- Author
-
Pitts, W. M.
- Title
- Effects of Global Density and Reynolds Number Variations on Mixing in Turbulent, Axisymmetric Jets.
- Coporate
- National Bureau of Standards, Gaithersburg, MD
- Sponsor
- Air Force Office of Scientific Research, Washington, DC
- Report
-
NBSIR 86-3340,
March 1986,
172 p.
- Distribution
- Available from National Technical Information Service
- Contract
- AFOSR-ISSA-00012
- Keywords
-
concentration fluctuations
|
concentration measurement
|
density effects
|
flow visualization
|
rayleigh light scattering
|
reynolds number
|
turbulent flow
|
axisymmetric jets
- Abstract
- Shadowgraphy and laser-induced Rayleigh light scattering measurements of centerline concentration have been utilized to investigate the effects of global density and Reynolds number variations on the mixing behavior of a turbulent, axisymmetric jet. Density variations are introduced by using different gases for the jet and the surrounding coflow. Values of the jet/coflow density ratio have been varied from 0.14 to 37. The shadowgraph measurements give a qualitative indication of the variations in average mixing behavior and turbulent structure which occur when the jet/coflow density ratio and the Re are varied. These trends are quantified by the Rayleigh scattering concentration measurements which give measurements of average centerline concentration as well as the second through fourth moments of the concentration fluctuations. Extensive comparisons of experimental results are made with previous literature findings. Integral analysis has been employed to provide a framework for analysis of the data. The results of this study have led to the proposal of a simple, qualitative theory based on two reasonable assumptions concerning the flow behavior which gives predictions which are in agreement with the experimental findings.