Rotational CARS application to simultaneous and multiple-point temperature and concentration determination in a turbulent flow

Technical Report · Wed Feb 01 04:00:00 EST 1984

OSTI ID:6718494

Snow, J B; Murphy, D V; Chang, R K

Coherent Anti-stokes Raman Scattering (CARS) from the pure rotational Raman lines of N2 is employed to measure the instantaneous rotational temperature of N2 gas at room temperature and below with good spatial resolution. A broad-bandwidth dye laser is used to obtain the entire rotational spectrum from a signal laser pulse the CARS signal is then dispersed by a spectrograph and recorded on an optical multichannel analyzer. A best-fit temperature is found in several seconds with the aid of a computer for each experimental spectrum by a least squares comparison with calculated spectra. The model used to calculate the theoretical spectra incorporates the temperature and pressure dependence of the pressure-broadened rotational Raman lines, includes the nonresonant background susceptibility, and assumes that the pump laser has a finite linewidth. Temperatures are fit to experimental spectra recorded over the temperature range of 135 to 296K, and over the pressure range of 0.13 to 15.3 atm. In addition to the spatially resolved single point work, we have used multipoint CARS to obtain information from many spatially resolved volume elements along a cylindrical line (0.1 x 0.1 x 2.0 mm). We also obtained qualitative information on the instantaneous species concentration and temperature at 20 spatially resolved volume elements (0.1 x 0.1 x 0.1 mm) along a line.

• Research Organization: Yale Univ., New Haven, CT (USA)
• OSTI ID: 6718494
• Report Number(s): N-8419044; NASA-CR-3783
• Country of Publication: United States
• Language: English

Related Subjects

640410* -- Fluid Physics-- General Fluid Dynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DYE LASERS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUID FLOW
LASER SPECTROSCOPY
LASERS
LEAST SQUARE FIT
LIQUID LASERS
MAXIMUM-LIKELIHOOD FIT
NITROGEN
NONLINEAR OPTICS
NONMETALS
NUMERICAL SOLUTION
OPTICS
RAMAN SPECTROSCOPY
RESOLUTION
ROTATIONAL STATES
SPATIAL RESOLUTION
SPECTROSCOPY
TURBULENT FLOW