Systematic work will be initiated in the diagnostics of swirling liquid spray flames. To date, the measurement of swirling flows has been performed mostly with gaseous fuels. Measurement of liquid sprays has been restricted to simple atomizers spraying liquids into quiescent environments. Detailed data of drop size, drop velocity, particle number density, and size-velocity correlations have never been measured in swirling isothermal or combusting liquid sprays. The objectives are to determine the effect of swirl on the turbulent mixing of liquid spray particles and their response to the swirling flow, and to determine the effect of swirl on the formation of the toroidal vortex core and its effect on the spray. Advanced laser-based diagnostic techniques will be developed specifically aimed at investigating the properties of liquid sprays in combusting swirling flows. The dynamics properties of the liquid sprays will be determined; these are key to flame stabilization and pollutant formation and will lead to optimization of overall combustion efficiency, with applications to internal combustion engines, gas turbine, and furnace design.