ARTICLE:

• ON MEASURING THE MUELLER MATRIX ELEMENTS OF SOOT AGGLOMERATES  download article

R. Govindan
Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-0046, USA

S. Manickavasagam
Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-0108, USA

M. Pinar Menguc
Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-0108, USA

ABSTRACT

In this paper we present a methodology for measuring the elements of the Mueller (Scattering) matrix, which in turn can be used to determine the size of soot monomers and agglomerates in flames. The experimental system to be used is composed of two linear polarizers, two quarter wave plates and a half wave plate along with a light source (Nd:YAG Laser). The preliminary independent parameters in this setup are the polarizer angles ξ₁, ξ₂ and the retarder angles β₁, β₂ and β₃, which can be varied to obtain different condition numbers (CN). If the CN is large, then the Mueller matrix elements determined from experiments would not be reliable. However by using a proper set of ξ and β values, one can reduce the CN to be less than 10. This concept is discussed for different fractal-like soot agglomerates. It is shown that even if there is ± 7.5 % error in measured intensities, the recovered S₁₁ and S₁₂ elements are virtually identical to the true values. These S_ij elements can be used in an inverse algorithm to identify the size of soot monomers and agglomerates.

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