Radiative heat transfer analysis with molten Al₂O₃ dispersion in solid rocket motors

Radiative heat transfer by alumina smoke particles (molten Al ₂O₃) in aluminized solid rocket motor internal flowflelds has been investigated by computational simulation. The issue of how to define the alumina dispersion's radiative properties has been addressed to be compatible with existing radiative transfer equation solvers. Individual particle radiative properties, which are nongray and anisotropicin scattering, are evaluated from fundamental particle scattering theory for spheres (i.e., Mie theory) and optical constants from the literature, including temperature and spectral dependence. An integration procedure over wavelength has been implemented to make use of the effective gray form of two common radiative transfer equation solvers: the finite volume method and Rosseland diffusion radiation model. The internal flowfield has been modeled including turbulent multiphase flow with inert radiating particles using commercial computational fluid dynamics software. The simulation has been exercised for a subscale solid rocket motor, the75-lbballistic test and evaluation systems motor. Simulation results show that the bulk of the internal flowfield (the core flow) is very optically thick, so much so as to be amenable to Rosseland diffusion modeling.