Dynamic temperature measurements in the exhaust plume of an aluminized ammonium perchlorate composite propellant

Non-intrusive temperature diagnostic techniques were developed and implemented for measuring temperatures in rocket exhaust plumes during static firing. Ammonium perchlorate composite propellant (APCP) grains were cast and burn tested in a static rocket motor test facility. Temperature measurements in the exhaust plume were taken using two optical methods: Four-color pyrometry and ultraviolet-visible range (UV-VIS) spectroscopy. Using four bandpass optical filters at varying wavelengths, the four-color pyrometer measurements were used to infer temperature with reference to Planck's Law. A microHR spectrometer with a 300 groove/mm ruled grating with a range from 400 - 1400 nm was used to verify there were no instances that the bandpass filters chosen would interfere with any major emission features of the rocket plume. For the purposes of initial testing, the bandpass filters chosen were 550, 650, 700, and 800 nm based on published spectra. Temporally-resolved UV-VIS emission measurements were used to obtain the temperature history during the rocket firing events. The measured temperatures were compared to predicted combustion temperatures calculated using NASA chemical equilibrium and applications (CEA) software.