The problem of transient droplet vaporization in a hot convective environment is examined. The main objective of the present study is to develop an algorithm for the droplet vaporization which is simple enough to be feasibly incorporated into a complete spray combustion analysis and yet will also account for the important physics such as liquid-phase internal circulation, unsteady droplet heating and axisymmetric gas-phase convection. A simplified liquid-phase model has been obtained based on the assumption of the existence of a Hill's spherical vortex inside the droplet together with some approximations made in the governing diffusion equation. The use of the simplified model in a spray situation has also been examined. It has been found that droplet heating and vaporization are essentially unsteady and droplet temperature is nonuniform for a significant portion of its lifetime. It has also been found that the droplet vaporization characteristic can be quite sensitive to the particular liquid-phase and gas-phase models. The results of the various models are compared with the existing experimental data. Due to large scattering in the experimental measurements, particularly the droplet diameter, no definite conclusion can be drawn based on the experimental data. Finally, certain research problems which are related to the …

Chemical experiments were performed to examine the usefulness of heavy ion transfer reactions in producing new, neutron-rich actinide nuclides. A general quasi-elastic to deep-inelastic mechanism is proposed, and the utility of this method as opposed to other methods (e.g. complete fusion) is discussed. The relative merits of various techniques of actinide target synthesis are discussed. A description is given of a target system designed to remove the large amounts of heat generated by the passage of a heavy ion beam through matter, thereby maximizing the beam intensity which can be safely used in an experiment. Also described is a general separation scheme for the actinide elements from protactinium (Z = 91) to mendelevium (Z = 101), and fast specific procedures for plutonium, americium and berkelium. The cross sections for the production of several nuclides from the bombardment of {sup 248}Cm with {sup 18}O, {sup 86}Kr and {sup 136}Xe projectiles at several energies near and below the Coulomb barrier were determined. The results are compared with yields from {sup 48}Ca and {sup 238}U bombardments of {sup 248}Cm. Simple extrapolation of the product yields into unknown regions of charge and mass indicates that the use of heavy ion transfer reactions to produce …