Spectroscopic Characterization of Solid Rocket Motor Plume Radiation

Abstract

To gather information about both particle and gas phase temperatures inside a scaled solid rocket motor plume UV-VIS emission spectroscopy (UVVIS) and infrared emission pectroscopy (FTIR) have been used. Additionally, a position resolving two-color pyrometer technique in the visible spectrum range (Alumina Emission Measurements, AEM) has been developed to obtain a particle temperature distribution of the whole plume. These three methods have been applied during the ESA-EMAP project tests inside DLR’s VMK facility of scaled solid rocket motor plumes. This project pursued activities regarding the experimental modeling of alumina particulates in solid boosters (EMAP). The UVVIS emission spectroscopy can be used to monitor the grey body radiation of the particle phase. This allows determining the particle phase temperature. FTIR spectroscopy allows the identification of gaseous species inside the plume such as CO2, CO, HCL and H2O. The emission lines of HCl can be used to determine the gas phase temperature of the plume. Both methods thus monitor the radiation intensity and the temperature over time at a certain position downstream the nozzle exit during the propellant combustion process. The AEM consists of two optical cameras which have been equipped with 10nm width optical bandpass filters to obtain intensity maps at two distinct wavelengths. The ratio of these intensity maps can be evaluated into a temperature distribution of the plume.