K-Distribution Analysis of Gas Radiation With Nongray, Emitting, Absorbing, and Anisotropic Scattering Particles

Abstract

The K-distribution technique is presented for predicting nongray gas radiation in the presence of particle scattering. This technique transforms the otherwise formidable spectral integration problem from the frequency domain to the K or gas absorption coefficient domain. This transformation is made possible by the negligible variation of blackbody intensity and particle radiative properties with frequency within a gas band. Application of the K-distribution technique to an isothermal emission problem is made. Results are compared with those from the Monte-Carlo method, These results show that, with the K-distribution technique, the detailed absorption line structure within a gas band as well as the scattering effect due to particles can be simulated with great numerical accuracy and computational efficiency. Essentially, line-by-line accuracy is achieved without line-by-line spectral integration.