The structure of turbulent flames in fractal- and regular-grid-generated turbulence

Sponfeldner, Thomas; Soulopoulos, N.; Beyrau, Frank; Hardalupas, Y.; Taylor, A. M. K. P.; Vassilicos, J. C.

doi:10.1016/j.combustflame.2015.06.004

Cited by 32 publications

(44 citation statements)

References 79 publications

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“…Turbulent premixed combustion modeling is essential for various applications, such as gas turbine, spark-ignition engine, and furnace operations, because it helps in improving these technologies to reduce emissions and increase power efficiency. The effects of the turbulent flow field properties of flames are significant because they extremely increase the flame propagation velocity (turbulent flame speed, U t ) [1]. Turbulence can be generated by using an active regular or fractal grid that is placed on the upstream flame region to develop a velocity field [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Active-grid turbulence effect on the topology and the flame location of a lean premixed combustion

Alhumairi

Ertunç

2018

THERM SCI

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Lean premixed combustion under the influence of active-grid turbulence was computationally investigated, and the results were compared with experimental data. The experiments were carried out to generate a premixed flame at a thermal load of 9 kW from a single jet flow combustor. Turbulent combustion models, such as the coherent flame model and turbulent flame speed closure model were implemented for the simulations performed under different turbulent flow conditions, which were specified by the Reynolds number based on Taylor's microscale, the dissipation rate of turbulence, and turbulent kinetic energy. This study shows that the applied turbulent combustion models differently predict the flame topology and location. However, similar to the experiments, simulations with both models revealed that the flame moves toward the inlet when turbulence becomes strong at the inlet, that is, when Re λ at the inlet increases. The results indicated that the flame topology and location in the coherent flame model were more sensitive to turbulence than those in the turbulent flame speed closure model. The flame location behavior on the jet flow combustor significantly changed with the increase of Re λ .

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Section: Introductionmentioning

confidence: 99%

Active-grid turbulence effect on the topology and the flame location of a lean premixed combustion

Alhumairi

Ertunç

2018

THERM SCI

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“…It is because, in the same percentage of blockage ratio, the maximum turbulence intensity of non-circular geometry is much higher than circular geometry. There have been several studies looking at the effect of blockage ratio [19]. Depending on blockage ratio Castro demonstrated experimentally that two well distinguishable flow regimes exist.…”

Section: Blockage Ratiomentioning

confidence: 99%

Circle grid fractal plate as a turbulent generator for premixed flame: an overview

Othman

Manshoor

Khalid

2013

IOP Conf. Ser.: Mater. Sci. Eng.

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“…Ahmadi-Baloutaki [18] found the turbulence downstream generated by the current grid to be quasi-isotropic in the wind tunnel and obtained the actual features of the problem but with the information unspecified in the entire turbulent field. Sponfeldner [19] used four space-filling fractal square grids and one regular square mesh grid to form high turbulence intensities for premixed V-shaped flames. The flames have larger turbulent burning velocity in the turbulence of fractal grid than in regular gridgenerated turbulence.…”

Section: State Of the Artmentioning

confidence: 99%

Numerical and Experimental Studies on Grid-Generated Turbulence in Wind Tunnel

Liu¹,

Zhang²,

Wu³

et al. 2017

JESTR

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The grid-generated turbulence in wind tunnel is commonly applied in aerodynamic performance experiments of various industrial structures. However, the characteristics and application conditions of the grid-generated turbulence in the wind tunnel are often affected by the grid shape and the test position, respectively. Therefore, in order to clarify the influence of the grid shape and the test position on the grid-generated turbulence in wind tunnel, a computational fluid dynamics (CFD) numerical study on the turbulence generated by two different grids was presented herein, with the wind tunnel experimental validation. Firstly, time histories of the wind speed at 19 monitoring points behind the grid in wind tunnel were collected. Secondly, the entire turbulent field generated by two different grids was simulated using CFD. Then, the characteristics of the turbulence generated by the grids in wind tunnel were investigated. Finally, the accuracy of the CFD simulations compared with the wind tunnel test was studied. Results show that the grid blockage and the interference effect lead to a significant increase of 200% in the turbulence intensity near the grid. Moreover, the grid-generated turbulence conforms to the isotropic assumption only after a specific distance of 2.0-4.0 m from the grid. In addition, CFD errors are generally within 15%-20% of the corresponding measurements in the wind tunnel. This study provides guidance for selecting the installation location of the structure model in a wind tunnel.

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The structure of turbulent flames in fractal- and regular-grid-generated turbulence

Cited by 32 publications

References 79 publications

Active-grid turbulence effect on the topology and the flame location of a lean premixed combustion

Active-grid turbulence effect on the topology and the flame location of a lean premixed combustion

Circle grid fractal plate as a turbulent generator for premixed flame: an overview

Numerical and Experimental Studies on Grid-Generated Turbulence in Wind Tunnel

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