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RESEARCH PAPERS: Solution Methods

Spectral Module for Photon Monte Carlo Calculations in Hypersonic Nonequilibrium Radiation

[+] Author and Article Information
Takashi Ozawa

Aerospace Research and Development Directorate, Japanese Aerospace Exploration Agency, Chofu, Tokyo 182–8522 Japantakashi@chofu.jaxa.jp

Michael F. Modest

Shaffer and George Professor of Engineering, Science and Engineering Building, Rm. 392 University of California, Merced, CA 95343MModest@eng.ucmerced.edu

Deborah A. Levin

Department of Aerospace Engineering, Pennsylvania State University, University Park, PA 16802dalevin@engr.psu.edu

J. Heat Transfer 132(2), 023406 (Dec 09, 2009) (8 pages) doi:10.1115/1.4000242 History: Received December 19, 2008; Revised April 24, 2009; Published December 09, 2009; Online December 09, 2009

Abstract

In this paper, efficient spectral modules and random number databases are developed for atomic and diatomic species for use in photon Monte Carlo (PMC) modeling of hypersonic nonequilibrium flow radiation. To model nonequilibrium flow conditions, the quasisteady state assumption was used to generate electronic state populations of atomic and diatomic gas species in the databases. For atomic species (N and O), both bound-bound transitions and continuum radiation were included and were separately databased as a function of electron temperature and number density as well as the ratio of atomic ion to neutral number density. For the radiating diatomic species of $N2+$, $N2$, $O2$, and NO databases were generated for each electronic molecular electronic system. In each molecular electronic system, the rovibrational transition lines were separately databased for each electronic upper state population forming the electronic system. The spectral module for the PMC method was optimized toward computational efficiency for emission calculations, wavelength selections of photon bundles and absorption coefficient calculations in the ray tracing scheme.

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Figures

Figure 1

Line index database of k1 and k2 as a function of wavelength for N

Figure 2

Line index database of k1 and k2 as a function of wavelength (left) and spectral normalized emission lines and accumulated lines at temperatures of 5000 K (right) for N2+(1−) transition molecular electronic system

Figure 3

Comparison of spectral emission of atomic species between spectral module and NEQAIR results

Figure 4

Comparison of emission and ∇⋅q of N and O gas mixture along the stagnation line between the PMC and TS (NEQAIR)

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