Abstract: This talk will explore short pulsed microwave and laser based methods that provide new opportunities for control and analysis of complex flow fields. Micro: The natural ionization that is produced in flames provides a mechanism for high efficiency, localized energy deposition using KHz rate, microsecond long pulses of microwave radiation. Deposition of only ~3% of the power associated with a laminar methane-air flame leads to a 20% increase in the flame speed and a factor of two reduction of the lean combustion limit. Nano: The dynamic change in temperature in the flame zone is monitored with nanosecond pulsed filtered Rayleigh scattering, which provides a time frozen image of the temperature field. Pico: Nitric oxide production is monitored with picosecond Radar REMPI, which can also provide a localized measure of atomic species in the flame. Femto: Microwave coupling to femtosecond laser generated ionization provides a method for simultaneous ignition along a line. Microwave coupling to femtosecond laser ionization patterns also provides a method for localized energy addition for drag reduction and steering of supersonic objects and vehicles. The motion of high speed air can be monitored with Femtosecond Laser Electronic Excitation Tagging (FLEET). The figure below shows FLEET lines written across a vertical underexpanded supersonic air jet, providing instantaneous images of the velocity profile and a measure of the centerline velocity.

About the speaker...
Professor Miles received his Ph.D. in 1972 from Stanford University with a thesis in the area of nonlinear optics. He served on the faculty at Princeton from 1972 until his retirement in 2013, and continues to oversee his research group as a research staff member and Professor Emeritus. From 1980 to 1996 he served as Chair of Engineering Physics at Princeton. His research focuses on the use of lasers, electron beams, microwaves and magnetic devices to observe, control, accelerate, extract power and precondition gas flows for supersonic and hypersonic fluid dynamics, combustion, propulsion and homeland defense applications. His research group is widely recognized for inventing new linear and nonlinear optical diagnostics, developing new understanding of plasma aerodynamic and combustion interactions and exploring new concepts for hypersonic ground test facilities. Prof. Miles is a member of the National Academy of Engineering and a Fellow of the AIAA and the Optical Society of America. He serves on the Board of Directors of the Hertz Foundation, the Board of Trustees of Pacific University and the Air Force Scientific Advisory Board. He was the recipient of the AIAA Aerodynamics Measurement Award and Medal in 2000 and the AIAA Plasma Dynamics and Lasers Award and Medal in 2012.
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A special sundae bar reception will follow the lecture in the FXB Atrium
This event is free and open to the public