Predictions of near exit plane spectral radi- ance are made with CHARM 1.3 and compared with a unique set of vacuum plume measurements from solid propellant rockets. Two propellants are used, a nomi- nal 15 percent and a low 2 percent Al-loading. A small research motor with three nozzles was used. These noz- zles included a conical and a contoured expansion with area ratios of 40 and a conical expansion with an area ratio of 10. Spectra between about 1.9 and 5.2 gm along with some gas dynamic measurements were ob- tained. Predictions agree with measurements near the exit plane for the low Al-propellant which is very nearly like a purely gaseous plume. Predictions for the nominal Al-propellant are greater than the measure- ments near the exit plane. It is suggested that CHARM overpredicts the particle temperatures in the nozzle. The utility of simple research-like tests to validate plume signature codes is emphasized.
B. E. Pearce,
"Dynamic end-to-end model tested for IR detection algorithms", Proc. SPIE 1725, Targets, Backgrounds, and Discrimination, 172507 (29 January 1991); doi: 10.1117/12.2300207; https://doi.org/10.1117/12.2300207