehensive studies in facilities like the NASA GRC LSWT. The extended capability of CSAM to support propulsion airframe aeroacoustic (PAA) studies will also aid NASA to develop next-generation airframes and propulsion systems at other facilities that use engine simulators such as the Unitary Plan Wind Tunnels, and the 14′ × 22′ subsonic tunnel and Structural Acoustics Loads and Transmission (SALT) facility.

Non-NASA applications of this high-resolution technology include air mobility vehicle noise, automotive and heavy equipment noise, consumer audio, and factory equipment. Many of these applications rely on source localization and separation using acoustic cameras, implying immediate commercialization opportunities for the superior diagnostics resulting from this effort.