Accession Number:

AD0672026

Title:

SOME MEASUREMENTS IN THE SELF PRESERVING JET,

Descriptive Note:

Corporate Author:

BOEING SCIENTIFIC RESEARCH LABS SEATTLE WASH FLIGHT SCIENCES LAB

Personal Author(s):

• Wygnanski,I.
• Fiedler,H.

Report Date:

1968-04-01

Pagination or Media Count:

63.0

Abstract:

The axisymmetric turbulent incompressible and isothermal jet was investigated by use of linearized constant temperature hot wire anemometers. It was established that the jet was truly self preserving some 70 diameters downstream of the nozzle and most of the measurements were made in excess of this distance. The quantities measured include mean velocity, turbulence stresses, intermittency, skewness and flatness factors, correlations, scales, low frequency spectra and convection velocity. The r.m.s. values of the various velocity fluctuations differ from those measured previously as a result of lack of self preservation and insufficient frequency range in the instrumentation of the previous investigations. It appears that Taylors hypothesis is not applicable to this flow, but the use of convection velocity of the appropriate scale for the transformation from temporal to spatial quantities appears appropriate. The energy balance was calculated from the various measured quantities and the result is quite different from the recent measurements of Sami 1967 which were obtained twenty diameters downstream from the nozzle. In light of these measurements some previous hypotheses about the turbulent structure and the transport phenomena are discussed. Some of the quantities were obtained by two or more different methods and their relative merits and accuracy are assessed. Author

Descriptors:

• *NOZZLE GAS FLOW
• *AXISYMMETRIC FLOW
• TURBULENCE
• MEASUREMENT
• REYNOLDS NUMBER
• SHEAR STRESSES
• ENERGY
• INCOMPRESSIBLE FLOW
• ANEMOMETERS
• VELOCITY
• SCALE
• TRANSPORT PROPERTIES

Subject Categories:

• Aerodynamics
• Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE