DEVELOPMENT OF A SUBMICRON MONODISPERSED AEROSOL GENERATOR FOR LASER DOPPLER VELOCIMETRY

SUPERCRITICAL FLUID NUCLEATION, THE PRINCIPLE EXPLOITED FOR THE DEVELOPMENT PROPOSED, HAS BEEN DEMONSTRATED FOR ITS ABILITY TO PRODUCE MONODISPERSE SUBMICRON PARTICLES OF VARIOUS ORGANIC AND INORGANIC COMPOUNDS. THE CONCEPT IS BASED UPON SOLUBILITY PHENOMENA IN SUPERCRITICAL FLUIDS, VIZ., THAT AT HIGH PRESSURE CERTAIN GASES CAN DISSOLVE ORGANIC COMPOUNDS AND THAT PARTICLES NUCLEATE WHEN THE PRESSURE ON THE GASEOUS SOLUTION IS LOWERED. BECAUSE THE RATE OF PRESSURE DECREASE CAN BE VARIED, PARTICLE SIZE CAN BE VARIED. IN SPECIFIC INSTANCES THE PRESSURE DECREASE CAN BE MADE TO OCCUR AT MILLIONS OF ATMOSPHERES PER SECOND, AND THUS, PARTICLE CAN BE FORMED IN THE 0.1 MICRON OR LESS SIZE RANGE. FURTHERMORE, BECAUSE OF THE RAPID CHANGE IN PRESSURE THAT CAN BE ACHIEVED, DISTRIBUTION IN PARTICLE SIZE IS ABSENT. COMPOUNDS FOR CONSIDERATION FOR THE STUDY HAVE MELTING POINTS BETWEEN 350 DEG TO 5500 DEG F AND THUS SATISFY THE REQUIREMENTS SOUGHT. AS A MEANS OF ASSESSING THE POTENTIAL FOR SUCCESSFUL COMPLETION OF A PHASE II EFFORT, THE PHASE I WORK INCLUDES A TASK DIRECTED TO THE DESIGN AND COST ESTIMATE OF A SMALL, SELF-CONTAINED AEROSOL GENERATOR.