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Laser Diagnostic Development and Measurement and Modeling of Turbulent Flowfields of Jets and Wakes. Part 3. The Development of a Two-Channel CW Time-Resolved Laser Raman Spectroscopy (TiLaRS) System for Measurements in Gas Flowfields.

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Final rept. 1 Apr 78-30 Sep 82,

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The design and performance of a photon counting, two-channel spectroscopic system using the 6-W, 448-nm line of a cw argon ion laser is described. The two channels are formed by use of cylindrical optics and special slit mirrors set up following the exit slit of a conventional double spectrometer. The system is capable of dynamic, simultaneous measurements of either the concentrations of two gas species in cold flow or the temperature and concentration of a single gas species, such as N2, in a flame. Measurements are accomplished by recording the intensities of two spontaneous rotational Raman lines with spectral bandwidths between 0.04 and 0.08 nm. Up to 4096 samples or reads from each of the two channels can be recorded by a dedicated minicomputer at rates up to 10 kHz. Studies of a CH4 diffusion flame at sampling rates of 20 to 100 Hz and a room-temperature, axisymmetric C02 jet at rates up to 2.0 kHz were carried out. Analysis of the data from these studies include mean and rms profiles, probability density functions pdfs, power spectral density functions, autocorrelation functions, cross correlation functions, and determinations of skewness and kurtosis in the pdfs and the C02 fluctuations.

Subject Categories:

  • Lasers and Masers
  • Test Facilities, Equipment and Methods
  • Optical Detection and Detectors
  • Fluid Mechanics
  • Combustion and Ignition

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