Accession Number : ADA257114


Title :   Determination of Turbulent Velocities by Nonlinear Acoustic Scattering


Descriptive Note : Final rept. 1991-1992


Corporate Author : NAVAL ACADEMY ANNAPOLIS MD


Personal Author(s) : Parker, 111, James E


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a257114.pdf


Report Date : 08 May 1992


Pagination or Media Count : 150


Abstract : The scattering of sound by the nonlinear interaction of two sound beams in the presence of turbulence is used to experimentally measure the turbulent velocities generated by a submerged water jet. When two sound beams of primary frequencies f01 and f02 intersect in a region of turbulent flow, the nonlinear scattering generates sum and difference frequency components (f0+ = f01 f02 and f0- = f01 - f02) which radiate outside the interaction region. In the absence of turbulence, the crossed beams do not produce radiated sum and difference frequencies. In this experiment, two transducers emit continuous wave focused sound beams of frequencies f01 = 2.0 MHz and f02 = 2.1 MHz, respectively. A receiving transducer, located outside the interaction region, detects the scattered sum frequency (f0 = 4.1 MHz.) Scattering results measured at 80 degree angles for each of 11 scan positions across the jet are used to map out the velocity correlation coefficients of the turbulence. Results are then compared with earlier published experiments that use conventional hotwire probes to measure a similar turbulent jet flow in air. nonlinear acoustics; sound- scattering; sound-waves; ultrasonic-waves.


Descriptors :   *VELOCITY , *TURBULENT FLOW , *ACOUSTIC SCATTERING , *UNDERWATER ACOUSTICS , FREQUENCY , ANGLES , PROBES , SCATTERING , INTERACTIONS , CORRELATION , COEFFICIENTS , WATER JETS , HOT WIRE , JET FLOW , SOUND WAVES , FLOW , TRANSDUCERS , ACOUSTICS , MAPS , SOUND , DIFFERENCE FREQUENCY , ULTRASONICS , REGIONS , AIR , WATER , WIRE , CONTINUOUS WAVES , TURBULENCE


Subject Categories : Acoustics
      Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE