Review of Chemiluminescence as an Optical Diagnostic Tool in High Pressure Unstable Rockets

The purpose of this project was to investigate the effects of optical absorption on line-of-sight integrated chemiluminescence measurements in high pressure rockets. The use of chemiluminescent emissions has been used in the past in an effort to characterise the flame reaction zone and the corresponding heat release, however most efforts have been with low pressure or atmospheric flames. Chemiluminescent measurements have been used in the case of the Continuously Variable Resonant Combustor (CVRC) in an attempt to validate a CFD simulation of the same system, although the CVRC operates at a higher pressure. For higher pressure flames it is unclear if such measurements are valid. To bridge the gap between the experimental and numerical data a spectroscopic model was created to study the validity of chemiluminescent based measurements in the CVRC. It was found that the CVRC combustion medium is optically opaque for the chemiluminescent emissions produced by OH* and optically transparent for the chemiluminescent emissions produced by CH*. Unfortunately, the emissions produced by CH* are largely influenced by the emissions produced by CO 2*. As such, both OH* and CH* are poor indicators of the heat release in the CVRC and therefore chemiluminescence measurements are not useful in validating the CVRC CFD simulation