USA As Represented by Secretary of the Navy

Michael A Sartori

Joseph A Clark

Daniel F Dozier

Moon H Cho

Acoustic near field measurement apparatus uniquely featuring mechanical eomy, in terms of placement and motion of one or more acoustic measurement devices, which is accorded by the geometric character of a structure having indicia of symmetry. One or more devices are arranged, and/or caused to move with up to three degrees of freedom, so as to manifest conformance with respect to the surface of the structure. If desired, virtually complete acoustic near field mapping of the structure can be effectuated. Examples of the various embodiments of this invention include: circumferentially conformal arrayal of devices in combination with longitudinal movement of the arrayal; longitudinally conformal arrayal of devices in combination with circumferential movement of the arrayal; movement of one or more devices in a path or paths which are circumferentially conformal; movement of one or more devices in a path or paths which are longitudinally conformal; movement of one or more devices in a path or paths which are radial. For some embodiments a single device can be caused to move circumferentially, longitudinally and radially, and thus is provided three degrees of freedom. The apparatus according to this invention is more feasible and reliable than previous apparatus, especially for larger structures.

Apparatus for acoustic near field scanning using conformal arrayal

Acoustic near field measurement method uniquely featuring mechanical econ, in terms of placement and motion of one or more acoustic measurement devices, which is accorded by the geometric character of a structure having indicia of symmetry. One or more devices are arranged, and/or caused to move with up to three degrees of freedom, so as to manifest conformance with respect to the surface of the structure. If desired, virtually complete acoustic near field mapping of the structure can be effectuated. Examples of the various embodiments of this invention include: circumferentially conformal arrayal of devices in combination with longitudinal movement of the arrayal; longitudinally conformal arrayal of devices in combination with circumferential movement of the arrayal; movement of one or more devices in a path or paths which are circumferentially conformal; movement of one or more devices in a path or paths which are longitudinally conformal; movement of one or more devices in a path or paths which are radial. For some embodiments a single device can be caused to move circumferentially, longitudinally and radially, and thus is provided three degrees of freedom. The method according to this invention is more feasible and reliable than previous methods, especially for larger structures.

Method for acoustic near field scanning using conformal arrayal

A system and method are provided to reduce a structure's far field acoustic adiation signature. A plurality of acoustic sensors are positioned in the acoustic near field of the structure for measuring the near field acoustic radiation of the structure. A programmable controller generates a prediction of the structure's far field acoustic radiation signature using the near field acoustic radiation. The prediction is then used to generate a noise control signal applied to a plurality of acoustic radiators suspended within the structure. The radiators convert substantially all of the noise control signal to airborne acoustic energy within the structure.

Far field acoustic radiation reduction

A method and system for mapping the acoustic near field of a stationary al symmetric structure are provided. The structure is subjected to a rotating excitation energy profile from a plurality of stationary excitation sites located radially around the structure. The acoustic near field of the structure due to the rotating excitation energy profile is measured along at least one line that conforms to a longitudinal surface of the structure. Mapping of the acoustic near field is complete when one rotation of the rotating excitation energy profile is complete.

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McLean, VA, United States of America

Michael A Sartori