USA As Represented by Secretary of the Navy

William L Keith

Kimberly M Cipolla

Alia W Foley

Michael R Williams

Heather L Chamblee

Jeff Dusek

An assembly is provided for determining a parametric design of a large eddy breakup device in which the assembly comprises a water tunnel turbulent pipe flow section; a large eddy breakup device ring disposed within the pipe flow section; and a wall pressure sensor array operable to detect wall pressure in the turbulent pipe flow section. Energy in a wavenumber frequency spectra of wall pressure fluctuations is redistributed via changes to the parametric design in order to minimize turbulent wall pressure fluctuations with the result of reduced flow noise and drag.

Apparatus for turbulent boundary layer control and flow noise reduction

An acoustic array hose is provided for towing behind a marine vessel. The acoustic array includes acoustic sensors, a hydraulic fill-fluid circumferentially surrounding the acoustic sensors, and an array hose wall of polyurethane with single wall carbon nanotubes embedded therein. The hose wall circumferentially surrounds the hydraulic fill fluid along a length of the array hose. When an electrical current is applied to the towed array, the nanotubes align with the hose wall with the effect of strengthening the hose wall of the towed array.

Carbon nanotube polymer composite hose wall

A system is provided that employs a programmable computer on which a graphical user interface provides parametric design and analysis of pressure sensor arrays used in aero- or hydroacoustic investigations. Use of the system allows for scientific and parametric investigations of turbulent boundary layer physics, as well as iterative array design optimization. Additionally, the system including the graphical user interface facilitates comparison of the results of current models for wall pressure with past theoretical or experimental wall pressure.

Graphical user interface for flow noise modeling, analysis, and array design

An apparatus is provided to directly measure the flow noise characteristics of both acoustic sensors and accelerometers mounted in a towed array hose. Sensors can be mounted in a full-scale diameter array module test apparatus and can be subjected to high Reynolds number flow fields that have the physical features of at-sea towing conditions. Additionally, rapid re-design of sensor mountings, hose materials, and actual sensors can be accomplished and evaluated. The parameters of internal tension and flow speed can vary independently in order to determine their importance.

Towed array flow noise test apparatus

A method for reducing noise in a towed acoustic array includes providing a towed array having a length, diameter, frequency range and tow speed. The relationship between tension in the towed array and wall pressure fluctuation spectral levels is determined. Wall pressure fluctuation spectral levels are related to the noise in the array. An optimal towed array tension is calculated using the determined relationship. Tension is increased to the optimal towed array tension by either provided additional towed array hose or a drogue at the end of the towed array.

Method for reducing flow induced vibration and noise in towed arrays

A towed array is provided with hot-film sensors and anemometer circuitry to calculate the angle of inclination of the towed array in real time during deployment of the towed array in a sea water environment. The hot-film sensors are arranged in pairs along the length of the towed array to increase the sensitivity of the inclination angle determinations and are located flush with an exterior surface of the towed array to minimize interference with the operation of the towed array. The pairs of hot-film sensors determine the local shear stresses on the towed array, and these measurements are converted to inclination angles using an empirically derived look-up table.

Method to estimate towed array angles

A towed array is provided with hot-film sensors and anemometer circuitry to calculate the angle of inclination of the towed array in real time during deployment of the towed array in a sea water environment. The hot-film sensors are arranged in pairs along the length of the towed array to increase the sensitivity of the inclination angle determinations and are located flush with an exterior surface of the towed array to minimize interference with the operation of the towed array. The pairs of hot-film sensors determine the local sheer stresses on the towed array, and these measurements are converted to inclination angles using an empirically derived look-up table.

Device for estimating local towed array angles

A system and method are provided for detecting an acoustic signal in the presence of flow noise produced by the turbulent flow field that develops about a hosewall of a towed array. Pressure is sensed with pressure sensors at two diametrically-opposed locations at the surface of the hosewall over a period of time. The sensed pressure signals are used to generate an ensemble-averaged cross-spectra which effectively cancels out the flow noise while retaining the acoustic signal associated with a possible target of interest.

System and method for detecting an acoustic signal in the presence of flow noise

A method is presented for determining inner and outer boundary layer length scales from a succession of drag measurements of a cylindrical body in order to estimate flow noise and for computational modeling of the dynamics of towed arrays in a fluid medium. A succession of measurements of the total drag on a cylinder under tow at uniform known conditions (flow speed, fluid density, fluid viscosity, cylindrical body geometry) is taken. After each measurement, the cylinder is truncated by a fixed amount, and the process is repeated for the length of the cylinder. The measurements provide a spatially and temporally averaged measure of the mean wall shear stress and momentum thickness, from which the inner and outer length scales can be determined. The inner and outer boundary layer length scales may then be used for estimation of flow noise on towed cylindrical bodies and arrays.

Method for determining local inner and outer boundary layer length scales from drag measurements in high Reynolds number turbulent flows

A method and apparatus are presented for determining turbulent boundary layer thickness. In this method and apparatus, a pair of sensors are mounted to a solid surface interfacing with a fluid at two separate stream wise locations. A voltage output from the pair of sensors is recorded and a real non-dimensional value of a correlation coefficient is computed with measured data from the recorded voltage. A laboratory non-dimensional value of the correlation coefficient is independently determined from laboratory data. The real non-dimensional value is compared with the laboratory non-dimensional value to obtain a boundary layer thickness having a value which minimizes a difference between the values of the real non-dimensional value and the laboratory non-dimensional value.

Turbulent boundary layer thickness estimation method and apparatus

A heat exchange tube includes a tubular conduit for flowing a working fluid therethrough and for conducting heat between the working fluid and a thermal field proximate the tube, and a wire extending axially through the tubular conduit and spaced from an inside surface of the tubular conduit. The invention also provides a method for increasing heat transfer about a tubular conduit by positioning a wire in the conduit.

Vorticity generator for improving heat exchanger efficiency

A unique combination of two transducers. A hot film shear stress gauge and a piezoelectric pressure transducer are coaxially located along the longitudinal centerline of a cylindrical metal shell. The hot film shear stress gauge is exposed to the fluid while the pressure transducer is positioned directly below. Conductors are attached to each and the remaining volume filled with plastic to form a colinear unit. The conductors attached to the hot film element provide power while the conductors attached to the piezoelectric transducer transmit pressure produced electrical signals therefrom. The resulting configuration allows the measurement of fluctuating shear stress and fluctuating pressure to be made simultaneously at a single spatial location at a solid wall bounding a turbulent fluid flow layer.

Growing community of inventors

Ashaway, RI, United States of America

William L Keith