Accession Number : ADA094293


Title :   High Velocity Jet Noise Source Location and Reduction. Task 3 - Experimental Investigation of Suppression Principles. Volume I. Suppressor Concepts Optimization


Descriptive Note : Final rept. Oct 1974-Oct 1977


Corporate Author : FEDERAL AVIATION ADMINISTRATION WASHINGTON DC SYSTEMS RESEARCH AND DEVELOPMENT SERVICE


Personal Author(s) : Brown, R H ; Clapper, W S ; Joy, W ; Smith, M A ; Stringas, E J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a094293.pdf


Report Date : Dec 1978


Pagination or Media Count : 370


Abstract : Experimental investigations of suppression principles were conducted including developing an experimental data base, developing a better understanding of jet noise suppression principles, and formulating empirical methods for the acoustic design of jet noise suppressors. Acoustic scaling has been experimentally demonstrated, and five 'optimum' nozzles have been selected for subsequent anechoic free-jet testing. This report is organized into four volumes under separate cover: Volume I - Verification of Suppression Principles and Development of Suppression Prediction Methods, Volume II - Parametric Testing and Source Measurements, Volume III - Suppressor Concepts Optimization, and Volume IV - Laser Velocimeter Time-Dependent Cross Correlation Measurements. The experimental studies reported in Volume II involved acquisition of detailed far-field, acoustic data and of aerodynamic jet-flow-field data on several baseline and noise-abatement nozzles. These data were used to validate the theoretical jet noise prediction method of Task 2 and to develop and validate the empirical noise-prediction method presented herein. A series of seven suppressor configurations (ranging from geometrically simple to complex) were tested to establish the relative importance of four jet noise mechanisms (fluid shielding, convective amplification, turbulent mixing, and shock noise). In general, mechanical suppressors exhibit a significant reduction in shock noise relative to a baseline conical nozzle, reduce the effectiveness of fluid shielding (increase rather than suppress noise), reduce the effectiveness of convective amplification (reduce noise), and produce a modest reduction in turbulent mixing noise.


Descriptors :   *NOISE REDUCTION , *SUPPRESSORS , *JET ENGINE NOISE , DATA BASES , COMPUTERIZED SIMULATION , OPTIMIZATION , HIGH VELOCITY , THEORY , JET FLOW , CROSS CORRELATION , TURBOJET ENGINES , VARIABLE CYCLE ENGINES , CONICAL NOZZLES , EXHAUST NOZZLES , NOZZLE GAS FLOW , FLOW NOISE , TURBULENT FLOW , MATHEMATICAL PREDICTION , SHIELDING , PLUMES


Subject Categories : Acoustics
      Fluid Mechanics
      Jet and Gas Turbine Engines


Distribution Statement : APPROVED FOR PUBLIC RELEASE