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10.27.15 Loth

66th NIA CFD Seminar:
OBSERVATION OF NOVEL DYNAMICS FOR A LOW-BOOM RELAXED-COMPRESSION SUPERSONIC INLET

Eric Loth, Chair MAE, University of Virginia
October 27, 2015, 11:00 am, NIA, Rm 141

Speaker Bio:
Dr. Eric Loth, the Chair of Mechanical and Aerospace Engineering (MAE) at the University of Virginia, is a PhD graduate of the University of Michigan. In 1990, he started as a faculty member at the University of Illinois, where he rose to the position of Professor, Willett Faculty Scholar, and Associate Head of Aerospace Engineering. In 2010, he joined the University of Virginia and later became its first Rolls-Royce Commonwealth Professor. Among many awards and distinctions, Dr. Eric Loth has been named a Fellow of the American Society of Mechanical Engineers, a Fellow of the National Center for Supercomputing Applications, and a Fellow at Magdalene College at Cambridge University. Research by Dr. Eric Loth and his students has resulted in more than 300 publications on a wide variety of topics including wind energy, unsteady aerodynamics, supersonic propulsion, multiphase flow, and micro-/nano-scale fluid dynamics.

Abstract:
The future of commercial supersonic flight requires low-boom aircraft design. To accomplish this, a relaxed-compression inlet design has been proposed and shown to dramatically reduce the shock signatures of the propulsion system. However, little is known about the unsteady fluid dynamics of such inlets, especially at or near on-design conditions. In the present study, it is shown that these dynamics are inconsistent with the dynamics of conventional supersonic inlets. The present study employed spectral analysis of a low-boom axisymmetric external compression inlet using Schlieren video and experimental unsteady surface pressure transducer readings as a function of mass flow rates. The experimental data was at Mach 1.67 in the 8’x6′ supersonic wind tunnel at the NASA Glenn Research Center. A 5 kHz sampling rate is used for surface pressure transducer readings while the shock motion was captured with Schlieren video frames at 2,000 frames per second, and processed using image-threshold analysis to determine fluctuations in external shock position. Power spectral density plots are used to reveal the dominant excitation modes for both the normal shock and surface pressure fluctuations. These fluctuations are minimal at the design mass flow rate case of 98.5% mass flow ratio (MFR) but became significant for a near-design MFR of about 95.5%. These pressure fluctuations were a strong function of pressure tap location and did not correspond to the conventional Ferri criterion of conventional supersonic inlets.
Additional information, including the webcast link, can be found at the NIA CFD Seminar website, which is temporarily located at http://www.hiroakinishikawa.com/niacfds/index.html.

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