Convective and absolute instabilities in reacting bluff body wakes

Benjamin Emerson, Julia Lundrigan, Jacqueline O'Connor, David Noble, Tim Lieuwen

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

This paper describes the variation of bluff body wake structure with flame density ratio. It is known that the bluff body flow structure at "high" and "low" flame density ratios is fundamentally different, being dominated by the convectively unstable shear layers or absolutely unstable Von Karman vortex street, respectively. This paper characterizes the aforementioned transition and shows that the bifurcation in flow behavior does not occur abruptly at some ρub value. Rather, there exists a range of transitional density ratios at which the flow exists intermittently in both flow states, abruptly shifting back and forth between the two. The fraction of time that the flow spends in either state is a monotonic function of ρub. This behavior is to be contrasted with lower Reynolds number, laminar flow problems where the convective/absolute instability transition occurs at a well defined value of bifurcation parameter. With this distinction in mind, however, this paper also shows that local parallel stability analyses developed for laminar base wake flows can capture many of the observed flow dependencies. These results have important implications on the dynamics of high Reynolds number, vitiated flows, where typical parameter values fall into the highly intermittent flow regime characterized in this study. This suggests that such flows exhibit two co-existing dynamical states, intermittently jumping between the two.

Original languageEnglish (US)
Title of host publicationASME 2011 Turbo Expo
Subtitle of host publicationTurbine Technical Conference and Exposition, GT2011
Pages377-387
Number of pages11
EditionPARTS A AND B
DOIs
StatePublished - 2011
EventASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, GT2011 - Vancouver, BC, Canada
Duration: Jun 6 2011Jun 10 2011

Publication series

NameProceedings of the ASME Turbo Expo
NumberPARTS A AND B
Volume2

Other

OtherASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, GT2011
CountryCanada
CityVancouver, BC
Period6/6/116/10/11

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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