Effect of burner geometry on swirl stabilized methane/air flames: A joint LES/OH-PLIF/PIV study

Liu, X.; Elbaz, Ayman M.; Gong, Chen; Bai, Xue‐Song; Zheng, Hongtao; Roberts, William L.

doi:10.1016/j.fuel.2017.06.092

Cited by 33 publications

(13 citation statements)

References 44 publications

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“…The swirl generated by the swirler can strengthen flame stabilizing, control flame size and combustion intensity, decrease NO formation by improving the mixing of fuel and air [30][31][32]. The divergent conical nozzle technology can obtain highly stabilized flames which can be seen in previous studies [33][34][35][36]. Moreover, the convergent passage can further enrich the mixing of fuel and air to lower the pollutant emissions.…”

Section: Experimental Apparatusmentioning

confidence: 74%

An Experimental Investigation on the NO and CO Emission Characteristics of a Swirl Convergent-divergent Nozzle at Elevated Pressure

et al. 2018

Energies

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The behavior of the pollutants NO and CO at elevated combustor pressure are of special importance due to the continuing trend toward developing engines operating at higher pressure ratios to yield higher thermal efficiency. An experiment was performed to examine the NO and CO emissions for a swirl convergent-divergent nozzle at elevated pressure. The NO and CO correlations were obtained. Meanwhile, the flame length, exhaust gas oxygen concentration, exit temperature and global flame residence time were also determined to analyze the NO and CO emission characteristics. The results showed that, with the increase in combustor pressure P, flame length decreased proportionally to P −0.49 ; exit O 2 volume fraction increased and exit temperature was reduced. The global flame residence time decreased proportionally to P −0.43. As pressure increased, the NO and Emission Index of NO (EINO) levels decreased proportionally to P −0.53 and P −0.6 respectively, which is mainly attributed to the influence of global flame residence time; the NO and EINO increased almost proportionally with the increase in global flame residence time. The EINO scaling EINO (ρu e /d) was proportional to Fr 0.42 , which indicated that compared with pure fuel, the fuel diluted with primary air can cause a decrease in the exponent of the Fr power function. At higher pressure, the CO and Emission Index of CO (EICO) decreased proportionally to P −0.35 and P −0.4 , respectively, due to the increased unburned methane and high pressure which accelerated chemical reaction kinetics to promote the conversion of CO to CO 2 .

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Section: Experimental Apparatusmentioning

confidence: 74%

An Experimental Investigation on the NO and CO Emission Characteristics of a Swirl Convergent-divergent Nozzle at Elevated Pressure

et al. 2018

Energies

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“…This result is typical in swirling upstream with a central bluff body since the majority of the mass flow is passing close to the walls, hence, the central regime has low velocity [24]. Figure 4 shows the distribution of the OH* mass fraction since this variable closely related to the heat release rate [25] and is easy to measure [26]. A stable V-shaped flame was formed in each case.…”

Section: Methodsmentioning

confidence: 91%

Numerical analysis of biogas combustion in a lean premixed swirl burner

Füzesi

Józsa

2019

2019 7th International Youth Conference on Energy (IYCE)

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Modern combustion technology focuses on lean premixed burners to achieve high thermal efficiency, wide operating range, and low pollutant emissions for steady-state operation. The corresponding applications range from boilers to gas turbines. The present paper is a preliminary analysis of a turbulent laboratory test burner with 30 kW combustion power by using CFD. The reference fuel was natural gas and four biogases were tested which were modeled as a mixture of CH 4, CO2, and H2 in various compositions. Even though the combustion is steady, the steady solution was inappropriate due to the notable presence of unsteady flow structures. Since the combustion in the present case is dominated by volumetric reactions, a coarse boundary layer could be applied near the wall. However, the shear-dominated flow required the use of at least k-ω SST turbulent viscosity model. The transient cases were calculated by using Scale Adaptive Simulation. Among the fuels, natural gas combustion showed flashback due to the bluff body present at the center in the mixing tube inlet. Nevertheless, its extent was low and some central purge air in the real burner will solve this problem. All the flame shapes were V and W, meaning an optimal condition for combustion chamber loading. Even though the overall mass flow rates at the inlet are increasing with the decreasing heating value of the fuel, natural gas combustion showed the highest velocity and temperature in the flow field. Overall, a small hydrogen dilution of the CH 4-CO2 containing fuel acted as an excellent combustion stabilizer without flashback or too intense heat release rate. As a consequence, the presently analyzed burner can run on low calorific value fuels without design modifications or exposing locally high thermal load on the combustion chamber. Since it is an initial study, validation and the evaluation of practical relevance will be discussed in subsequent works.

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“…Detailed measurements of temperature, species and velocities in canonical, nonpremixed flames using various diagnostic techniques have provided valuable datasets for validation of turbulence-chemistry interaction models employed in large eddy simulations (LES). Swirl stabilized flames, relevant to gas turbine applications, present a challenging test case for LES models because of the complex coupling between velocity flow field, mixing field, and heat release [3,4]. Although several experimental datasets are available for open-jet swirl stabilized flames [5][6][7], data collected inside a conical quarl are rare because of the elevated technical difficulty of such measurements.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of quarl in increasing the blow-out limit of swirl stabilized non-premixed flames have been investigated in recent years [4]. Elbaz et al conducted temperature measurements using a fine-wire thermocouple as well as qualitative OH-PLIF measurements, but no quantitative species measurements inside the quarl are available [3,11]. Given the importance of mixing in non-premixed flames, experimental measurements of species mole fractions inside the conical quarl are highly desirable.…”

Section: Introductionmentioning

confidence: 99%

Mole fraction measurement through a transparent quarl burner using filtered Rayleigh scattering

et al. 2019

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A filtered Rayleigh scattering system is developed and applied to measure the mole fraction of methane in a methane-air swirl flow through a transparent conical quartz quarl. Light scattering from the location where the laser beam is incident on the surface of the quarl is orders of magnitudes larger than Rayleigh scattering from the gas mixture of interest. This diffusive scattering is suppressed using molecular absorption by an iodine cell and using spatial filtering by an optical aperture. Residual stray light accounted for up to 5% of the total signal and had to be removed for accurate measurements. The flow consisted of a non-premixed mixture of methane and air in the central jet surrounded by a strong swirling air flow. Measurements were conducted at a height of 4 mm from the fuel tube's exit for six different conditions of the swirl flow to demonstrate the ability of the instrument to study the effects of swirl strength and fuel flow rate on the mixing process. By using a 4-leg pulse stretcher to allow higher laser energies in the probe volume, large collection optics and a reference iodine cell to monitor laser wavelength variations, standard deviations of ~ 0.006 in air and ~ 0.012 in a laminar methane flow were achieved for mole fraction measurements.

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Effect of burner geometry on swirl stabilized methane/air flames: A joint LES/OH-PLIF/PIV study

Cited by 33 publications

References 44 publications

An Experimental Investigation on the NO and CO Emission Characteristics of a Swirl Convergent-divergent Nozzle at Elevated Pressure

An Experimental Investigation on the NO and CO Emission Characteristics of a Swirl Convergent-divergent Nozzle at Elevated Pressure

Numerical analysis of biogas combustion in a lean premixed swirl burner

Mole fraction measurement through a transparent quarl burner using filtered Rayleigh scattering

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