Spectroscopic Study of Hot Gases

  • Firouz Shahrokhi
Part of the Developments in Applied Spectroscopy book series (DAIS, volume 7a)


This is a study to predict total heat flux from a hot gas utilizing spectroscopic properties of the gas. A system such as the chemical rocket-engine plumes serves as a pertinent example. The thermodynamic equilibrium assumption has been questioned for such high-energy systems. A flame which is chemically reacting and is radiating a large percentage of its energy is shown not to be representative of an equilibrium system. In the reaction zone there is certainly not an equilibrium situation, and even in the outer cone the carbon particles and the CO2 molecules do not appear to have time to equilibrate their energies. For these reasons an analysis of the radiation from a none- quilibrium flame is presented. The solution to the transport equation for an absorbing and emitting medium has been calculated based on a nonequilibrium gas. In this nonequilibrium state a measured spectroscopic intensity of volume emission of a given hot gas is presented and used, as well as the measured spectroscopic absorption coefficient. As in other branches of spectroscopy, the greatest emphasis has been placed on the measurement of spectral frequencies, because these frequencies are directly related to quantized energy levels of the flame molecules.


Optical Thickness Optical Path Length Volume Absorption Coefficient Total Heat Flux Experimental Flux 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.




limits of wavelength integration (µ)


distance from edge of flame to target (cm)


mean height of flame (cm)


monochromatic intensity (W cm−2 cm−1 S−1)


monochromatic volume emission (W cm-3 cm-1 S-l)


optical thickness of flame


monochromatic flux (W cm−2 cm−1)


mean radius of flame (cm)


temperature (Rankine degrees)


Gaussian quadrature integration weight factors


optical path length


monochromatic volume absorption coefficient (cm−1)


angle between normal to surface and central direction of the solid angle


solid angle (s)

σ, β, ϕ, ϒ

angles defined in extrapolation program



monochromatic quantities (wavelength)


quantities measured from flame with globar radiation incident


quantities measured from the flame


quantities measured from the globar


reference quantities


summing subscript


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Copyright information

© Chicago Section of the society for Applied Spectroscopy 1969

Authors and Affiliations

  • Firouz Shahrokhi
    • 1
  1. 1.UT Space InstituteTullahomaUSA

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