Measurements of passive-scalar spectra for grid turbulence using a nonlinear optical technique

Conference · Tue Jan 01 00:00:00 EST 1991

OSTI ID:5999980

O'Hern, T J; Torczynski, J R; Neal, D R; Shagam, R N ^[1]; Robey, H F ^[2]

---

1. Sandia National Labs., Albuquerque, NM (USA)
2. Lawrence Livermore National Lab., CA (USA)

A nonlinear optical technique has been applied to grid turbulence measurements. A laser beam passing through a turbulent region acquires phase perturbations related to the density perturbations it encounters. If the laser beam is then passed through a crystal of barium titanate (BaTiO{sub 3}), a photorefractive nonlinear optical material, the small-amplitude perturbations to the beam are passed but the large-amplitude unperturbed portion of the beam is deflected away from the beam path. An optical Fourier transform of the perturbations performed by a lens yields the two-dimensional density-perturbation (passive-scalar) spectrum at the lens focal plane or, alternatively, a photorefractive schlieren photograph at the lens image plane. As a test application for this technique, a system was assembled to study the downstream evolution of the density-perturbation spectrum in grid turbulence produced by an electrically heated screen spanning the test section of a wind tunnel. Near the screen, the spectrum is found to consist primarily of large-amplitude peaks at the fundamental and the first few harmonics of the screen-wake spatial frequency. As expected, these amplitudes are observed to decay rapidly in the downstream direction. 8 refs., 12 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5999980
• Report Number(s): SAND-90-2541C; CONF-910684-1; ON: DE91005310
• Resource Relation: Conference: 1. ASME/JSME fluids engineering conference, Portland, OR (USA), 23-26 Jun 1991
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
47 OTHER INSTRUMENTATION
TURBULENT FLOW
MEASURING METHODS
BARIUM COMPOUNDS
CRYSTALS
FOURIER TRANSFORMATION
LASER RADIATION
NONLINEAR OPTICS
OPTICAL SYSTEMS
SPECTRAL DENSITY
TITANIUM OXIDES
WAVE PROPAGATION
WIND TUNNELS
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
ELECTROMAGNETIC RADIATION
FLUID FLOW
FUNCTIONS
INTEGRAL TRANSFORMATIONS
OPTICS
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
SPECTRAL FUNCTIONS
TITANIUM COMPOUNDS
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
TUNNELS
UNDERGROUND FACILITIES
640410* - Fluid Physics- General Fluid Dynamics
440600 - Optical Instrumentation- (1990-)