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Speaker: Tim Lieuwen
Affiliation: Georgia Institute of Technology

Abstract: This seminar will describe theoretical and experimental work on combusting wake flows.  Combustion instabilities are strongly controlled by the features of the acoustically excited, vortically induced velocity field that wrinkles the flame.  We will discuss, first, the influence of heat release on the hydrodynamic stability of bluff body wakes and, second, how external forcing, such as would occur during a combustion instability, influences the forced response of the unstable wake.  In addition, we show how the receptivity of the unstable flow to forcing profoundly influences the heat release response of the flame.  In particular, we show that forcing the flame at frequencies close to the natural hydrodynamic instabilities can actually cause a reduction in global heat release fluctuations.  This is a significant result that challenges conventional notions–in other words, aligning the frequency of an acoustic mode with that of a hydrodynamic mode is not automatically problematic, and in some cases can actually reduce the heat release response amplitude relative to its response at other frequencies.

Biosketch: Tim Lieuwen is a professor and the David S. Lewis, Jr. Chair at Georgia Institute of Technology, and the Executive Director of the Strategic Energy Institute.  He has a Ph.D. in mechanical engineering and is a licensed professional engineer in the state of Georgia.  He leads a diverse research group investigating a range of problems associated with clean power, energy, and combustion, including such issues as emissions, efficiency, and alternative fuels.  Prof. Lieuwen has edited/written four books, written 7 book chapters and over 300 papers, and received 5 patents.

Date/Time:
Date(s) - Nov 16, 2017
4:00 pm - 5:00 pm

Location:

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