EFFECTS OF SUPERCOOLING AND MELT PHENOMEMA ON PARTICULATE RADIATION IN PLUMES

IN THE EVALUATION OF HEAT LOADING DUE TO RADIATION EMITTED BY PARTICLES IN A SOLID ROCKET PLUME, THE EFFECTS OF PARTICLE SUPERCOOLING ON THE SUBMELT RADIATIVE CHARACTERISTICS ARE NOT WELL UNDERSTOOD. THIS PROJECT WILL EXPERIMENTALLY CHARACTERIZE THIS SUPERCOOLING PHENOMENON BY OBSERVING PARTICLE RADIATION DURING THE RAREFACTION WAVE COOLING OF SHOCK-HEATED AL2O3 PARTICLES. THE PHASE I EFFORTWILL PROVIDE NASA WITH QUANTITATIVE DATA FOR THE EFFECTS OF SUPERCOOLING ON THE OPTICAL PROPERTIES OF AL2O3, AND WILL DEFINE POTENTIAL PHASE II EFFORTS TO QUANTIFY OTHER HIGH-TEMPERATURE RADIATIVE EFFECTS AND TO DEVELOP EXPERIMENTAL CONCEPTS FOR VERIFICATION OF PREDICTIVE CODES. THE INNOVATIVE ASPECTS OF THE WORK LIE IN THE USE OF THE RAREFACTION WAVE IN A SHOCK TUBE TO SIMULATE PLUME SUPERCOOLING EFFECTS AND IN THE APPLICATION OF STATE-OF-THE-ART OPTICAL DIAGNOSTICS TO DETERMINE REFRACTIVE INDICES OF PARTICLES AT HIGH TEMPERATURES. IN THE EVALUATION OF HEAT LOADING DUE TO RADIATION EMITTED BY PARTICLES IN A SOLID ROCKET PLUME, THE EFFECTS OF PARTICLE SUPERCOOLING ON THE SUBMELT RADIATIVE CHARACTERISTICS ARE NOT WELL UNDERSTOOD. THIS PROJECT WILL EXPERIMENTALLY CHARACTERIZE THIS SUPERCOOLING PHENOMENON BY OBSERVING PARTICLE RADIATION DURING THE RAREFACTION WAVE COOLING OF SHOCK-HEATED AL2O3 PARTICLES. THE PHASE I EFFORTWILL PROVIDE NASA WITH QUANTITATIVE DATA FOR THE EFFECTS OF SUPERCOOLING ON THE OPTICAL PROPERTIES OF AL2O3, AND WILL DEFINE POTENTIAL PHASE II EFFORTS TO QUANTIFY OTHER HIGH-TEMPERATURE RADIATIVE EFFECTS AND TO DEVELOP EXPERIMENTAL CONCEPTS FOR VERIFICATION OF PREDICTIVE CODES. THE INNOVATIVE ASPECTS OF THE WORK LIE IN THE USE OF THE RAREFACTION WAVE IN A SHOCK TUBE TO SIMULATE PLUME SUPERCOOLING EFFECTS AND IN THE APPLICATION OF STATE-OF-THE-ART OPTICAL DIAGNOSTICS TO DETERMINE REFRACTIVE INDICES OF PARTICLES AT HIGH TEMPERATURES.