Analysis of mechanisms and the nature of radiation from aluminum oxide in different phase states in solid rocket exhaust plumes

Absorption Coefficient of Molten Aluminum Oxide in Semitransparent Spectral Range

“…Figure 1 shows the calculation results for the dependence of the absorption coefficient  on the wavelength at these temperatures, made on the basis of data of reference (Parry & Brewster, 1991). In reference (Anfimov, Karabadjak, Khmelinin, Plastinin, & Rodionov, 1993), the authors, based on the results of their own measurements in the range from 0.2 µm to 7 µm, present empirical expressions for four items of the absorption index of molten Al 2 O 3 :  0  1  2  3 . The first item is determined by the contribution of atoms vibrations, the second -by the contribution of free electrons, the third -by the fundamental absorption band of bound electrons (absorption in the UV region due to interband transition of electrons), and the fourth -by the Urbach long-wavelength edge of absorption of this band.…”

“…No details of obtaining of these empirical expressions are given, and the initial data for the emissivity of droplets from chemically pure Al 2 O 3 that are on the tungsten disc, are not presented either. The approach suggested by Anfimov et al (1993) was further developed by Plastinin et al (2000) in the paper published later. The coefficients are specified for the items of the absorption index of molten Al 2 O 3 and argumentation is given for selection of empirical parameters.…”

“…One is that in the course of solidification a crystalline -phase is formed, which after further cooling transfers very rapidly into an equilibrium -phase (Levi et al, 1988;Anfimov et al, 1993;Plastinin et al, 2000). The other view is that in the course of the rapid crystallization a two-phase extended zone is formed (Vorobyev et al, 2001;Vorob'ev et al, 2007).…”

High Altitude Plume Simulations for a Solid Propellant Rocket

“…This model is strongly coupled to the flowfield simulation, and allows for spectrally resolved radiation calculations in an emitting, absorbing and scattering medium of arbitrary optical thickness. 6 Following simulations of Anfimov et al, 13 the Al 2 O 3 particle phase is assumed to account for 30% of the mass flow at the nozzle exit, and is made up of seven discrete particle sizes ranging from 0.3 to 6 µm in diameter. Properties for each particle size are independently specified along inflow boundaries at the nozzle exit plane.…”

“…These inflow properties, as well as those of the gas, are taken from a nozzle flow simulation by the same authors. Due to a lack of available flowfield information at the nozzle exit, most particle properties given by Anfimov et al 13 are assumed uniform over the exit plane. The one exception is in the initial particle directions; for both particles and gas, bulk velocities along the nozzle exit plane are set to scale linearly with distance from the axis.…”