Development, validation and application of a newly developed rig facility for investigation of jet aeroacoustics

Over the last decades, significant improvements have been achieved in terms of noise reduction for jet engine aircraft. Nevertheless, jet noise remains one of the major sound sources from commercial aircraft, particularly during take-off. To develop strategies for jet noise reduction, it becomes paramount to understand the mechanisms of sound production and radiation from the experimental point of view. For this reason, researchers need high-quality noise data, obtained under proper conditions for both the acoustic and flow fields of scaled jets. This paper reports the development, validation and application of a new jet rig facility built at Federal University of Santa Catarina for investigations of jet noise. Issues relating to limited budget, deadline fulfillment and inner space restrictions, made the design and construction of the facility particularly difficult. Such drawbacks were overcome by designing carefully every system making up the whole facility, some of them based on CFD analyses, as well as by employing tailored solutions to some systems. Throughout the paper, the infrastructure of facility and its main systems are presented as well as major design requirements are discussed. Subsequently, the free-field qualification and the determination of acoustic far-field for the jet source, concerning the anechoic chamber, are described. With the aim of evaluating the acoustic performance of the facility, noise data were acquired for jet flows with Mach numbers from 0.3 to 0.9 and observer locations from 60 to 150 degrees. Additionally, hot-wire anemometry measurements were performed at different axial positions along the jet to illustrate the turbulent character of flows generated. Results of flow and noise measurements revealed an acoustically clean signature as well as turbulence properties in good agreement with data from other facilities. Finally, the paper outlines the underway research works at the mentioned facility and new directions for further work.