Effect of Combustor Inlet Geometry on Acoustic Signature and Flow Field Behavior of the Low Swirl Injector

Therkelsen, Peter; Littlejohn, David; Cheng, R.K.; Portillo, J. Enrique; Martin, Scott M.

doi:10.1115/gt2010-23498

Cited by 7 publications

(5 citation statements)

References 18 publications

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“…The mean velocity, U/Uo, in the inner region (r/R,, < 0.6) is less than the velocity through the outer region (r/R" > 0.6). The turbulence intensity u'/Uo is relatively uniform in the inner region, around 10%, but increases to 40% around r/R" = 1, indicating the presence of a shear layer at the bumer rim [26].…”

Section: Resultsmentioning

confidence: 99%

Flashback and Turbulent Flame Speed Measurements in Hydrogen/Methane Flames Stabilized by a Low-Swirl Injector at Elevated Pressures and Temperatures

Beerer¹,

McDonell

Therkelsen³

et al. 2013

Journal of Engineering for Gas Turbines and Power

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This paper reports flashback limits and turbulent flame local displacement speed measurements in flames stabilized by a low swirl injector operated at elevated pressures and inlet temperatures with hydrogen and methane blended fuels. The goal of this study is to understand the physics that relate turbulent flame speed to flashback events at conditions relevant to gas turbine engines. Testing was conducted in an optically accessible single nozzle combustor rig at pressures ranging from 1 to 8atm, inlet temperatures from 290 to 600 K, and inlet bulk velocities between 20 and 60 m/s for natural gas and a 90%/10% (by volume) hydrogen/methane blend. The propensity of flashback is dependent upon the proximity ofthe lifted flame to the nozzle that is itself dependent upon pressure, inlet temperature, and bulk velocity. Elashback occurs when the leading edge of the flame in the core of the flow ingresses within the nozzle, even in cases when the flame is attached to the burner rim. In general the adiabatic flame temperature at flashback is proportional to the bulk velocity and inlet temperature and inversely proportional to the pressure. The unburned reactant velocity field approaching the flame was measured using a laser Doppler velocimeter with water seeding. Turbulent displacement flame speeds were found to be linearly proportional to the root mean square of the velocity fluctuations about the mean velocity. Eor identical inlet conditions, high-hydrogen flames had a turbulent flame local displacement speed roughly Mice that of natural gas flames. Pressure, inlet temperature, and flame temperature had surprisingly little effect on the local displacement turbulent flame speed. However, the flow field is affected by changes in inlet conditions and is the link between turbulent flame speed, flame position, and flashback propensity.

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Section: Resultsmentioning

confidence: 99%

Flashback and Turbulent Flame Speed Measurements in Hydrogen/Methane Flames Stabilized by a Low-Swirl Injector at Elevated Pressures and Temperatures

Beerer¹,

McDonell

Therkelsen³

et al. 2013

Journal of Engineering for Gas Turbines and Power

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“…The vane shape did not affect the swirling flow appreciably but the curved-vane LSI had a much lower pressure drop [12]. The interaction of the recirculation zone and shear layer with both hydrocarbon and high-hydrogen content flames has been observed to form noticeable acoustic effects which can lead to severe combustion instabilities [13]. It has been identified that vortex shedding from the nozzle rim to be a major contributor to the acoustics [13].…”

Section: Introductionmentioning

confidence: 99%

Flame lift-off height control by a combined vane-plasma swirler

Jiang

Chen

et al. 2018

J. Phys. D: Appl. Phys.

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In this study, a swirler combining the vane swirler and the plasma swirler is designed to control the flame lift-off height. The plasma swirler is located near the rim of the injector and the vane swirler is placed upstream of the plasma swirler. The vane swirler is employed to form a divergent flow to sustain the detached flame and the plasma swirler is adopted to control the flame lift-off height. The ionic wind clinging to the inner wall of the injector tube does not penetrate into the center, leaving the main stream flow in the central region largely undisturbed. Characteristics of the flow field are analyzed from the results of laser Doppler anemometry (LDA) measurement and mechanism of the flame lift-off control by the combined vane-plasma swirler is revealed. The flame lift-off locations calculated from the LDA measurement are consistent with those from direct observation. The dielectric barrier discharge (DBD) voltage influences the height of the flame lift-off with a linear relationship observed, which means the flame lift-off height can be controlled precisely by the DBD voltage without any mechanical movement or changing the mass flow rate. The combined vane-plasma swirler has the potential to improve the fuel flexibility, increase flame stability and attenuate the injector overheating. Highlights 1. A combined vane-plasma swirler is designed to control the flame lift-off height. 2. Flame lift-off height can be adjusted by changing the voltage of the dielectric barrier discharge. 3. A linear relationship between flame lift-off height and the dielectric barrier discharge voltage is observed. 4. Flame lift-off control by the combined vane-plasma swirler is mainly associated with the aerodynamic effect. 5. The swirler can improve fuel flexibility, increase flame stability and attenuate injector overheating.

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“…Heat losses to the chamber walls are also known to alter the structure of the reacting flow [11,12]. A central bluff-body [2,13,14] and a diffuser [2,4,13,[15][16][17] constitute other widely used elements to enhance the stabilization of swirling flames. In high power systems, it is, however, more suitable to operate without any central insert to reduce the thermal stress on the solid components of the injector.…”

Section: Introductionmentioning

confidence: 99%

Effects of a Diverging Cup on Swirl Number, Flow Pattern, and Topology of Premixed Flames

Degenève

Jourdaine

Mirat

et al. 2018

Journal of Engineering for Gas Turbines and Power

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Impact of the diverging cup angle of a swirling injector on the flow pattern and stabilization of technically premixed flames is investigated both theoretically and experimentally with the help of OH* chemiluminescence, OH laser-induced fluorescence and particle image velocimetry (PIV) measurements. Recirculation enhancement with a lower position of the internal recirculation zone (IRZ) and a flame leading edge protruding further upstream in the swirled flow are observed as the injector nozzle cup angle is increased. A theoretical analysis is carried out to examine whether this could be explained by changes of the swirl level as the diffuser cup angle is varied. It is shown that pressure effects need in this case to be taken into account in the swirl number definition and expressions for changes of the swirl level through a diffuser are derived. It is demonstrated that changes of the swirl level including or not the pressure contribution to the axial momentum flux are not at the origin of the changes observed of the flow and flame patterns in the experiments. The swirl number without the pressure term, designated as pressure-less swirl, is then determined experimentally with laser Doppler velocimetry (LDV) measurements at the injector outlet for a set of diffusers with increasing quarl angles under nonreacting conditions and the values found corroborate the predictions. It is finally shown that the decline of axial velocity and the rise of adverse axial pressure gradient, both due to the cross section area change through the diffuser cup, are the dominant effects that control the leading edge position of the IRZ of the swirled flow. This is used to develop a model for the displacement of the recirculation bubble as the quarl angle varies that shows very good agreement with experiments.

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Effect of Combustor Inlet Geometry on Acoustic Signature and Flow Field Behavior of the Low Swirl Injector

Cited by 7 publications

References 18 publications

Flashback and Turbulent Flame Speed Measurements in Hydrogen/Methane Flames Stabilized by a Low-Swirl Injector at Elevated Pressures and Temperatures

Flashback and Turbulent Flame Speed Measurements in Hydrogen/Methane Flames Stabilized by a Low-Swirl Injector at Elevated Pressures and Temperatures

Flame lift-off height control by a combined vane-plasma swirler

Effects of a Diverging Cup on Swirl Number, Flow Pattern, and Topology of Premixed Flames

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