Flame Stabilization and Role of von Karman Vortex Shedding Behind Bluff Body Flameholders

Khosla, Sachin; Leach, Timothy T.; Smith, Clifford E.

doi:10.2514/6.2007-5653

Cited by 20 publications

(11 citation statements)

References 5 publications

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“…Many previous flameholding studies have been performed where the flow is everywhere subsonic [2][3][4][5] and for flows where the core flow is everywhere supersonic [6][7][8], but the measurements generally do not provide relevant quantitative data for dual-mode combustor designs. Examples of important differences include the following: 1) Inflow turbulence levels and flow unsteadiness are significantly higher in the dual-mode combustor where a shock train is located upstream of the flameholder.…”

Section: Introductionmentioning

confidence: 99%

Dual-Mode Scramjet Flameholding Operability Measurements

Donohue

2014

Journal of Propulsion and Power

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Measurements were made in a direct-connect combustor facility designed to simulate cavity flameholding in a hydrocarbon-fueled dual-mode scramjet combustor where the presence of a shock train upstream of the flameholder has a significant impact on the inlet flow to the combustor and on flameholding limits. A mechanical throttle was installed in the downstream end of the test rig to provide the backpressurization needed to form the shock train and to decouple the operation of the flameholder from the backpressure formed by heat release and thermal choking, as it would be in a flight engine. The flameholding limits were measured by ramping inlet air temperature down until blowout was observed. The test facility used a vitiated air heater, Mach 2.2 and 3.3 inlet nozzles, a 0.65-in.-deep cavity, and ethylene and heated JP-7 fuel. A Mean blowout temperature of 1502°R was measured at the baseline condition which used a Mach 2.2 inlet, a cavity pressure of 21 psia, and ethylene fuel. The blowout temperature was found to be most sensitive to fuel injection location and fuel flow rates, and relatively insensitive to inlet Mach number and operating pressure. Video imaging showed unsteady flame structures with significant movements laterally and upstream of the flameholder.

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Section: Introductionmentioning

confidence: 99%

Dual-Mode Scramjet Flameholding Operability Measurements

Donohue

2014

Journal of Propulsion and Power

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“…The results shown that von Karman vortex shedding did not influence the http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014. 11.031 0017-9310/Ó 2014 Elsevier Ltd. All rights reserved. blowout condition; because the flame extinction occurred at the same equivalence ratio.…”

Section: Introductionmentioning

confidence: 96%

“…Kiel et al [10] studied the bluff-body flames near blowout and they asserted that the larger von Karman vortices dynamics were the dominant mechanism to flame extinction. But Khosla [11] compared the blowout condition on bluffbody with and without von Karman vortex shedding. The results shown that von Karman vortex shedding did not influence the http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.…”

Section: Introductionmentioning

confidence: 99%

Size effect on the flame base locations after V-gutters for premixed flames

Gong

Huang

2015

International Journal of Heat and Mass Transfer

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“…But Khosla [6] concluded that both configurations with and without von Karman vortex shedding blow out at the same premixed equivalence ratio, thus indicating that the effect of von Karman eddies on blowout may not be significant.. Kiel et al [13] used numerical simulation method to predict the blowout based on Da theory. They found τ flow =k/ε would reach the minimum in the boundary layer near bluff body, so under the same conditions the flame here was easy to be extinguished.…”

Section: Introductionmentioning

confidence: 99%

A numerical investigation on the mechanism of bluff-body lean blowout

Gong

Huang

Wang

et al. 2013

2013 International Conference on Materials for Renewable Energy and Environment

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In order to control the NOx pollutant emissions and reduce fuel consumption, lean combustion becomes an important subject. A bluff body is used in this paper to study the flame-holding mechanism by numerical simulation. After the validation of the numerical method, 6 cases were simulated with different inlet velocity of the premixed mixture of kerosene vapor and air. The responses of reaction rate near blowout to inlet velocity variation were analyzed. The results show that with the increase of the inlet flow velocity, the anchoring points move upstream to the bluff body, while nearly no movement along the cross direction, and the flame will finally be blown out if the anchoring points are almost attached to the bluff body. It is implied that the quenching effect caused by heat transfer between flame fronts and bluff body is the key factor of flame blowout. Keywords-bluff body numerical simulation anchoring point flame holding lean blowout

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Flame Stabilization and Role of von Karman Vortex Shedding Behind Bluff Body Flameholders

Cited by 20 publications

References 5 publications

Dual-Mode Scramjet Flameholding Operability Measurements

Dual-Mode Scramjet Flameholding Operability Measurements

Size effect on the flame base locations after V-gutters for premixed flames

A numerical investigation on the mechanism of bluff-body lean blowout

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