Naval Air Systems Command (NAVAIR) Program Management Activity 265 has developed full scale noise reducing chevrons in efforts to reduce the noise produced by General Electric F414 engines in the F/A 18E/F and EA-18G aircraft. BRRC provided oversight and measurement of NAVAIR’s demonstration and validation tests of these F/A-18E jet nozzle chevrons at Naval Air Engineering Station Lakehurst Jet Blast Deflector facility. BRRC measured noise for single-engine and multi-engine static operations and performed a comparative analysis of the chevron effectiveness. Image Credit: US Navy
Near-field Acoustic Holography, OH
BRRC, in partnership with BYU, developed innovative measurement and analysis methods using Near-field Acoustic Holography (NAH) to provide high-quality acoustic data and characterization of the jet-noise source region. The design includes a 150-channel NAH measurement array and data acquisition system, and a state-of-the-art holography processing capability. The prototype system was deployed to perform jet source-noise measurements from an F-22 at Holloman AFB in New Mexico. The culmination of this effort resulted in the ability to show how the scan-based measurements along one plane can be processed using NAH to produce a three-dimensional holographic representation of the sound radiation. This is the first time such a map has been obtained for a full-scale military jet aircraft. Learn more...
Large Weapon Environmental Noise Characterization, IL
BRRC assisted the U.S. Army in developing new measurement procedures for characterizing the environmental noise emitted by large weapon systems. The noise software tools, BNoise and RMTK Noise Tool, that DoD uses to predict and assess impacts of large weapon noise require accurate acoustic source emission models. These models require measurements of pressure waveform, peak level, and 1/3-octave-band sound exposure levels. A free-field representation of the sound source acoustical emission, containing no waveform signal perturbations due to the ground, other reflecting surfaces, or propagation anomalies, is required. This research is needed to ensure installation commanders have the best noise information possible to accomplish training and testing with minimum impact on the civilian communities surrounding installations. Image Credit: CERL