On Flame Stabilization by Bluff-Bodies

Kundu, Krishnendu; Banerjee, Debanjan; Bhaduri, D.

doi:10.1115/1.3230225

Cited by 40 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, Kundu et al's. [100,101] measurements show a monotonic reduction of temperature in the recirculation zone as the flow velocity increases toward its blowoff value. They found that the ratio of wake to adiabatic flame temperature decreased from 0.94 to 0.88 as U/U LBO increased from 0.3 to 0.9.…”

Section: Discussionmentioning

confidence: 94%

“…Since entrainment rates scale as D/U (see Section 2.2.2) then it follows that this criterion reduces to a Damkö hler number blowoff criterion, using a chemical time that is derived from the well stirred reactor, s PSR . A similar idea relates to an energy balance between heat supplied by the hot recirculating flow to the fresh gases and that released by reaction [98,[100][101][102]. In this view, blowoff occurs when the heat required by the combustible stream exceeds that received from the recirculation zone.…”

Section: Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Lean blowoff of bluff body stabilized flames: Scaling and dynamics

Shanbhogue

Husain

Lieuwen

2009

Progress in Energy and Combustion Science

543

206

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 98%

Lean blowoff of bluff body stabilized flames: Scaling and dynamics

Shanbhogue

Husain

Lieuwen

2009

Progress in Energy and Combustion Science

543

206

View full text Add to dashboard Cite

“…LBO scaling as a function of combustion parameters (incoming flow velocity, equivalence ratio, pressure, temperature, and fuel type) have been reported for specific combustor configurations [9][10][11][12][13][14], and active or passive control strategies to extend LBO have been explored [8,[15][16][17][18]. Several LBO mechanisms have been proposed and include balance between the rate of entrainment of reactants into the recirculation zone and the rate of buming [19], energy balance between heat supplied by the hot recirculating flow to the fresh gases and that released by reaction [20][21][22][23], balance between contact time between the combustible mixture and hot gases in the shear layer and chemical ignition time [20,[24][25][26], and mecha-nisms related to local extinction by excessive flame stretch with a flamelet based description [27][28][29]. In addition, it is believed that flame front instabilities play important roles in the blowout process in view of the reported observations of flame pulsations and flicker before the flame actually blows out [30,31].…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study of Lean Blowout With Hydrogen-Enriched Fuels

Zhu

Acharya

2012

Journal of Engineering for Gas Turbines and Power

View full text Add to dashboard Cite

premixed combustion is widely used to achieve a better compromise between nitric oxide (NOx) emissions and combustion efficiency (related to CO levels). However, com-bustor operation near the lean blowout (LBO) limit can render the flame unstable and lead to oscillations, flashback, or extinction, thereby limiting the potential range of lean combustion application. Recent interest in integrated gasification combined cycle plants and syngas combustion requires an improved understanding of the role of hydrogen on the combustion process. Therefore, in the present study, combustion of pure methane and blended methane-hydrogen with hydrogen-levels up to 80 % by volume has been con-ducted in a swirl stabilized premixed combustor. Particle imaging velocimetry (PIV) and OH * chemiluminescence imaging have been used in this study. Results show that there is a single-ringed structure of internal recirculation zone (IRZ) in the non-reacting flow, while in the reacting flows, there is a more complex flow pattern with a two-celled IRZ structure in which the axial velocity near the center-axis is oriented downstream. As the equivalence ratio decreases, the width of IRZ decreases in methane flames while it increases in hydrogen-enriched flames, and the flame shape changes from conical to an elongated columnar shape, especially in hydrogen-enriched flames. There are two differ-ent modes of vortex breakdown observed, spiral mode in methane flames and bubble mode in hydrogen-enriched flames. These differences between the behavior of the methane-only and hydrogen-enriched flames lead to different behavior of the flame as it approaches the lean blowout. The differences in the mechanisms of LBO in pure methane and hydrogen-enriched premixed flames are examined and explained in the present study. [DOI: 10.1115/1.4004742

show abstract

“…The usefulness of the mass-weighted velocities is explained in the description of Eqns. (1) and (2). The mass-weighted velocity does not coincide with the flow velocity itself.…”

Section: Stability Curve Of Bluff-body Stabilized Flamesmentioning

confidence: 99%

“…The relation between flame structure and flame stability was identified. Kundu et al [2] investigated flame stabilization by bluff-bodies to highlight the role of the recirculation zone. They observed that close correlations exist between heat exchange from the recirculation zone and flame stability, which were controlled by the strength of recirculation.…”

Section: Introductionmentioning

confidence: 99%

The Characteristic Modes and Structures of Bluff-Body Stabilized Flames in Supersonic Coflow Air

Kim

Yoon

Park

et al. 2012

International Journal of Aeronautical and Space Sciences

View full text Add to dashboard Cite

The stability and structure of bluff-body stabilized hydrogen flames were investigated numerically and experimentally. The velocity of coflowing air was varied from subsonic velocity to a supersonic velocity of Mach 1.8. OH PLIF images and Schlieren images were used for analysis. Flame regimes were used to classify the characteristic flame modes according to the variation of the fuel-air velocity ratio, into jet-like flame, central-jet-dominated flame, and recirculation zone flame. Stability curves were drawn to find the blowout regimes and to show the improvement in flame stability with increasing lip thickness of the fuel tube, which acts as a bluff-body. These curves collapse to a single line when the blowout curves are normalized by the size of the bluff-body. The variation of flame length with the increase in air flow rate was also investigated. In the subsonic coflow condition, the flame length decreased significantly, but in the supersonic coflow condition, the flame length increased slowly and finally reached a near-constant value. This phenomenon is attributed to the air-entrainment of subsonic flow and the compressibility effect of supersonic flow. The closed-tip recirculation zone flames in supersonic coflow had a reacting core in the partially premixed zone, where the fuel jet lost its momentum due to the high-pressure zone and followed the recirculation zone; this behavior resulted in the long characteristic time for the fuel-air mixing.

show abstract

On Flame Stabilization by Bluff-Bodies

Abstract: Flame stabilization by bluff-bodies has been investigated to highlight the role of recirculation zone on the phenomenon. It has been observed that close correlations exist between heat exchange from recirculation zone and flame stability as controlled by recirculation strength.

Cited by 40 publications

References 0 publications

Lean blowoff of bluff body stabilized flames: Scaling and dynamics

Lean blowoff of bluff body stabilized flames: Scaling and dynamics

An Experimental Study of Lean Blowout With Hydrogen-Enriched Fuels

The Characteristic Modes and Structures of Bluff-Body Stabilized Flames in Supersonic Coflow Air

Contact Info

Product

Resources

About