Enhancing combustion in a dump combustor using countercurrent shear. Part 2: Heat release rate measurements and geometry effects

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

Abstract

Research to advance our understanding of the countercurrent shear flow has been conducted, with particular emphasis on those characteristics of countercurrent shear that are beneficial for combustion applications. Studies carried out in a backward-facing step combustor burning prevaporized JP10-air mixtures, have examined the implementation of counterflow as a means to enhance turbulent burning velocities, with the overall objective of increasing volumetric heat release rates and thereby create a more compact combustion zone. The dump combustor is characterized by a nominally two-dimensional primary flow mixture of prevaporized fuel and air, entering a rectangular channel before encountering a 2:1 single-sided step expansion. Flow separation over the sudden expansion and the resulting recirculation set up a countercurrent shear layer downstream of the dump plane and a low velocity zone conducive to flame anchoring. Combustion control strategies aim to increase turbulent kinetic energy and flame three-dimensionality in an effort to increase flame surface area and thus burning rates. A secondary flow is created via suction at the dump plane as a fluidic control mechanism to enhance the naturally occurring countercurrent shear layer. Counterflow is shown to elevate turbulence levels and volumetric heat release rates downstream of the step in the base geometry while concomitantly reducing the scale of the recirculation zone[1]. Modifications to the rearward-facing step geometry are investigated using Particle Image Velocimetry (PIV) under isothermal flow conditions in an effort to extend the near field interaction between the recirculation zone and the incoming primary flow, thus exploiting the benefits of counterflow as seen in the base geometry. Using chemiluminescence, relative heat release rates are shown to increase by 90% with a counterflow level of 6% of the primary flow by mass in the base geometry, and a 150% increase with a counterflow level of 2.4% in the modified step geometry.

Original languageEnglish (US)
Title of host publicationProceedings of the ASME Heat Transfer Division 2005
Pages347-354
Number of pages8
Edition1
DOIs
StatePublished - Dec 1 2005
Event2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005 - Orlando, FL, United States
Duration: Nov 5 2005Nov 11 2005

Publication series

NameAmerican Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD
Number1
Volume376 HTD
ISSN (Print)0272-5673

Other

Other2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005
CountryUnited States
CityOrlando, FL
Period11/5/0511/11/05

Keywords

  • Combustion
  • Countercurrent shear flow
  • Shear layer
  • Turbulence
  • Volumetric heat release

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    Hoxie, A. B., Anderson, M. J., Strykowski, P. J., & Forliti, D. J. (2005). Enhancing combustion in a dump combustor using countercurrent shear. Part 2: Heat release rate measurements and geometry effects. In Proceedings of the ASME Heat Transfer Division 2005 (1 ed., pp. 347-354). (American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD; Vol. 376 HTD, No. 1). https://doi.org/10.1115/IMECE2005-81274