The Influence of Fuel Jet Precession on the Global Properties and Emissions of Unconfined Turbulent Flames

Nathan, Graham J.; Turns, Stephen R.; Bandaru, Ramarao V.

doi:10.1080/00102209608951958

Cited by 27 publications

(17 citation statements)

References 12 publications

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“…These studies, along with Schneider et al (1997b) also reveal that St p has a much greater influence on the flow than does the Reynolds number (Re d = ud/ν), where ν is the kinematic viscosity of air. These findings are further supported by the investigation of Nathan, Turns & Bandaru (1996) of the effect of precession on flames from the same nozzle.…”

Section: Introductionsupporting

confidence: 69%

The naturally oscillating flow emerging from a fluidic precessing jet nozzle

2008

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Phase-averaged and directionally triggered digital particle image velocimetry measurements were taken in longitudinal and transverse planes in the near field of the flow emerging from a fluidic precessing jet nozzle. Measurements were performed at nozzle inlet Reynolds and Strouhal numbers of 59 000 and 0.0017, respectively. Results indicate that the jet emerging from the nozzle departs with an azimuthal component in a direction opposite to that of the jet precession. In addition, the structure of the 'flow convergence' region, reported in an earlier study, is better resolved here. At least three unique vortex-pair regions containing smaller vortical 'blobs' are identified for the first time. These include a vortex-pair region originating from the foci on the downstream face of the nozzle centrebody, a vortex-pair region shed from the edge of the centrebody and a vortex-pair region originating from the downstream surface of the nozzle exit lip.

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Section: Introductionsupporting

confidence: 69%

The naturally oscillating flow emerging from a fluidic precessing jet nozzle

2008

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“…In comparison, the influence of Re is negligible. Similarly, Nathan et al (1996) find that St p has a dominant influence on the characteristics of a MPJ flame. These observations for the MPJ are also valid for the self-excited PJ cases (Mi and Nathan, 2004).…”

Section: Discussionmentioning

confidence: 93%

The influence of inlet flow condition on the frequency of self-excited jet precession

Nathan

Wong

2006

Journal of Fluids and Structures

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“…Nathan et al 25 investigated the effect of varying the Strouhal number of precession, St p = f p d / U e (where f p , d and U e denote the precession frequency, exit diameter, and mean velocity of the jet, respectively) on the global performance of open jet flames of methane and propane. They found that, by changing St p with all other parameters held constant it is possible to produce a wide range of different flame types from yellow to blue.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of the velocity field in a mechanical precessing jet flow

Nathan

2004

Physics of Fluids

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An experimental investigation of a precessing jet issuing from a mechanically rotating nozzle directed at an angle of ␣ = 45°relative to the axis of rotation is reported. Both conventional and conditional statistics of the velocity field of the jet were measured using a combined hot-wire and cold-wire (to identify any reverse flow) probe. Three distinct values (Ϸ0.005, 0.01, and 0.02) of the precession Strouhal number St p (ϵ rotation frequency ϫ nozzle diameter / jet exit bulk velocity) were used to assess the effect of varying St p . The measurements reveal that the Strouhal number in general has significant influence on the entire mixing field generated by a precessing jet. The occurrence of precession at all the Strouhal numbers of investigation produces a central recirculation zone at x ഛ 7d, where x is a distance measured from the rotating nozzle exit. A critical Strouhal number, i.e., St p,cr Ϸ 0.008 for the present case, is identified: at St p ജ St p,cr the core jet converges to the axis of rotation while at St p ജ St p,cr it does not. The characteristics of the turbulent flow in the near and intermediate regions are quite different and depend upon the magnitude of St p . The near-field region, x / d ഛ 10-15, is dominated by a regime of global precession of the entire jet. As a result, the large-scale entrainment of the ambient fluid is substantially enhanced while the fine-scale turbulent mixing is suppressed. Under the supercritical regime (i.e., St p ജ St p,cr ), the jet in the far field resembles some features of the nonprecessing counterpart. Nevertheless, significant differences still retain in the statistical properties.

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The Influence of Fuel Jet Precession on the Global Properties and Emissions of Unconfined Turbulent Flames

Cited by 27 publications

References 12 publications

The naturally oscillating flow emerging from a fluidic precessing jet nozzle

The naturally oscillating flow emerging from a fluidic precessing jet nozzle

The influence of inlet flow condition on the frequency of self-excited jet precession

Statistical analysis of the velocity field in a mechanical precessing jet flow

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