Multisource statistically optimized near-field acoustical holography.

Military jet noise source imaging using multisource statistically optimized near-field acoustical holography.

The identification of acoustic sources is critical to targeted noise reduction efforts for jets on high-performance tactical aircraft. This paper describes the imaging of acoustic sources from a tactical jet using near-field acoustical holography techniques. The measurement consists of a series of scans over the hologram with a dense microphone array. Partial field decomposition methods are per...

Preliminary Investigation of Multilobe Fighter Jet Noise Sources Using Acoustical Holography

An understanding of jet noise source mechanisms can facilitate targeted noise reduction efforts. This understanding has been enhanced with acoustic imaging technologies, such as near-field acoustical holography (NAH). In this study, multisource statistically optimized NAH (M-SONAH) was used to image the sound field near a tethered F-35 aircraft at multiple frequencies. A linear microphone array...

Session 1pSPa: Nearfield Acoustical Holography (NAH) Measurements and Applications 1pSPa4. Modified statistically optimized near-field acoustical holography for jet noise characterization

Near-field acoustical holography has been shown to be a useful tool for visualizing jet noise fields. It has been applied to a full-scale jet on an installed military aircraft with promising results, but the source characteristics in the extreme near field have been difficult to characterize because of the interference of acoustic reflections off the rigid reflecting plane beneath the jet. To p...

Source Visualization by Using Statistically Optimized Near-Field Acoustical Holography in Conical Coordinates

A comparison of statistically optimized near field acoustic holography using single layer pressure-velocity measurements and using double layer pressure measurements.

Statistically optimized near field acoustic holography (SONAH) is usually based on the assumption that all sources are on one side of the measurement plane whereas the other side is source free. An extension of the SONAH procedure based on measurement with an array of pressure-velocity probes has recently been suggested. An alternative method uses a double layer array of pressure transducers. B...