Non-invasive acoustic velocimetric apparatus and method
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorWilliam L. Konrad
Life of this patent
Estimating the term…
Abstract
A first projector that generates a beam of acoustic energy having a first equency, and a second acoustic projector that generates a beam of acoustic energy having a second frequency are provided. Interaction between the intersecting beams and particles present in the aquatic environment cause radiation of a third frequency at the region of beam intersection. The third frequency acoustic waves returned from the non-linear acoustic radiating area are monitored at a hydrophone, and the travel time of sound from the projectors to the hydrophone is determined. Successive readings can be made at various depths to obtain a velocity profile. Velocimetry can thus be accomplished free from any need to lower a tethered physical velocimeter into the depths.
Claims9
An apparatus for determining the acoustic velocity in a fluid at depth comprising:
- a first acoustic projector submerged in said fluid to project a first narrow acoustic beam having a first preselected frequency through said fluid;
- a second acoustic projector submerged in said fluid to project a second narrow acoustic beam having a second preselected frequency through said fluid, said second acoustic beam intersecting said first acoustic beam, said first and second beams producing a non-linear intermodulation product frequency by interaction with particles disposed in said fluid;
- a hydrophone submerged in said fluid for receiving sounds from said fluid;
- a filter joined to said hydrophone for filtering said sounds received by said hydrophone to receive a sound having a preselected frequency;
- and
- a controller joined to said filter to detect said preselected frequency.
A method for calculating the velocity of sound in a fluid comprising the steps of:
- emitting a first acoustic beam having a first preselected frequency into said fluid;
- emitting a second acoustic beam having a second preselected frequency into said fluid, said second beam intersecting said first beam;
- receiving an intermodulation product at a hydrophone disposed in said fluid, said intermodulation product being generated by the interaction of said first beam and said second beam at the region of intersection with particles disposed in said fluid;
- measuring the return time of said intermodulation product produced by said intersection of said beams;
- and
- calculating the velocity of sound between said intersection of said beams and said hydrophone from said measured return time.
Dependencies are inferred from the claim text.