Anthony A. Ruffa

Acoustic wave propagation through periodic bubbly liquids

A three‐dimensional finite‐element analysis is used to determine the acoustic behavior of plane waves propagating through bubbly liquids having periodic bubble distributions. The results obtained from the model include the effective phase speed and attenuation of the medium, the acoustic field in the region of each bubble, and the virtual mass for both the monopole and dipole modes of bubble oscillation. The results are in agreement with both experimental data and previous analytical results.

Acoustical cavitation suppressor for flow fields

A cavitation suppressor using acoustic energy to suppress flow field cavitation is provided. The suppressor system has a plurality of pressure transducers located along the outer surface of a sonar dome. These transducers are powered through a controller which receives flow data, that is, pressure fluctuations in the flow field and in response operates acoustic arrays located aft of the pressure transducers. The controller provides a sonic impulse having frequency and pulse duration selectant to reduce cavitation in the flow field around the sonar dome.

Modification to towed array bulkheads

A towed array of hydrophone modules employs bladders that are mounted to the bulkheads at the ends of the hose sections. The bladders are configured and pressurized so that pressure waves produced by the oscillatory motion of the bulkhead are suppressed by the bladders thereby significantly diminishing noise due to the breathing waves.

Miniature low frequency acoustic transmitter

A miniature lightweight transmitter that mechanically generates low-frequency acoustic energy is described, wherein one or more miniature balloons filled with air are positioned at the center of a pressure vessel filled with water and tethered in place. The system is then driven into resonance by using transducers that directly drive the wall of the pressure vessel or by using a piston to drive fluid into and out of the pressure vessel.

Acoustic processing for estimating size of small targets

Abstract : A method is provided for estimating the size of an object from a region of a fluid medium when that object is emitting acoustic radiation of-known wavelength lambda on its own or as the result of being interrogated by acoustic pulses that reflect from the object. The acoustic radiation is monitored using a line array of N acoustic receivers such that N signals indicative of the acoustic radiation are generated. M time series summations are formed using the N signals. Each of the M time series summations is formed using a unique time delay predicated on a corresponding unique estimated speed of propagation of the acoustic radiation where M estimated speeds of propagation are defined. For an object in the region having a diameter D on the order of lambda, the M values will vary as a function of the M estimated speeds of propagation with the resulting distribution of the M values being indicative of diameter D.