Speaker: Dr. Douglas Fletcher
Professor, Department of Mechanical Engineering
University of Vermont
douglas.fletcher@uvm.edu

 

 

Recent progress in determining quantitative surface reaction rates from spatially resolved measurements of reactive species and temperature will be presented. These measurements are made in the University of Vermont 30 kW Inductively Coupled Plasma Torch Facility using single- and two-photon laser-induced fluorescence to probe species in the nonequilibrium thermal boundary layer over different material surfaces. Example species gradient distributions will be used to illustrate the method for determining the surface reaction rates. Recent results from tests done with planar imaging will be presented, as this improves testing efficiency for different sample materials. Finally, recent tests to capture the transient material response of an ultra-high-temperature ceramic material in air plasma using multiple spectroscopic instruments will be presented.

 

Dr. Douglas Fletcher is Professor of Mechanical Engineering at the University of Vermont, with a secondary appointment in Materials Science. He earned a BS in Engineering from the University of Vermont and completed his MS in Mechanical Engineering and PhD in Mechanical and Aerospace Engineering at the University of Virginia under the supervision of Prof. James McDaniel.

Dr. Fletcher joined the Experimental Fluid Dynamics Branch at NASA Ames Research Center to develop laser diagnostic techniques for measuring turbulent flow fluctuations in high-speed compressible flows. He later moved to the Reacting Flow Environments Branch, where he led efforts to characterize plasma flows in large-scale arc-jet facilities. His work used laser spectroscopy to quantify the kinetic, thermal, and chemical enthalpy of the free stream during air-plasma testing.

In 2000, Dr. Fletcher joined the Aeronautics and Aerospace Department at the von Karman Institute for Fluid Dynamics, where he led research on laminar-to-turbulent transition in hypersonic flows and the development of nonintrusive plasma diagnostics. He served as Head of the Aeronautics and Aerospace Department from July 2004 until January 2007, when he joined the Mechanical Engineering Department at UVM. He served as Department Chair from 2020 to 2026.

In 2009, Dr. Fletcher and his students constructed UVM’s 30 kW Inductively Coupled Plasma Torch Facility, integrating optical diagnostics with the plasma test chamber. The facility has been used to evaluate a wide range of candidate thermal-protection materials, from solid ceramics to woven fibers. It has also provided quantitative measurements of surface-catalyzed reaction rates, carbon nitridation, and nitrogen recombination on high-temperature graphite.

Dr. Fletcher is an Associate Fellow of the American Institute of Aeronautics and Astronautics.