Swirling flow combustion - Fundamentals and application

Lewis, G. D.

doi:10.2514/6.1973-1250

Cited by 19 publications

(14 citation statements)

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“…Cross-sectional mass flow rate through circumferential cavityThe one major problem with the results presented thus far is the g-loading on the fluid in the circumferential cavity. For all test cases, with the exception of one of the 25% mass flow rate test cases, the g-load on the fluid well exceeded 7,500 g's, which both Lewis[3] and Zelina et al[2] reported to be the blow out limit for stoichiometric combustion. FromFigure 2.4 it can be seen that at an equivalence ratio of 2, on which the mass flow rate values were based, any g-loading value above…”

mentioning

confidence: 73%

“…This circumferential versus axial burning increases the g-loading on the fluid and provides two benefits. The first benefit is that combustion products burned under increased g-loading experience increased flame speeds as introduced by Lewis [3] in 1973. An increase in the reaction rate results in a decrease in the combustor volume.…”

Section: Ultra-compact Combustormentioning

confidence: 99%

“…The AFRL WSR was formed from two toroidal half sections made of cast zirconia-oxide separated by an Inconel R jet ring and placed inside a metal housing. The internal reactor volume formed by the two toroidal sections was 250 cm 3 .…”

Section: Test Setupmentioning

confidence: 99%

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Analysis of Flow Migration in an Ultra-Compact Combustor

Bohan

Polanka

2013

Journal of Engineering for Gas Turbines and Power

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The ultra-compact combustor (UCC) has the potential to offer improved thrust-to-weight and overall efficiency in a turbojet engine. The thrust-to-weight improvement is due to a reduction in engine weight by shortening the combustor section through the use of the revolutionary circumferential combustor design. The improved efficiency is achieved by using an increased fuel-to-air mass ratio and allowing the fuel to fully combust prior to exiting the UCC system. Furthermore, g-loaded combustion offers increased flame speeds that can lead to smaller combustion volumes. One of the issues with the UCC is that the circumferential combustion of the fuel results in hot gases present at the outside diameter of the core flow. These hot gases need to migrate radially from the circumferential cavity and blend with the core flow to present a uniform temperature distribution to the high-pressure turbine rotor. The current research focused on correlations to control the UCC cavity velocity, control the temperature profile throughout the UCC section, analyze the exhaust species exiting the combustor, and quantify pressure losses in the system. To achieve these goals, a computational fluid dynamics (CFD) analysis was used on a UCC geometry scaled to a representative fighter-scale engine. The analysis included a study of cavity to core flow interaction characteristics, a 5- and 12-species combustion model of liquid and gaseous fuel, and determination of species exiting the combustor. Computational comparisons were also made between an engine realistic condition and an ambient pressure rig environment.

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confidence: 73%

Section: Ultra-compact Combustormentioning

confidence: 99%

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Analysis of Flow Migration in an Ultra-Compact Combustor

Bohan

Polanka

2013

Journal of Engineering for Gas Turbines and Power

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“…Several experiments have been performed for understanding the effects of centrifugal forces on burning characteristics. Notably, the experiments of Lewis 6,7 clearly demonstrated the enhancement of flame speed to a value beyond that of a turbulent flame in the presence of centrifugal forces. Using a combustion-centrifuge device, he established centrifugal forces up to 10 4 ×g 0 and observed flame speeds up to nearly 4 times that of a conventional turbulent flame.…”

Section: Introductionmentioning

confidence: 95%

“…Here, g 0 represents earth's gravitational force. Some researchers such as Lewis 6,7 have proposed that g loading can increase flame speeds (thereby, flame stability) by a factor of 4. Present 2 study focuses on understanding the effects of g loading on flame structure in an effort to quantify any advantages or disadvantages for a UCC designed with high centrifugal forces.…”

Section: Introductionmentioning

confidence: 99%

Effect of Centrifugal Forces on Flame Stability in an Ultra-Compact Combustor

Katta

Blunck

Roquemore

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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The effects of centrifugal forces on flame structure in an Ultra Compact Combustor (UCC) were evaluated computationally. The UCC geometry was modified such that the centrifugal force can be applied as a source term in the momentum equation. This methodology has been validated through the simulation of a centrifuge experiment in which centrifugal forces were found to increase flame speeds. The "bubble transport" mechanism proposed by Lewis was identified in the centrifuge simulations. In hydrogen-air mixture at an equivalence ratio of 0.8, flame speed did not increase until a g loading of 10g 0 , at which point velocity of the buoyant flame packet reached the laminar burning velocity of 1.86 m/s. Further increase in g loading increased the flame speed along with the flame packet. Such "bubble transport" did not occur in UCC simulations. In laminar simulations, the strong velocity perpendicular to the centrifugal forces did not allow the flamelets to accelerate in the direction of buoyancy. Instead, the axial momentum increased and made the flame to become slightly thinner and elongated. In turbulent simulations, the small increase (~10%) in axial velocity did not change the flame structure significantly.

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Heat release and transfer of premixed propane/air flames in high g-load centrifugal force fields

Li²,

Wen³

2022

Fuel

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Swirling flow combustion - Fundamentals and application

Cited by 19 publications

References 0 publications

Analysis of Flow Migration in an Ultra-Compact Combustor

Analysis of Flow Migration in an Ultra-Compact Combustor

Effect of Centrifugal Forces on Flame Stability in an Ultra-Compact Combustor

Heat release and transfer of premixed propane/air flames in high g-load centrifugal force fields

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