Turbulent diffusion flame properties behind a backward-facing step

Wu, Meng; Walterick, R. E.; Groot, W. A. De; Jagoda, Jechiel I.; Strahle, Warren C.

doi:10.2514/3.23577

Cited by 5 publications

(3 citation statements)

References 7 publications

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“…2-3b). The shift in the reattachment location has been observed previously with inert mass injection [23] and heat release [35]. The large-scale BrownRoshko vortices [5] are visible in the inert shear-layer (Fig.…”

Section: Flowfield For Inert and Reacting Injectionmentioning

confidence: 60%

“…Increased injection will push reattachment downstream, increasing the length of the recirculation zone and changing the pressure coefficient at a given downstream location [23]. Reattachment location and pressure coefficient can also be controlled by varying the amount of heat release via exothermic chemical reactions [10,35]. The volumetric entrainment of free-stream fluids into shear layers is known to decrease with heat release [10,36], thus providing a trade between increased heat release and increased mass injection.…”

Section: Flowfield For Inert and Reacting Injectionmentioning

confidence: 97%

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Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part I: Subsonic Flow

Bergthorson

Johnson

Bonanos

et al. 2009

Flow Turbulence Combust

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The mixing and flowfield of a complex geometry, similar to a rearwardfacing step flow but with injection, is studied. A subsonic top-stream is expanded over a perforated ramp at an angle of 30 • , through which a secondary stream is injected. The mass flux of the second stream is chosen to be insufficient to provide the entrainment requirements of the shear layer, which, as a consequence, attaches to the lower guidewall. Part of the flow is directed upstream forming a re-entrant jet within the recirculation zone that enhances mixing and flameholding. A control-volume model of the flow is found to be in good agreement with the variation of the overall pressure coefficient of the device with variable mass injection. The flowfield response to changing levels of heat release is also quantified. While increased heat release acts somewhat analogously to increased mass injection, fundamental differences in the flow behaviour are observed. The hypergolic hydrogen-fluorine chemical reaction employed allows the level of molecular mixing in the flow to be inferred. The amount of mixing is found to be higher in the expansion-ramp geometry than in classical freeshear layers. As in free-shear layers, the level of mixing is found to decrease with increasing top-stream velocity. Results for a similar configuration with supersonic flow in the top stream are reported in Part II of this two-part series.

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Section: Flowfield For Inert and Reacting Injectionmentioning

confidence: 60%

Section: Flowfield For Inert and Reacting Injectionmentioning

confidence: 97%

Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part I: Subsonic Flow

Bergthorson

Johnson

Bonanos

et al. 2009

Flow Turbulence Combust

View full text Add to dashboard Cite

show abstract

“…Heat release reduces the shear layer's growth rate and entrainment requirements [8]. The resulting dilatation affects the flow by increasing the effective pressure on the lower-stream side, causing the initial shearlayer expansion angle to decrease, also pushing reattachment further downstream in the process [32]. Both of these effects act to increase the pressure coefficient.…”

Section: Flowfield Effects With Reacting Mass Injectionmentioning

confidence: 97%

Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part II: Supersonic Flow

Bonanos

Bergthorson

Dimotakis

2009

Flow Turbulence Combust

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Fundamental aspects of mixing between two gaseous streams in a complex geometry are studied and discussed. In the present paper, a supersonic top-stream is expanded over a 30 • ramp, through which a secondary lower-stream is injected. The mass flux through the secondary stream is purposely insufficient to provide the entrainment requirements of the resulting shear layer, causing it to attach to the lower guidewall. Part of the shear layer fluid is directed upstream forming a recirculation zone, with enhanced mixing characteristics. The pressure coefficient of the device is quantified as a function of velocity ratio. The effect of heat release on the pressure coefficient is also reported. Molecular mixing was measured employing "flip" experiments based on the hypergolic hydrogen-fluorine chemical reaction. The amount of mixing for the expansion-ramp geometry is found to be higher than in classical free shear layers. However, as in free shear layers, the level of mixing decreases with increasing top-stream velocity. Results for a similar configuration with subsonic/transonic flow in the top stream are reported in Part I of this two-part series.

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Ramjet Propulsion for Projectiles-an Overview of Worldwide Achievements and Future Opportunities

Veraar

Oosthuisen²,

Andersson³

2022

Int J Energetic Materials Chem Prop

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Turbulent diffusion flame properties behind a backward-facing step

Cited by 5 publications

References 7 publications

Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part I: Subsonic Flow

Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part I: Subsonic Flow

Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part II: Supersonic Flow

Ramjet Propulsion for Projectiles-an Overview of Worldwide Achievements and Future Opportunities

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