Other functions - task order - statement of work (SOW) task title: microphone array based measurements of noise from a leading-edge slat 1.0 introduction/background: nasas subsonic fixed wing…

Other functions - task order - statement of work (SOW) task title: microphone array based measurements of noise from a leading-edge slat 1.0 introduction/background: nasas subsonic fixed wing project conducts research with the goal of improving prediction methods and technologies towards lower aircraft noise, lower emissions, and higher performance of subsonic aircraft for the next generation air transportation system. Development of improved prediction methods and technologies for a reduced noise signature is, therefore, one of the important focal areas for the project. To that end, the project strategy includes provisions for novel test methods and validated prediction tools that can be used to improve system tradeoffs for advanced concepts capable of meeting longer-term noise goals. Specifically, foundational research is performed in the project to establish validation data for computational tools and to develop noise prediction and reduction technologies for propulsive (i.e., engine related) and airframe noise sources. With the advent of quieter, ultra-high-bypass-ratio engines, flow unsteadiness in the vicinity of various airframe components has emerged as an important contributor to the overall noise signature of subsonic commercial transports during their landing approach. The major sources of airframe noise include high-lift devices (i.e., leading-edge slat and trailing-edge flaps) and the aircraft undercarriage (i.e., landing gear). NASA has an active program of research related to each of these noise sources. In the context of slat noise, NASA s langley research center is engaged in a coordinated series of investigations that combine high-fidelity numerical simulations and detailed wind tunnel measurements of a generic, unswept, 3-element, high-lift configuration (GFI items 5.1-5.5). The goal of these investigations is to provide a validated predictive capability that would enable the identification of the dominant noise source mechanisms and, ultimately, help develop physics inspired concepts for reducing the far-field acoustic intensity. The experimental component of this research has focused on a generic, unswept, 3-element, high-lift configuration. The 30P30N configuration, designed by mcdonnell-douglas (now boeing), has been used for various measurements of the unsteady flow near the slat in nasas basic aerodynamic research tunnel (bart). Primary data obtained thus far includes particle image velocimetry (PIV) measurements of the unsteady flow field within the slat cove and in the vicinity of the slat trailing edge. Both planar and stereo PIV measurements have been obtained to characterize the planar and cross-plane structures within this flow. This data has been valuable for validating the near-field simulations of unsteady flow near the slat region and has been used by researchers at NASA as well as elsewhere. To allow unsteady pressure measurements on the surface of the slat, NASA fabricated a new slat model instrumented with dynamic pressure transducers. Because of acoustic reflections within a closed wall wind tunnel, IT was expected that the goal of benchmark quality acoustic measurements will only be met within an open jet facility. Because the aerodynamic loading in such a facility may be rather different from that in flight, there are open questions concerning the utility of the aeroacoustic measurements in an open jet facility. To help answer those questions, task order NNL11AD26T (boeing contract NNL10AA05B) was initiated to perform both aerodynamic and acoustic measurements on the 30P30N model at small angles of attack that are relevant to aircraft approach for landing. This task order builds upon NNL11AD26T and is intended to obtain several extra measurements of the 30P30N slat (in the same facility) that are still required to enable the goal of validated physics based predictions of slat noise. Based on measurements presented during the mid-term review o