Reduced basis simulations as a tool for generating turbulent inlet‐data for two opposing jets

Johansson, Peter S.; Andersson, Helge I.

doi:10.1002/fld.878

Cited by 2 publications

(3 citation statements)

References 13 publications

(19 reference statements)

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“…Such effect becomes highly pronounced as more opposing jets (shown later) are involved with a smaller separation distance, since the resulting pressure of impingement (dominating across a larger spherical zone) will approach the ports further. This is supported by the computations of Johansson and Andersson 6 who found that (for two opposing jets of 2 cm diameter and 20 cm separation distance) a separation bubble of 8 cm diameter develops in the stagnation region with a peak pressure of nearly 70 Pa. The subsequent influence of the stagnation pressure on the flow development near the ports in their work is currently reproduced in Figure 5(a) when the separation distance is decreased to 9 cm (with X = 45 mm from the port to the impact point where the pressure reaches a peak of 154 Pa).…”

Section: Resultssupporting

confidence: 57%

“…It is thus highlighted that multiple opposing jets are an effective mechanism to merge their respective powerful shearing zones in the vicinity of their ports. Johansson and Andersson 6 stated that the mean rate of the normal strain is important in such stagnating flows due to the highly adverse pressure gradient, whereby a considerable streamline curvature exists. They found that the consequent increase in the maximum turbulent energy from the jet inlet to the stagnation region is about 500%.…”

Section: Introductionmentioning

confidence: 99%

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Development of a multiple opposing jets’ burner for premixed flames

Kamal

2012

Proceedings of the Institution of Mechanical Engineers, Part A:

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A burner was developed to accommodate multiple opposing premixed flames, where the turbulence stimulated by impingement was found to extend the stability limits of methane/air mixtures. The opposing jets established closed loop flow currents in a number of sectors, which is twice that of the jets thus providing more eddies within a stronger turbulent flame structure. The stagnation zone for four opposing jets was testified to be larger than that for two jets such that it was able to sustain higher reactive jet velocities up to 14.2 m/s at larger flow shearing rates. Increasing the number of opposing jets and decreasing their separation distance provided higher rates of heat/mass transfer into the ports. As the flow deceleration zone was enlarged, the correspondingly higher burning capacities were correlated to the port diameter, the separation distance, the number of jets, Reynolds number, and the strain rate. Strain rates of growing magnitudes up to 13,080 s−1 were sustained at jet velocities as high as 21.8 m/s. At such velocities and upon increasing the ratio of the jet diameter to the separation distance, the turbulent kinetic energy was found to exhibit one local peak, as the strain rate due to impingement became enriched by the jet radial shearing effects. A lean blowout equivalence ratio of 0.59 was pronounced as a basis for acquiring low NOx emissions. The burner serves as a potential prototype for increasing the power-to-weight ratio of the combustion chambers like those utilized in furnaces, boilers, gas turbines, as well as jet-propelled vehicles with effectively minimized emissions of pollutants.

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Section: Resultssupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Development of a multiple opposing jets’ burner for premixed flames

Kamal

2012

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…2) as respectively resulting from the normal strain and the radial shearing. 31 On the other hand, a single zone (No. 4) develops on each shearing side of the cross-flow jet and gets additional strain effects from the vortical flow zone (No.…”

Section: Nox Emissions From the Multiple Pairs Of Opposing Jets' Burnermentioning

confidence: 99%

Combustion via multiple pairs of opposing premixed flames with a cross-flow

Kamal

2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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A cylindrical burner accommodating stoichiometric fuel-air mixture combustion via multiple pairs of opposing jets and a cross-flow provided heat intensification and duplication of the stagnation impact for extending the firing limits and maximizing the power density. Six pairs of circumferentially opposing stoichiometric mixture jets sustained bulk injection velocities as high as 21.8 m/s and were associated with NOx emissions of 22 ppm, while emissions of 10 ppm were recorded upon reaching a lean limit equivalence ratio of 0.59. A stoichiometric mixture jet issuing perpendicular to the opposing jets at a momentum flux ratio of 0.3 increased the turbulence production rates to the extent that increased the maximum bulk injection velocity to 28.3 m/s and reduced the NOx emissions to 17 ppm. Since the recirculation zones between the two stagnation centers got compressed by increasing the momentum flux ratio to 0.8, the corresponding residence time reduction decreased the NOx emissions to 12 ppm. As the cross-flow mixture was made fuel-lean, dilution of the stoichiometric mixture by the fuel-lean mixture combustion products made it possible to get NOx emissions of single digit ppm. Emissions of 9 ppm resulted from using the cross-flow fuel-lean mixture jet due to compromising the flame stability limit extension and the temperature reduction in the post flame region. Such emissions, in turn, decreased to 4 ppm as the momentum flux ratio increased to 1.7 at which the stoichiometric mixture flames shrank into their ports. A minimum NOx emission index of 0.27 g/kg fuel was thus obtained at a volumetric heat release of 50.4 MW/m 3. The momentum flux ratio corresponding to merging the two stagnation zones was correlated with Reynolds and Froude numbers, the jets' separation as well as the density and viscosity values pertaining to the lean and stoichiometric mixtures' flame temperatures.

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Reduced basis simulations as a tool for generating turbulent inlet‐data for two opposing jets

Cited by 2 publications

References 13 publications

Development of a multiple opposing jets’ burner for premixed flames

Development of a multiple opposing jets’ burner for premixed flames

Combustion via multiple pairs of opposing premixed flames with a cross-flow

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