American Institute of Aeronautics and Astronautics 1 Reacting and Non-Reacting Flow Fields of a V-gutter Stabilized Flame Scott M. Bush * and Ephraim J. Gutmark † University of Cincinnati, Cincinnati, OH, 45221 Particle Imaging Velocimetry (PIV) measurements have been performed to determine the flow field around a confined V-gutter bluff body in both non-reacting and reacting environments. The PIV measurements capture instantaneous and mean flow structures formed in the wake region of a three dimensional bluff body. In addition to the flow structures, the mean velocity components, mean out of plane vorticity, and the turbulent kinetic energy have been compared between the non-reacting and reacting test cases. The results show significant differences in the instantaneous flow structures. The non-reacting case results in asymmetric shedding of large scale vortical structures that span the entire wake region while the reacting case results in both symmetric and asymmetric shedding of smaller scale vortical structures that are flattened out within the shear layer. A comparison of the mean velocity components clearly shows that the reacting case results in a larger region of reversed flow, experiences an acceleration of the freestream flow due to combustion, and results in a slower dissipation of the wake region. Nomenclature V x ,V y ,V z = mean streamwise, transverse, and spanwise velocity components v' x ,v' y ,v' z = fluctuating streamwise, transverse, and spanwise velocity components V b = bulk velocity: ω z = vorticity about the z-axis TKE = turbulent kinetic energy: D = V-gutter width T in = inlet temperature P s = static pressure Φ = equivalence ratio I. Introduction luff bodies placed in combustible high-speed flows are used to stabilize flames. Typical applications for bluff body stabilized flames include turbojet or turbofan afterburners in military aircraft, ramjet engines, and rocket motors. Bluff bodies stabilize flames by creating a large recirculation zone immediately downstream of the flame holding device. This recirculation zone consists of high temperature burnt products that act as a continuous ignition source for the fresh fuel/air mixture. A considerable amount of research has been conducted on bluff body stabilization, and comprehensive reviews of this topic can be found in references 1-5 . More recent research has investigated the flow fields around a bluff body in both the non-reacting and reacting environments. These studies focused on the characterization of the velocity field, turbulence, flow structures, temperature field, and species present in the wake region of the bluff body. The jet engine manufacturer, Volvo Flygmotor AB, has carried out an extensive experimental study 6-8 to gain insight into this complex, dynamic flow environment and to aid in the validation of CFD codes. All their experimental measurements were done with non- intrusive laser diagnostic techniques such as Laser Doppler Anemometry (LDA) and Coherent Anti-Stokes Raman Scattering (CARS). They reported doubling of the recirculation zone for reacting conditions compared to non- * Ph. D. Student, Department of Aerospace Engineering and Engineering Mechanics, 745 Baldwin Hall, Student Member AIAA. † Professor and Ohio Eminent Scholar, Department of Aerospace Engineering and Engineering Mechanics, 745 Baldwin Hall, Associate Fellow AIAA. B A m V b ρ / & = ) ( 2 2 2 2 1 z y x v v v TKE ′ + ′ + ′ = 44th AIAA Aerospace Sciences Meeting and Exhibit 9 - 12 January 2006, Reno, Nevada AIAA 2006-807 Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.