Accession Number : AD0436672

Title :   STATISTICAL PROPERTIES OF THE TURBULENT VELOCITY FLUCTUATIONS IN THE MIXING REGION OF A ROUND SUBSONIC JET,

Corporate Author : ADVISORY GROUP FOR AERONAUTICAL RESEARCH AND DEVELOPMENT PARIS (FRANCE)

Personal Author(s) : Davies, P. O. A . L. ; Fisher, M. J.

Report Date : APR 1963

Pagination or Media Count : 28

Abstract : The noise sources in a jet can be related to the turbulent velocity fluctuations in the mixing region. The structure and characteristics of the turbulence have been studied experimentally and the results are given in this report. It was found that the statistical characteristics of the turbulence can be expressed in terms of simple kinematic relationships as far as time averaged quantities are concerned. Measurements are presented which are expressed as probability distribution functions of the velocity about its mean value, or more simply as flatness and skewness factors. All the measurements taken together imply a fairly simple model of the turbulent structure which consists of flattened disc shape eddies of roughly equal axial and circumferential scale, with a radial scale of one-third the axial value. These are distributed randomly in the mixing region and have, in general, a different velocity from that of the mean flow. (Author)

Descriptors :   (*JET MIXING FLOW, TURBULENCE), GAS FLOW, SUBSONIC CHARACTERISTICS, MODEL TESTS, WIRE, ANEMOMETERS, VELOCITY, MEASUREMENT, CORRELATION TECHNIQUES, SHEAR STRESSES, STATISTICAL DISTRIBUTIONS, INTENSITY, STRUCTURES, JET ENGINE NOISE, WAKE, VORTICES, AERODYNAMIC CHARACTERISTICS, NOISE.

Distribution Statement : APPROVED FOR PUBLIC RELEASE