CARS investigations in sooting and turbulent flames. Technical report, 1 October 1977-28 February 1979

Technical Report · Thu Mar 01 04:00:00 EST 1979

OSTI ID:5709757

Eckbreth, A C

Coherent anti-Stoke Raman spectroscopy (CARS) investigations in sooting, laminar and turbulent, propane-fueled diffusion flames are reported. For a 5320 A pump wavelength, using a frequency-doubled neodymium laser, interferences can occur at very high soot densities. For N2 CARS, there are both incoherent and coherent components to the interference. The incoherent interference arises primarily from anti-Stokes fluorescence from C2 excited by Stokes laser absorption. The C2 is created by the laser vaporization of soot particulates, shown to occur even on a nanosecond time scale. The coherent interference arises most probably from electronically-resonantly enhanced wave mixing in the C2. Fortunately, neither interference is very large. By proper experimental design, interference-free CARS spectra from flame N2 can be obtained even at high soot densities. CARS signatures from N2 have been employed to map the temperature field with high spatial precision throughout a small, luminous, highly sooting, laminar propane diffusion flame. Single pulse (approx, 10 nanosecond) CARS thermometry has been demonstrated in various regions of a highly swireld, turbuelnt propane diffusion flame. Based upon these investigations, CARS continues to appear very promising for diagnostic applications to practical combustion sources.

• Research Organization: Purdue Univ., Lafayette, IN (USA). Project Squid Headquarters
• OSTI ID: 5709757
• Report Number(s): AD-A-069169
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
CARBON
CHEMICAL REACTIONS
COMBUSTION
COMPUTER CODES
CRYOGENIC FLUIDS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLAMES
FLUIDS
FLUORESCENCE
HYDROCARBONS
LASERS
LUMINESCENCE
NEODYMIUM LASERS
NITROGEN
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
PROPANE
RAMAN SPECTRA
SOLID STATE LASERS
SOOT
SPECTRA
THERMOCHEMICAL PROCESSES