Accession Number : ADD017339

Title :   Method and System for Suppressing Noise Induced in a Fluid Medium by a Body Moving Therethrough.

Descriptive Note : Patent, Filed 2 Sep 93, patented 25 Oct 94,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Katz, Richard A

Report Date : 25 Oct 1994

Pagination or Media Count : 18

Abstract : A method of detecting the onset of turbulence in connection with a body moving through a fluid medium and reducing turbulence noise acoustic sensor systems carried thereby. First, the body is supplied with sensors each for generating a signal suitable for measuring amplitude of pressure fluctuations of the medium proximate a region of said sidewall of the body in at least a region of the body in which turbulence is expected to occur. During a reference stage during which the body moves through the fluid medium when it is known that turbulence is occuring around at least a portion of said body the sensors each generate reference temporal pressure data representing fluctuations in pressure of the fluid medium around said body. In response to reference temporal pressure data representing by sensors in a turbulence zone at which turbulence is occurring and sensors in a transition zone at which turbulence zone and a laminar flow zone, method-of-delay phase portraits are generated for a progression selected delay intervals. During an operational stage, the signals from the sensors are filtered to generate a portion representing the turbulence due to motion of the body through a portion representing signals from external acoustic signal sources, and the turbulence signal portion is used to generate signals of appropriate phase which are injected into the medium to reduce the turbulence noise signals. (AN)

Descriptors :   *TURBULENCE, *FLOW NOISE, *PATENTS, PRESSURE GRADIENTS, SIGNAL PROCESSING, DATA PROCESSING, ACOUSTIC DETECTION, DELAY, ACOUSTIC SIGNALS, NOISE REDUCTION, ACOUSTIC FILTERS, SOUND WAVES, BOUNDARY LAYER TRANSITION, AMPLITUDE, LAMINAR FLOW, SOUND PRESSURE, BOUNDARY LAYER FLOW, VARIABLE PRESSURE, SOUND GENERATORS

Subject Categories : Acoustics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE