Optimization of the Mixing Quality of a Real Size Gas Turbine Burner With Instantaneous Planar Laser-Induced Fluorescence Imaging

Krämer, H.; Dinkelacker, Friedrich; Leipertz, Alfred; Poeschl, Gerwig; Huth, Michael; Lenze, Martin

doi:10.1115/99-gt-135

Cited by 10 publications

(8 citation statements)

References 8 publications

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“…But also flow instabilities, fluctuating recirculation zones [17], fluctuating flame fronts [31,19] and unsteady air-fuel mixing are possible mechanisms [12,18,20,32]. As discussed by Krämer et al [8] and Schildmacher et al [24], the time averaged spatial mixing may be quite perfect but temporal fluctuations degrade the mixing quality and may significantly compromise the NO x emissions [15]. The fluctuations of the mixing can be attributed to flow instabilities, e.g.…”

Section: Introductionmentioning

confidence: 96%

Experimental Characterization of Premixed Flame Instabilities of a Model Gas Turbine Burner

Schildmacher

Koch

Bauer

2006

Flow Turbulence Combust

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In recent years, the NO x emissions of heavy duty gas turbine burners have been significantly reduced by introducing premixed combustion. These highly premixed burners are known to be prone to combustion oscillations. In this paper, investigations of a single model gas turbine burner are reported focusing on thermo-acoustic instabilities and their interaction with the periodic fluctuations of the velocity and pressure. Phase-locked optical measurement techniques such as LDA and LIF gave insight into the mechanisms.Detailed investigations of a gas turbine combustor rig revealed that the combustor as well as the air plenum oscillate in Helmholtz modes. These instabilities could be attributed to the phase lag of the pressure oscillations between the air plenum and the combustor, which causes an acceleration and deceleration of the air flow through the burner and, therefore, alternating patterns of fuel rich and lean bubbles. When these bubbles reach the reaction zone, density fluctuations are generated which in turn lead to velocity fluctuations and, hence, keep up the pressure oscillations.With increasing the equivalence ratio strong combustion oscillations could be identified at the same frequency. Similarly as with weak oscillations, Helmholtz mode pressure fluctuations are present but the resulting velocity fluctuations in the combustor can be described as a pumping motion of the flow. By the velocity fluctuations the swirl stabilization of the flame is disturbed. At the same time, the oscillating pressure inside the combustor reaches its minimum value. Shortly after the flame expands again, the pressure increases inside the combustor. This phenomenon which is triggered by the pressure oscillations inside the air plenum seems to be the basic mechanism of the flame instability and leads to a significant increase of the pressure amplitudes.

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Section: Introductionmentioning

confidence: 96%

Experimental Characterization of Premixed Flame Instabilities of a Model Gas Turbine Burner

Schildmacher

Koch

Bauer

2006

Flow Turbulence Combust

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“…The definition of mixing uniformity is shown in Equation () 4 . The mixing uniformity of the six cases was calculated at the distance of 40 mm from the outlet of the swirler2.…”

Section: Numerical Simulation Resultsmentioning

confidence: 99%

“…Generally, the physical boundary conditions include the classification mode of fuel and air, the air distribution in the main combustion zone, the fuel distribution (FD) mode, and so forth, while the geometric boundary conditions include the fuel jet structure, premixed section structure, swirl intensity, and so forth 2 . The premixing process has been carefully designed for the existing advanced dry low‐emission combustors in the world, such as DLN2.6 combustor of GE and HR3 combustor of Siemens to ensure better mixing uniformity of fuel and air 3,4 . The common feature is that the fuel is preinjected into the air through many small holes on the air mixing mechanism, the incoming air has considerable swirl and turbulence intensity, and has a long enough premixed distance 5…”

Section: Introductionmentioning

confidence: 99%

Study on combustion performance of microgas turbine combustor with different fuels

Liu

Xinci

et al. 2023

Energy Science & Engineering

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A low‐pollution single‐tube microgas turbine combustor using different gas fuels was studied. The combustion performance of two kinds of landfill gas and natural gas was tested in a single‐head combustor. The effects of fuel nozzle position, and the fuel distribution ratio between pilot and main combustion stage on pollutant emission were investigated under rated load condition. The flow field, temperature field, and pollutant generation characteristics with different fuel nozzle diameters and nozzle positions were analyzed by numerical simulation. The results show that: the combustor can form an obvious central recirculation zone, which is convenient for ignition and stable flame propagation; in the case of limited premixed length, the influence of fuel nozzle position on fuel–air mixing uniformity is less obvious than that of fuel nozzle diameter. The fuel–air mixing uniformity plays a decisive role in the temperature field and the generation of pollutants in the combustor. The combustor has good pollutant emission characteristics, and the NOx emission can be reduced to about 10 ppmv (15% O2 concentration) under the appropriate combination of fuel nozzle diameter and position, which provides a reference for the further optimization of low‐emission combustor.

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“…In combustion chambers with equivalence ratios less than 1, a poor mixing process between the gaseous fuel and air may lead to the richer gas pockets generating more significant local formation of NO x [23]. During the chemical processes, the heterogeneities of a reactive mixture can alter the purity of the desired product by modifying the selectivity of the reaction.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Investigation of the Influence of the Wake Behind an Injector Frame on Jet Dilution in a Crossflow

Gourara

Rogér

Wang

2005

Flow Turbulence Combust

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In this paper, a mixing of gases through square Jets issuing normally Into a CrossFlow (JICF) is investigated by means of both numerical simulation and experiment. The jets are emitted by two injectors mounted at the top and bottom of an Injector Frame (IF) which is installed at the center of an Eiffel type wind-tunnel. This jet configuration makes it possible to approximate an industrial gas mixer placed at the center of a pipe. Large Eddy Simulation based on the Smagorinsky model is used, enabling characterization of the mean and fluctuating velocities as well as the oscillating flow frequencies. Different diagnostic techniques, such as Laser Doppler Anemometry and Particle Image Velocimetry are employed for validating the numerical models, and a good agreement between prediction and experiment is obtained. In the numerical simulation, introduction of a passive scalar through the jet makes it possible to show three dilution phenomena. They are generated respectively by the wake of the IF, the jet/wake assemblage and the jets alone in function of the momentum flux ratio between jet and crossflow. Influence of the various parameters on the mixing process between the jets and the crossflow is identified. The numerical results show that if the IF wake is suppressed with the presence of a trailing edge behind the IF, classical formation of Counter-rotating Vortex Pair is found. NomenclatureC = Smagorinsky constant D = characteristic length (m) Esd = energy spectral density (m 2 s −1 ) F = frequency (Hz) g = gravity vector (m s −2 ) J = ρ jet U 2 jet ρ cf U 2 cf : momentum flux ratio between jet and crossflow M k = molar mass of the species k (kg mol −1 ) p = pressure (Pa) R = ideal gas constant (J mol −1 K −1 ) Re cf = U cf D jet ν cf : Reynolds number built on U cf and D jet 356 A. GOURARA ET AL. Re inj = U cf D inj ν cf : Reynolds number built on U cf and D inj Re jet = U jet D jet ν jet : Reynolds number built on U jet and D jet R v = velocity ratio between jet and crossflow S i j = large scale strain rate tensor (s −1 ) |S i j | = magnitude of the large scale strain rate tensor (s −1 ) Sc t = turbulent Schmidt number St = F D U : Strouhal number t = time (s) T = temperature (K) Tu = ( u 2 1 +u 2 2 +u 2 3 3U 2 cf ) 0.5 : turbulence rate U = (u 1 , u 2 , u 3 ): velocity vector (m s −1 ) U = bulk velocity (m s −1 ) x = (x 1 , x 2 , x 3 ) ≡ (x, y, z) : coordinates (m) Y k = mass fraction of the species k = filter size (m) = Von Karman vortex magnitude (m) ν = kinematic viscosity (m 2 s −1 )Y k 3 ): subgrid scalar transport flux of the species k (kg m −2 s −1 ) Subscripts and Superscripts 0 = operating conditions cf = crossflow cl = centerline CVP = counter-rotating vortex pair inj = injector frame (IF) jet = jet max = maximum sg = subgrid scales te = trailing edge VK = Von Karman vortices behind the IF Operators = filter ∼ = Favre filter = time averaging operator

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Optimization of the Mixing Quality of a Real Size Gas Turbine Burner With Instantaneous Planar Laser-Induced Fluorescence Imaging

Cited by 10 publications

References 8 publications

Experimental Characterization of Premixed Flame Instabilities of a Model Gas Turbine Burner

Experimental Characterization of Premixed Flame Instabilities of a Model Gas Turbine Burner

Study on combustion performance of microgas turbine combustor with different fuels

Numerical and Experimental Investigation of the Influence of the Wake Behind an Injector Frame on Jet Dilution in a Crossflow

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