An experimental investigation of compressible, turbulent mixing layers
Goebel, Steven George
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https://hdl.handle.net/2142/22200
Description
Title
An experimental investigation of compressible, turbulent mixing layers
Author(s)
Goebel, Steven George
Issue Date
1990
Doctoral Committee Chair(s)
Dutton, J. Craig
Department of Study
Mechanical Science and Engineering
Discipline
Mechanical Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Aerospace
Engineering, Mechanical
Language
eng
Abstract
An investigation of compressible, turbulent mixing layers has been completed. The experiments were conducted using pressure measurements, schlieren photography and velocity measurements with a two-component laser Doppler velocimeter system. These diagnostic systems were developed for use with the mixing layer wind-tunnel facility. Many conditions were evaluated, and seven mixing layer cases were fully examined, with relative Mach numbers ranging from 0.40 to 1.97, which spans the region of significant compressibility effects. The spatial development and similarity of the mixing layers were examined, as well as the entrainment process and the effects of particle dynamics. Analyses to predict the mean density profiles, mean transverse velocity profiles, shape of the kinematic Reynolds stress profiles and entrainment mass fraction of a fully developed, compressible mixing layer were also developed.
From the schlieren photographs, no organized, large-scale structures were observed to dominate the mixing layers under the conditions of this study. The development of the mixing layers required a Reynolds number (based on the freestream velocity difference and local mixing layer thickness) on the order of 1 $\cdot$ 10$\sp5$. In the fully developed regions of the mixing layers, it was found that transverse turbulence intensities and normalized kinematic Reynolds stresses decreased with increasing relative Mach number like the decreases measured in normalized growth rate, while the streamwise turbulence intensities and kinematic Reynolds stress correlation coefficients remained approximately constant. By examining the LDV velocity measurements from particles with different response characteristics, it was shown that particle dynamics effects were not a problem with these measurements. Also, by measuring velocity profiles on both sides of the wind-tunnel midplane, it was found that the flow fields were reasonably two-dimensional.
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