Thermal pollution level reduction by sweeping jet-based enhanced heat dissipation: A numerical study with calibrated Generalized k-ω (GEKO) model

Li, Ziyan; Liu, Yudan; Zhou, Wenwu; Wen, Xin; Liu, Yingzheng

doi:10.1016/j.applthermaleng.2021.117990

Cited by 15 publications

(5 citation statements)

References 124 publications

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“…8). Similar entrainment characteristics of a spatially oscillating jet ejecting into a non-con ned quiescent environment have been discussed in Li et al (2021) and Ostermann et al (2018). In the current study, the extremely con ned geometry increased the friction between the jet and wall surface and thus increased the energy consumption, such that all dissipations were expected to be larger than those occurring in open space.…”

Section: At Phase Anglesupporting

confidence: 77%

“…More and more studies focused on the ow characteristics of uidic oscillators under extreme conditions or at microscales. For example, Shabnam et al (2022) experimentally investigated the ow characteristics of an oscillating jet emitted by a uidic oscillator at a high nozzle-pressure ratio (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Park et al (2020) used the design of experiment method analyzed the statistical information of a two-feedback channel oscillator con guration under supersonic conditions.…”

Section: Introductionmentioning

confidence: 99%

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Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Song,

Wang,

Qiu

et al. 2024

Exp Fluids

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The present study optimized some novel uidic oscillator designs, measured their internal-external uid dynamics, and used modal analysis to reveal their underlying oscillation mechanisms. It also investigated the effects of structural parameters on their uid dynamics. The time-resolved internalexternal pressure elds of the oscillators were determined by using pressure-sensitive paint (PSP) measurement. Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) were used for modal analysis and phase reconstruction. The time-averaged pressure-eld and phasereconstruction results reveal that recirculation bubbles inside the mixing chamber and the feedback ow have underpinned the mechanism of formation of internal and external continuous sweeping ows. The modal analysis results reveal the spatial modal structures and their time evolution, which dominated the internal-external ow pattern. The inlet-wedge width and feedback-channel inlet diameter were found to be the structural parameters affecting feedback ow and recirculation-bubble size, and thereby in uenced ow characteristics such as jet oscillation frequency and divergence angle. Different Coandă surfaces altered the recirculation bubbles and feedback ow of the mainstream, thereby in uencing the formation mechanism of the sweeping jet.

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Section: At Phase Anglesupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Song,

Wang,

Qiu

et al. 2024

Exp Fluids

Self Cite

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“…Consequently, a new Generalized k-ω (GEKO) adjustable model was recently proposed by ANSYS Inc. (Canonsburg, PA, USA) to cover a wide range of flow scenarios by providing several freely adjustable parameters. Similarly, changing these physical parameters does not affect the thermal and dynamic behavior of the air flow [33]. Publications on the details of the GEKO model are rather limited [34,35].…”

Section: Numerical Set-upmentioning

confidence: 99%

Analysis of the Thermo-Aeraulic Behavior of a Heated Supply Air Window in Forced Convection: Numerical and Experimental Approaches

2023

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This paper presents work intended to characterize air flow and convective heat transfers within a ventilated window. This window is a device that allows for the entry of fresh air into a building while simultaneously preheating it in order to satisfy requirements in terms of air quality and thermal comfort in inhabited spaces. Therefore, this essential component of the building envelope functions herein as a heat exchanger with its own geometric characteristics and exchange conditions. In this research, a dual numerical and experimental approach has been implemented in order to highlight the temperatures, velocities and heat flux fields both at the glazing surfaces and in the ventilated air gaps. Several turbulence models were tested using CFD software (ANSYS-FLUENT®); their results were compared with each other as well as with the experimental results. This study shows that the air gap geometry in the window induces flow disturbances, recirculation phenomena and non-uniform heat exchanges, all of which prove to be important in terms of overall component performance. With regard to modeling and, in particular, at the level of turbulence models, the results obtained indicate that the model GEKO is best suited to the configuration under study when the phenomena of turbulent forced convection dominate the dynamics of the transfers. The k-ε models reveal a tremendous weakness in precisely estimating the problem’s characteristic quantities. From an experimental point of view, local measurements of thermal fluxes and temperatures demonstrate high efficiency with regard to experimental technique, which in turn could be extended to many different configurations for the local evaluation of convection heat transfer.

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“…The link between the output frequency and the feedback channel dimensional modifications was explored. CFD simulations using the k-omega (GECO) turbulence model with the aim of understanding thermal pollution in water jets was studied in [32]; they observed that the use of sweeping jet oscillators created a thermal dilution effect, drastically reducing the thermal pollution. The jet structures generated and their associated decay patterns were obtained.…”

Section: Introductionmentioning

confidence: 99%

Analysis of a Novel Fluidic Oscillator under Several Dimensional Modifications

Karimzadegan,

Mirzaei,

Bergada

2024

Applied Sciences

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To activate the boundary layer in Active Flow Control (AFC) applications, the use of pulsating flow has notable energy advantages over constant blowing/suction jet injections. For a given AFC application, five parameters, jet location and width, inclination angle, frequency of injection, and the momentum coefficient, need to be tuned. Presently, two main devices are capable of injecting pulsating flow with a momentum coefficient sufficient to delay the boundary layer separation: these are zero-net-mass-flow Actuators (ZNMFAs) and fluidic oscillators (FOs). In the present study, a novel FO configuration is analyzed for the first time at relatively high Reynolds numbers, and fluid is considered to be incompressible. After obtaining the typical linear correlation between the incoming Reynolds number and the outlet flow oscillating frequency, the effects of dimensional modifications on outlet width and mixing chamber wedge inclination angle are addressed. Modifications of the outlet width were observed to create large variations in FO performance. The origin of self-sustained oscillations is also analyzed in the present manuscript and greatly helps in clarifying the forces acting on the jet inside the mixing chamber. In fact, we can conclude by saying that the current FO configuration is pressure-driven, although the mass flow forces appear to be much more relevant than in previously studied FO configurations.

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Thermal pollution level reduction by sweeping jet-based enhanced heat dissipation: A numerical study with calibrated Generalized k-ω (GEKO) model

Cited by 15 publications

References 124 publications

Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Analysis of the Thermo-Aeraulic Behavior of a Heated Supply Air Window in Forced Convection: Numerical and Experimental Approaches

Analysis of a Novel Fluidic Oscillator under Several Dimensional Modifications

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