Application of Turbulent Mixing Noise Theory to Flows over Coanda Surfaces

Lubert, Caroline P.

doi:10.20855/ijav.2008.13.1221

Cited by 4 publications

(4 citation statements)

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“…Applications of the phenomenon vary from aerospace design stealth technology to burners and medicine applications [8,13,14]. However, the complex nature of the flow in 3 dimensions is still a challenge and many of its effects are still barely understood [15].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics During the Transient Evolution of Open Jet Flows from/to Wall Attached Jets

Valera‐Medina

Baej

2016

Flow Turbulence Combust

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Swirl stabilized flows are the most widely deployed technology used to stabilize gas turbine combustion systems. However, there are some coherent structures that appear in these flows close to the nozzle whose occurrence and stability are still poorly understood during transition. The external recirculation zone and the Precessing Vortex Core to/from the Coanda effect are some of them. Thus, in this paper the transition of an Open Jet FlowMedium Swirl flow pattern to/from a Coanda jet flow is studied using various geometries at a fixed Swirl number. Phase Locked Stereo Particle Image Velocimetry and High Speed Photography experiments were conducted to determine fundamental characteristics of the phenomenon. It was observed that the coherent structures in the field experience a complete annihilation during transition, with no dependency between the structures formed in each of the flow states. Moreover, transition occurs at a particular normalized step size whilst some acoustic shifts in the frequencies of the system were noticed, a phenomenon related to the strength of the vortical structures and vortices convection. It is concluded that a transient, precessing, Coanda Vortex Breakdown is formed, changing flow dynamics. The structure progresses to a less coherent Trapped Vortex between the two states. During the phenomenon there are different interactions between structures such as the Central Recirculation Zone, the High Momentum Flow Region and the Precessing Vortex Core that were also documented.

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Section: Introductionmentioning

confidence: 99%

Hydrodynamics During the Transient Evolution of Open Jet Flows from/to Wall Attached Jets

Valera‐Medina

Baej

2016

Flow Turbulence Combust

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“…A direct consequence of these effects is often a significant escalation in the associated noise levels, and it is posited that this disadvantage has prevented its application from becoming more widespread in recent years. 4 Clearly, bet-ter understanding of the noise emission characteristics of turbulent Coanda jets will facilitate improvements in prediction and attenuation of such noise.…”

Section: The Coanda Effectmentioning

confidence: 99%

An Investigation of Initial Shock Cell Formation in Turbulent Coanda Wall Jets

Lubert¹,

Schwantes²,

Shafer³

2016

IJAV

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“…In an alternative approach in which the aim is to understand and alter the fundamental high-frequency noise generating mechanisms associated with Coanda flows, namely Turbulent Mixing Noise (TMN) and Shock-Associated noise (SAN), a theory was developed [50][51] for predicting the TMN emitted by unit volume of jet-type shear-layer turbulence close to a rigid plane, and extended to a plane two-dimensional wall-jet. Since most flows of practical interest are three-dimensional, and often the surface is curved, this model was further extended [52][53] to predict the aeroacoustic characteristics of a three-dimensional turbulent flow over a particular Coanda surface. Comparisons with experimental data were good, and the theory is currently being generalized to more commonly-occurring Coanda surfaces.…”

Section: Figure 8: An Operating Coanda Flarementioning

confidence: 99%