Acquisition of a High-Pulse-Energy, Narrow-Linewidth, UV Laser Source: Improved Quantitative Gas-Phase Mixing Measurements in Turbulent Spray Flows

Ohio State University, The, Columbus OH

Investigators

Abstract

1336913 Sutton This project involves the acquisition of components to assemble an ultra-high-pulse-energy (300 mJ/pulse at 254 nm), tunable, narrow-linewidth (~ 30 MHz) UV laser system. This instrument will be the primary component used within a UV filtered Rayleigh scattering (FRS) measurement system to investigate vaporization and gas-phase mixing processes within turbulent spray flows. Subsequent experiments using the new UV laser and FRS system will target gas-phase thermometry in sooting hydrocarbon flames which will yield new information concerning soot transport and reaction chemistry. Perhaps the best known examples of turbulent sprays exist in energy conversion systems in which a liquid fuel issues into an oxidizing environment, evaporates, and mixes with the oxidizer before reacting. Gas-phase mixing has not been studied extensively in multi-phase spray environments primarily due the co-existence of the liquid phase that makes the independent measurement of the vapor-phase concentration very difficult. The PI will use the new high-energy UV laser (254 nm) in conjunction with an atomic mercury filter to perform UV FRS measurements for quantitative gas-phase measurements with minimal interference from the liquid-phase droplets. Broader impacts of the project are addressed by the fact that the majority of engineering systems operate with working mediums that consist of multiple phases. In particular, spray flows are of significant interest in many applications including automotive engines, liquid-propellant rocket engines, industrial furnaces, and gas-turbines. With a better understanding of the vaporization and gas-phase mixing processes, improvements in fuel injector and combustor design will be possible, resulting in an improved control over ignition and a potential for increased efficiency, increased stability, and decreased pollutant emissions. In terms of research-related education, the proposed laser system will be used by post-doctoral researchers and undergraduate/graduate students to enhance their training in state-of-the art measurement techniques. Our technological future depends on developing both new methodologies and a new workforce capable of tackling such complicated problems.