Subsonic and supersonic combustion using noncircular injectors

Gutmark, E.; Schadow, K. C.; Wilson, Kenneth

doi:10.2514/3.23317

Cited by 69 publications

(32 citation statements)

References 12 publications

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“…The higher turbulence intensities at the corners of the triangular and rectangular nozzles have been shown by [19] to produce a stronger vortex pair which enhances entrainment and spreading rates. There are different scales of turbulence for the asymmetric nozzles according to [12]. The small-scale structures occur at the nozzle corners and the large-scale structures at the flat sides [12].…”

Section: Development Of the Jet Half-velocity Width With The Presencementioning

confidence: 99%

“…Furthermore, Zaman [20], and Gutmark and co-workers [7][8][9] reported discrepancies concerning the extent of the increase in jet spreading and entrainment of rectangular nozzles as opposed to circular nozzles. Indeed, while Gutmark and co-workers [10][11][12] observed considerable increase in jet spreading and entrainment of the rectangular nozzles (with an aspect ratio of 2:1) compared to their circular nozzle counterpart, Zaman [20], who performed an experiment at a much higher Reynolds number (i.e. compressible flow) observed only slight increase for the same geometry.…”

mentioning

confidence: 90%

“…For example, it was reported that asymmetric nozzles (especially the triangular, rectangular, and elliptical nozzles) promote higher entrainment and jet spreading compared to their circular (axisymmetric) counterparts (e.g., [10][11][12][13][14][15][16][17][18][19]). Among the studies on asymmetric nozzles (e.g., [10][11][12][13][14][15][16][17][18][19]), it is reported, for instance, that the triangular nozzle's jet has a higher entrainment rate than the rectangular jet. However, there are still discrepancies between the results reported in different published studies.…”

mentioning

confidence: 99%

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Effect of Sudden Expansion on Entrainment and Spreading Rates of a Jet Issuing from Asymmetric Nozzles

Iyogun

Birouk

2008

Flow Turbulence Combust

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Turbulent free jets issuing from five different nozzle geometries; smooth pipe, contracted circular, rectangular, triangular, and square, are experimentally investigated by using TSI 2-D laser Doppler velocimetry (LDV) to assess the effect of nozzle geometry and quarl (i.e. a cylindrical sudden expansion) on jet entrainment and spreading. The centerline mean velocity decay and the jet half-velocity width, which are indicators of jet entrainment and spreading rates, are determined for each nozzle's flow configuration, i.e. with and without sudden expansion. Furthermore, turbulence quantities, such as the flow mean velocities and their mean fluctuating components, as well as Reynolds shear stresses, are all measured along the centerline plane of the jet to facilitate understanding the extent of the effect of nozzle's geometry (i.e. nozzle's orifice shape and sudden expansion) on jet's entrainment and spreading. The main results show that the jet flow with the presence of sudden expansion exhibits higher rates of entrainment and spreading than without. In addition, these results reveal that sudden expansion exercises a greater effect on the asymmetric jet characteristics, especially for the triangular and rectangular nozzles compared to their axisymmetric counterparts (i.e. circular contracted nozzle).

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Section: Development Of the Jet Half-velocity Width With The Presencementioning

confidence: 99%

mentioning

confidence: 90%

mentioning

confidence: 99%

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Effect of Sudden Expansion on Entrainment and Spreading Rates of a Jet Issuing from Asymmetric Nozzles

Iyogun

Birouk

2008

Flow Turbulence Combust

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“…Gutmark et al [21,22] compared the mixing characteristics between the circular, elliptic and rectangular jets from the subsonic flow to supersonic flow, and found that the elliptic and rectangular jets had a higher spreading rate relative to the circular jet, especially at the minor axis plane. After that, there have been some efforts [23][24][25][26][27][28] devoted to directly comparing the flow properties between the underexpanded jets issuing from different nozzle geometries.…”

Section: Introductionmentioning

confidence: 99%

Flow characteristic of highly underexpanded jets from various nozzle geometries

Zhou

Yao

et al. 2017

Applied Thermal Engineering

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“…In partially nonpremixed flames, except in the near-burner region, the local air-fuel ratio depends upon the air-infusion rate into the burning jet, which can be controlled either by changing the flow dynamics or manipulating the downstream flow characteristics of the gas jet. The application of non-axisymmetric burner exit geometries (Gollahalli et al, 1992;Gutmark et al,1991;Schadow et al, 1989;Kamal and Gollahalli, 1993;Papanikolau and Wierzba, 1996;Papanikolau et al, 1997) is an example of such a technique that showed some improvements in the combustion and emission characteristics of burning gas jets.…”

Section: Introductionmentioning

confidence: 99%

Control of Pollutant Emissions in Natural Gas Diffusion Flames by Using Cascade Burners

Qubbaj¹

2001

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The goal of this exploratory research project is to control the pollutant emissions of diffusion flames by modifying the air infusion rate into the flame. The modification was achieved by installing a cascade of venturis around the burning gas jet. The basic idea behind this technique is controlling the stoichiometry of the flame through changing the flow dynamics and rates of mixing in the combustion zone with a set of venturis surrounding the flame. A natural gas jet diffusion flame at burner-exit Reynolds number of 5100 was examined with a set of venturis of specific sizes and spacing arrangement.The thermal and composition fields of the baseline and venturi-cascaded flames were numerically simulated using CFD-ACE+, an advanced computational environment software package. The instantaneous chemistry model was used as the reaction model.The concentration of NO was determined through CFD-POST, a post processing utility program for CFD-ACE+. The numerical results showed that, in the near-burner, midflame and far-burner regions, the venturi-cascaded flame had lower temperature by an average of 13%, 19% and 17%, respectively, and lower CO 2 concentration by 35%, 37%and 32%, respectively, than the baseline flame. An opposite trend was noticed for O 2 concentration; the cascaded flame has higher O 2 concentration by 7%, 26% and 44%, in average values, in the near-burner, mid-flame and far-burner regions, respectively, than in the baseline case. The results also showed that, in the near-burner, mid-flame, and farburner regions, the venturi-cascaded flame has lower NO concentrations by 89%, 70%and 70%, in average values, respectively, compared to the baseline case.The numerical results substantiate that venturi-cascading is a feasible method for controlling the pollutant emissions of a burning gas jet. In addition, the numerical results were useful to understand the thermo-chemical processes involved. The results showed that the prompt-NO mechanism plays an important role besides the conventional thermal-NO mechanism. The computational results of the present study need to be validated experimentally 4

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Subsonic and supersonic combustion using noncircular injectors

Cited by 69 publications

References 12 publications

Effect of Sudden Expansion on Entrainment and Spreading Rates of a Jet Issuing from Asymmetric Nozzles

Effect of Sudden Expansion on Entrainment and Spreading Rates of a Jet Issuing from Asymmetric Nozzles

Flow characteristic of highly underexpanded jets from various nozzle geometries

Control of Pollutant Emissions in Natural Gas Diffusion Flames by Using Cascade Burners

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