ADVANCED FLOW DIAGNOSTICS APPLIED TO SUPERSONIC JET NOISE
K. Todd Lowe, NIA Visitor and Assistant Professor, Dept. of Aerospace and Ocean Engineering, Virginia Tech
August 15, 2014, 11:00 am, NIA, Rm 101
Hosts: Cathy McGinley and Dan Neuhart (NASA Langley)
Abstract:
Innovative instruments are needed for understanding the noise-producing turbulent events in supersonic aircraft plumes. Useful techniques must share a few common traits, including portability for use in facilities throughout the country, high data density to minimize run times, robustness to minimize setup and calibration times, resolution of the demanding spatio-temporal scales that occur in the flows of interest, and little or no instrument-specific rig modifications. Laser instrumentation relying upon particle scattering has been developed under the ONR Hot Jet Noise Reduction Basic Research Challenge program for non-intrusive, multi-point measurements of turbulent flow velocity in plumes with supersonic eddy convection at very high repetition rates. Such an instrument is only possible with the latest photonics technologies of high power single-line mode tunable lasers, ultra-sensitive photodetector arrays, and high bandwidth/high throughput data acquisition. In the talk, the fundamental development and subsequent applications of this Doppler-based instrument capable of 100 kHz bandwidth velocimetry will be discussed. Particular attention will be paid to the types of measurements being obtained to study the fundamental mechanisms for noise production in supersonic shear layers, such as eddy convective velocity.
Bio:
Dr. Todd Lowe is an assistant professor in the Department of Aerospace and Ocean Engineering at Virginia Tech, where he also earned a Ph.D. in 2006. His research in experimental fluid mechanics leverages applied laser diagnostics developed in his laboratory for high sampling rate measurements of turbulent shear flows. The primary applications of his research are the gas turbine propulsion and wind turbine renewable energy fields, supported by companies in both these industries as well as NASA/NIA and the Office and Naval Research.