Abstract
We present exploratory tests of a new optical method which measures directly two components of the 3-D power spectrum of the refractive-index fluctuation. The method was applied to a Mach 2 turbulent shear layer. Length scales of 0.1 mm to 1.0 mm were resolved within a shear-layer thickness ranging from 5 mm to 10 mm. At low-to-moderate wavenumbers, the spectral behavior is roughlyκ −3, while at higher wavenumbers it isκ −3.7. These spectral slopes are in agreement with prevailing theoretical predictions for anisotropic (low-wavenumber) and isotropic (high-wavenumber) turbulence.
Similar content being viewed by others
Abbreviations
- a :
-
speed of sound
- l :
-
eddy size
- n :
-
refractive index
- S :
-
mean strain rate
- S h :
-
mean shear
- T :
-
static temperature
- U :
-
freestream velocity
- x :
-
axial direction
- y :
-
transverse direction
- z :
-
spanwise direction
- δ :
-
shear-layer thickness
- δ′:
-
=dδ/dx: growth rate
- ɛ :
-
viscous dissipation
- ΔU :
-
=U 1−U 2
- κ :
-
wavenumber
- ϱ :
-
density
- Φ :
-
3-D power spectrum
- 1:
-
fast stream
- 2:
-
slow stream
References
Albrecht GF;Robey HE;Moore TR (1990) Optical technique for the measurement of turbulent spectra using the photorefractive properties of BaTiO3. Appl Phys Lett 57: 864–866
Brigham EO (1974) The Fast Fourier Transform. New Jersey: Prentice Hall
Clifford SF (1978) The Classical Theory of Wave Propagation a Turbulent Medium. Topics in Appl Phys 25: 26–43
Elliott GS;Samimy M (1990) Compressibility effects in free shear layers. Phys Fluids A 29: 1231–1240
Robey HF (1990) Spectrum of a passive scalar in the inertial-convective subrange of an anisotropic turbulent flow. Phys Rev Lett 65: 1360–1361
Robey HF; Albrecht GF; Moore TR (1990) An optical technique for direct measurement of 2-D spectral density of a passive scalar in a turbulent flow. AIAA-90-1667
Papamoschou D;Roshko A (1988) The compressible turbulent shear layer: an experimental study. J Fluid Mech 197: 453–477
Papamoschou D; Robey HF; Lin M; Bunyajitradulya A (1993) Non-intrusive technique for measurement of power spectra in compressible turbulence. AIAA-93-0633
Tennekes H;Lumley JL (1972) A First Course in Turbulence. Cambridge: MIT Press
Author information
Authors and Affiliations
Additional information
]This study was funded by a grant from Lawrence Livermore National Laboratory and by a grant from the California Space Institute. DP is indebted to HFR and Dr. Alfred C. Buckingham of LLNL for their support.
Rights and permissions
About this article
Cite this article
Papamoschou, D., Robey, H.F. Optical technique for direct measurement of power spectra in compressible turbulence. Experiments in Fluids 17, 10–15 (1994). https://doi.org/10.1007/BF02412798
Issue Date:
DOI: https://doi.org/10.1007/BF02412798