Title:

Ultrashort Pulse Laser Imaging Diagnostics for Combustion, Propulsion, and Plasma Applications

Speaker:

Prof. Waruna Kulatilaka

Affiliation:

Texas A&M University

When:

Friday, April 18, 2025 at 2:00:00 PM   Add to Calendar

Where:

MRDC Building, Room 4211

Host:

Ellen Mazumdar
ellen.mazumdar@gatech.edu

Abstract

Advances in ultrashort-pulse, kHz–MHz-rate laser diagnostics have enabled novel approaches for non-intrusive, multi-dimensional imaging of chemical species in reacting flows. Such diagnostics unravel basic physio-chemical processes in fundamental flames and plasmas, and have applications in practical gas turbine combustors, hypersonic propulsion systems, and energetic material reactions and explosions. The first part of this talk will focus on developing femtosecond (fs) laser-based fluorescence imaging techniques for atoms and molecules in gas-phase reacting flows. In particular, ultrashort, femtosecond laser-induced fluorescence (fs-LIF) methods have enabled interference-free, kHz-rate imaging of highly reactive atomic species such as H, O, and N, molecules such as OH, NO, CO, and O2, and inert tracers such as Kr and Xe in combustion and plasma systems. Several major milestones in the last decade will be highlighted, followed by a discussion on the latest developments in simultaneous multi-species imaging using a single fs laser source. A specific application to carbon-free fuels such as ammonia and hydrogen will be highlighted. The second half of the talk will focus on recent efforts in characterizing the production and evolution of H and O atoms in repetitively pulsed nanosecond plasma discharges using fs two-photon LIF (fs-TPLIF). This study reveals, for the first time, the spatial extent of these reactive radicals and their evolution governed by hydrodynamic processes of consecutive discharges, shedding new light into plasma-assisted combustion in supersonic engines.

Biography

Dr. Waruna Kulatilaka (Ku. La. Ti. La. Ka) is the Holdredge/Paul Professor in J. Mike Walker Department of Mechanical Engineering with a joint courtesy appointment in the Department of Aerospace Engineering at Texas A&M University. His research is focused on advanced optical and laser-based diagnostics for fundamental combustion and plasma studies, as well as for a range of applications in propellants and energetics, hypersonics, and ultra-high-rate material impact characterization. His research team was the first to develop femtosecond two-photon laser-induced fluorescence (fs-TPLIF) imaging for highly reactive chemical species such as H, O, and N atoms in flames. Dr. Kulatilaka has also contributed to multiple other laser diagnostic techniques, including LIF, CARS, polarization spectroscopy, and LIBS. His research contributions are reported in nearly 100 peer-reviewed journal articles, over 250 conference papers and presentations, and numerous national and international invited talks. Dr. Kulatilaka serves as the Associate Department Head for Undergraduate Programs in Mechanical Engineering and is active in multiple committees of professional organizations such as ASME, AIAA, and the International Combustion Institute-CI (Chair of the Central States Section of the CI). He is a Fellow of ASME, an Associate Fellow of AIAA, and a Senior Member of Optica.

Notes

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