Integrated research of a multi-wavelength method in anisotropic scattering flame on soot temperature and radiative coefficient reconstruction.

Abstract

At present, the studies of scattering flame problems combined with multi-wavelength reconstruction technology are rather limited. In this paper, a multi-wavelength method combined with a collocation spectral method (CSM)-discrete ordinates method (DOM) forward method is developed for the simultaneous reconstruction of temperature and inhomogeneous radiative coefficient of an axisymmetric laminar ethylene diffusion flame. The scattering source term in the radiative transfer equation is solved by the forward solution method based on DOM, which couples a spatial scheme of CSM and the spherical rings arithmetic progression quadrature. The Tikhonov regularized method is employed to overcome the ill-posed matrix to obtain the global radiative source term. The boundary radiation intensity is input into the algorithm as a known value for inversion of temperature, absorption coefficient, and scattering coefficient. The retrieval results demonstrate that the temperature and the radiation parameters of the scattering flame can be well reconstructed for the flame with axisymmetric distribution, even for the flame with noisy data. In addition, the scattering coefficient is more difficult to rebuild than temperature. The inversion accuracy does not deteriorate with a slight increase in noise. Also, the addition of scattering terms to the proposed algorithm can improve the accuracy in reconstructing the radiation parameters. The developed method in this paper would be useful for multispectral algorithms, which could be used in later experiments based on hyperspectral techniques.