Accession Number : ADA257887


Title :   A General Introduction to Aeroacoustics and Atmospheric Sound


Descriptive Note : Contractor rept.


Corporate Author : INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA


Personal Author(s) : Lighthill, James


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a257887.pdf


Report Date : Oct 1992


Pagination or Media Count : 35


Abstract : This paper uses a single unifying principle (based upon the nonlinear momentum-flux effects produced when different components of a motion transport different components of its momentum) to give a broad scientific background to several aspects of the interaction between airflows and atmospheric sound. First, it treats the generation of sound by airflows of many different types. These include, for example, jet-like flows involving convected turbulent motions -- with the resulting aeroacoustic radiation sensitively dependent on the Mach number of convection -and they include, as an extreme case, the supersonic boom (shock waves generated by a supersonically convected flow pattern). Next, the paper analyses sound propagation through nonuniformly moving airflows, and quantifies the exchange of energy between flow and sound; while, finally, it turns to problems of how sound waves on their own may generate the airflows known as acoustic streaming. aeroacoustics; turbulence; sonic boom.


Descriptors :   *ACOUSTIC WAVES , *AIR FLOW , *SUPERSONIC FLOW , PROPAGATION , RADIATION , MOTION , TURBULENCE , TRANSPORT , ACOUSTICS , ACOUSTIC ATTENUATION , SONIC BOOM , CONVECTION(ATMOSPHERIC) , DOPPLER EFFECT , MOMENTUM , SOUND WAVES , MACH NUMBER , SOUND , WAVE PROPAGATION , CONVECTION , ENERGY , SHOCK WAVES , INTERACTIONS


Subject Categories : Acoustics
      Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE