Structure of Plumes from Burning Aluminized Propellant Estimated Using Fan Beam Emission Tomography

Abstract

Fan beam emission tomography in the 1–5-� m band is used to estimate the structure of a solid rocket propellant plume. Fan beam emission tomography consists of two components. The first is a pair of orthogonal high-speed imaging spectrometers and scanners that measures the spectral radiation intensities from 1.3 to 4:8 � m at 256 view angles. The second is a robust deconvolution algorithm that estimates the structure of the plume from the spectral radiation intensity measurements. The deconvolution algorithm is based on the maximum likelihood estimation method in conjunction with a linearized radiative transfer equation. The radiation intensity measurements were completed in a series of burns using 2.5-cm-diam by 1.25-cm-long strands of aluminized solid rocket composite propellant.Ingeneral,thealuminumdiffusion-flameparticulatetemperaturesintheplumearemuchhigherthanthe gastemperatures.Thegaseouscombustionproductconcentrationsaremuchlowerinthemiddleoftheplumethanat the outer edges. This indicates a diffusion-flame-type structure for the plume, caused by the fact that the composite solid rocket propellant isfuel-rich. Theresults indicate thatreliable plume-structure measurements can be obtained using fan beam emission tomography. Nomenclature d = diameter of the burning surface, cm