On Some Recent Applications of the Coanda Effect to Acoustics

Lubert, Caroline P.

doi:10.1121/1.3694201

Cited by 7 publications

(7 citation statements)

References 17 publications

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“…When a jet of fluid is passed over a curved or a strongly divergent nozzle the jet is pulled onto the curved surface as a result of the low pressure region which develops as entrainment by the jet removes gases from the region between the jet and the surface. The balance between the inward radial pressure gradient and the outward centrifugal force then holds the jet to the wall [8]. The [7] substantial flow deflection offered by the Coanda principle is generally accompanied by enhanced levels of turbulence.…”

Section: Introductionmentioning

confidence: 99%

“…A related, although undesirable side effect is the significant increase in associated noise levels [8,12]. 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%

“…The [7] substantial flow deflection offered by the Coanda principle is generally accompanied by enhanced levels of turbulence. A related, although undesirable side effect is the significant increase in associated noise levels [8,12]. Applications of the phenomenon vary from aerospace design stealth technology to burners and medicine applications [8,13,14].…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…This section aims at highlighting a few of them and describing what the effect permits to achieve. This section is far from exhaustive, for a more in-depth review, the paper from Lubert [11] can be consulted.…”

Section: Applicationsmentioning

confidence: 99%

Assessment of CFD capability for prediction of the Coandă effect

Mauret

2021

Preprint

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“…The Coandă effect for ACB system is illustrated in Figure 2.2. This effect has become increasingly used in a wide variety of applications, including medical, industrial, aerodynamics, and maritime technology [39]. It is shown that this effect can increases the air throw by up to 40% [40].…”

Section: Air Distribution For Acb Systems 24mentioning

confidence: 99%

Air distribution and thermal comfort for active chilled beam systems

Wu¹

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During the past few decades, the active chilled beam (ACB) system has become increasingly prevalent worldwide as a promising air conditioning and mechanical ventilation (ACMV) system. It is acknowledged that ACB systems have the advantages of providing high energy efficiency, good thermal comfort, and satisfied noise control with a lower space requirement. In modern society, the thermal discomfort and excessive energy consumption are the two major concerns for ACMV systems. People, especially in developed countries, spend substantial of their time in air-conditioned rooms. The poor air quality and inferior thermal condition incur plenty of uncomfortable sensations and even give rise to sicknesses such as sick building syndrome. One of the most common and serious problems is sensation of draught, which is mainly caused by the unpleasant cooling of air movement. Therefore, it is significantly important to evaluate the air distribution and thermal comfort for ACB systems. However, the previous studies mainly focused on cooling capacity, energy-saving effect and mechanical optimization of ACB systems. The studies on air distribution and thermal comfort are still inadequate to provide a comprehensive perspective on ACB systems. In order to fulfil the gaps, the airflow pattern is experimentally and numerically studied for ACB systems. Through experiments, an un-uniform air distribution is found near the nozzles in ACB terminals and this found distribution has a great chance to cause uncomfortable feeling such as draught in the occupied zone. A three-dimensional computational fluid dynamics (CFD) model for ACB terminal is built and validated by particular experiments. A proper strategy to balance the air distribution is proposed and validated by CFD simulation. Besides, the velocity contours near the ceilings are captured and the characteristics of Coandă effect, self-similarity, and turbulence intensity for air jet are discussed under various air supply temperatures and pressures. In addition, the effects of the heat sources' configuration and strength on thermal comfort are experimentally investigated in a mock-up room with ACB systems. The full-scale

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On Some Recent Applications of the Coanda Effect to Acoustics

Cited by 7 publications

References 17 publications

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

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

Assessment of CFD capability for prediction of the Coandă effect

Air distribution and thermal comfort for active chilled beam systems

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