Accession Number : AD0754260

Title :   Flow and Acoustic Measurements on a Convergent Nozzle Supersonic Jet Ejector,

Corporate Author : GENERAL ELECTRIC CO SCHENECTADY N Y RESEARCH AND DEVELOPMENT CENTER

Personal Author(s) : Nagamatsu,H. T. ; Pettit,W. T. ; Sheer,R. E. , Jr

Report Date : APR 1969

Pagination or Media Count : 43

Abstract : A conical convergent nozzle with a throat diameter of 2 inches was used to give a Mach number 1.5 room temperature primary jet with which various combinations of rods, shroud and induced flow were investigated as noise suppresors. Small shock wave disturbances were found to be extremely effective in reducing the supersonic region of the jet and accelerating the mixing between the primary and secondary jets within the shroud. These effects can result in as much as 17 db acoustic power level reduction. From aerodynamic measurements at the shroud exit, the amount of sound power reduction, calculated on the basis of the unbounded mixing with the ambient of the reduced velocity mixed primary and secondary jets, was far from achieved due to noise sources within the shroud. These sources caused by shock waves and the internal primary and secondary jet mixing can increase the free stream turbulence level of the mixed jets. The acoustic power level spectra of the ejector noise shows it to be broadband. (Author)

Descriptors :   (*JET ENGINE NOISE, REDUCTION), (*CONICAL NOZZLES, NOZZLE GAS FLOW), SUPERSONIC FLOW, ACOUSTIC PROPERTIES, SHOCK WAVES, CAPTIVE TESTS

Subject Categories : Acoustics
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE