Effect of the Acoustic Excitation on Lean Blowoff in Turbulent Premixed Bluff Body Flames

2014 ◽  
Author(s):  
Chanyeong Jeong ◽  
Jaeik Shin ◽  
Youngbin Yoon
Keyword(s):  
Bluff Body ◽  
Acoustic Excitation ◽  
Turbulent Premixed

Effect of Acoustic Excitation on Lean Blowoff in Turbulent Premixed Bluff Body Flames

2015 ◽  
Vol 188 (1) ◽  
pp. 55-76 ◽  
Author(s):  
Chanyeong Jeong ◽  
Jaeik Shin ◽  
Jeongjae Hwang ◽  
Jisu Yoon ◽  
Youngbin Yoon
Keyword(s):  
Bluff Body ◽  
Acoustic Excitation ◽  
Turbulent Premixed

Effects of Acoustic Excitation on a Swirling Diffusion Flame

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Michael E. Loretero ◽  
Rong F. Huang
Keyword(s):  
Flow Field ◽  
Bluff Body ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Mie Scattering ◽  
Flame Length ◽  
Laser Doppler Velocimeter ◽  
Scattering Method ◽  
Acoustic Excitation ◽  
Characteristic Modes

A swirling double concentric jet is commonly used for nonpremixed gas burner application for safety reasons and to improve the combustion performance. Fuel is generally spurted at the central jet while the annular coflowing air is swirled. They are normally separated by a blockage disk where the bluff-body effects further enhance the recirculation of hot gas at the reaction zone. This paper aims to experimentally investigate the behavior of flame and flow in a double concentric jet combustor when the fuel supply is acoustically driven. Laser-light sheet assisted Mie scattering method has been used to visualize the flow, while the flame lengths were measured by a conventional photography technique. The fluctuating velocity at the jet exit was measured by a two-component laser Doppler velocimeter. Flammability and stability at first fuel tube resonant frequency are reported and discussed. The evolution of flame profile with excitation level is presented and discussed, together with the reduction in flame length. The flame in the unforced reacting axisymmetric wake is classified into three characteristic modes, which are weak swirling flame, lifted flame, and transitional reattached flame. These terms reflect their primary features of flame appearances, and when the acoustic excitation is applied, the flame behaviors change with the excitation frequency and amplitude. Four additional characteristic modes are identified; e.g., at low excitation amplitudes, wrinkling flame with a blue annular film is observed because the excitation induces vortices in the central fuel jet and hence gives rise to the wrinkling of flame. The central jet vortices become larger with the increase in excitation amplitude and thus lead to a wider and shorter flame. If the excitation amplitude is increased above a certain value, the central jet vortices change the rotation direction and pacing with the annular jet vortices. These changes in the flow field induce large turbulent intensity and mixing and therefore make the flame looks blue and short. Further increase in the excitation amplitude would lift the flame because the flow field would be dramatically modified.

scholarly journals Vortex Phase-Jitter in Acoustically Excited Bluff Body Flames

2009 ◽  
Vol 1 (3) ◽  
pp. 365-387 ◽  
Author(s):  
Santosh J. Shanbhogue ◽  
Michael Seelhorst ◽  
Tim Lieuwen
Keyword(s):  
Heat Release ◽  
Bluff Body ◽  
Axial Direction ◽  
Harmonic Excitation ◽  
Acoustic Excitation ◽  
Phase Jitter ◽  
Image Velocimetry ◽  
Flow Field Characteristics ◽  
Spatially Periodic ◽  
Phase Phase

This paper describes an experimental study of the effect of acoustic excitation on bluff body stabilized flames, specifically on the flow field characteristics. The Kelvin-Helmholtz (KH) instability of the shear layer is excited due to the incident acoustics. In turn, the KH instability imposes a convecting, harmonic excitation on the flame, which leads to spatially periodic flame wrinkling and heat-release oscillations. Understanding the factors influencing these heat release oscillations requires an understanding of the generation, convection, and dissipation of these vortical disturbances. Phase locked particle image velocimetry was carried out over a range of conditions to characterize the vortical dynamics. It was found that the vortex core location exhibits “phase jitter”, manifested as cycle-to-cycle variation in flame and vorticity field at the same excitation phase. Phase jitter is shown to be a function of separation point dynamics, downstream convection time, and amplitude of acoustic excitation. It leads to fairly significant differences between instantaneous and ensemble averaged flow fields and, in particular, the decay rate of the vorticity in the axial direction.

scholarly journals On the bi-stable nature of turbulent premixed bluff-body stabilized flames at elevated pressure and near lean blow-off

2020 ◽  
Author(s):  
Aaron W. Skiba ◽  
Thibault F. Guiberti ◽  
Wesley R. Boyette ◽  
William L. Roberts ◽  
Epaminondas Mastorakos
Keyword(s):  
Bluff Body ◽  
Elevated Pressure ◽  
Stabilized Flames ◽  
Turbulent Premixed

Blow-off mechanism in a turbulent premixed bluff-body stabilized flame with pre-vaporized fuels

2019 ◽  
Author(s):  
Rohit S. Pathania ◽  
Aaron Skiba ◽  
Jennifer A. Sidey ◽  
Epaminondas Mastorakos
Keyword(s):  
Bluff Body ◽  
Turbulent Premixed

scholarly journals Simulations and experiments on the ignition probability in turbulent premixed bluff-body flames

2016 ◽  
Vol 20 (3) ◽  
pp. 548-565 ◽  
Author(s):  
Michael Philip Sitte ◽  
Ellen Bach ◽  
James Kariuki ◽  
Hans-Jörg Bauer ◽  
Epaminondas Mastorakos
Keyword(s):  
Bluff Body ◽  
Ignition Probability ◽  
Turbulent Premixed

Grid Convergence Studies of Bluff Body Stabilized Turbulent Premixed Combustion

2017 ◽  
Author(s):  
Adam L. Comer ◽  
Swanand V. Sardeshmukh ◽  
Brent A. Rankin ◽  
Matthew E. Harvazinski ◽  
Venke Sankaran
Keyword(s):  
Bluff Body ◽  
Premixed Combustion ◽  
Turbulent Premixed Combustion ◽  
Grid Convergence ◽  
Turbulent Premixed
Sign in / Sign up

Export Citation Format

Share Document