Experimental and computational studies of volumetric radiation

An experimental and computational methods of predicting volumetric radiation in participating media are accomplished. The problems of radiation from a gas turbine combustor and from a solid rocket motor plume were addressed during this study. In the case of a gas turbine combustor the objectives were: (1) to demonstrate proper procedures for making band-pass-filtered total radiometer measurements on a combustor, (2) to assess how well such measurements would agree with predictions based on engineering correlations of gas and soot radiation, (3) to discover how to use the measurements to indicate effective radiant temperatures of the gas and soot and soot loading, and (4) to determine the mass absorption coefficient of soot. It is shown that comparing band-pass-filtered total radiometer measurements with predictions of the recently modified version of an existing engineering model, GASMIX II, can help determine the effective gas and soot temperatures and soot loading. An experimental method was used to determine the value of the mass absorption coefficient of soot independent of its optical properties. For solid rocket motor plume radiation the objective was to develop engineering models that compromise between simplicity/utility and realism. For a motor firing into a vacuum, a radiation model, PARRAD, has been developed to calculate the radiation to aft-end equipment and the directional variation of the motor plume intensity. It is shown how the critical parameters of the model can be fixed from engineering experiments and how other less critical parameters can be set reasonably. The PARRAD model was extended to PARRAD II to include nongray particles and gases. Parametric calculations were made. It is shown that gas and soot have little influence upon solid rocket motor plume radiation, which is dominated by alumina particle emission and scattering. Nozzle wall radiation is significant near the exit if the nozzle wall temperature exceeds 1200 K. Afterburning has a large effect by maintaining high particle temperatures and high plume intensity downstream of the exit. Directional variations in the plume boundary intensity are small when the scattering optical depth due to small particles is large. Finally, suggestions are made for improving phenomenological models for solid rocket plume radiation.