Assessment of Cooling Enhancement of Synthetic Jet in Conjunction With Forced Convection

2007 ◽  
Author(s):  
Yogen Utturkar ◽  
Mehmet Arik ◽  
Mustafa Gursoy
Keyword(s):  
Forced Convection ◽  
Cross Flow ◽  
Electronics Cooling ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Channel Height ◽  
Large Area ◽  
Complete Replacement ◽  
Cooling Enhancement ◽  
The Impact

Synthetic jets are meso or micro fluidic devices, which operate on the “zero-net-mass-flux” principle. They impart a positive net momentum flux to the external environment, and are able to produce the cooling effect of a fan sans its ducting, reliability issues, and oversized dimensions. As a result, recently their application as electronics cooling devices is gaining momentum. Traditionally, synthetic jets have been sought as a replacement to the fan in many electronic devices. However, in certain large applications, complete replacement of the fan is not feasible, because it is necessary to provide the basic level of cooling over a large area of a printed assembly board. Such applications often pose a question whether synthetic jet would be able to locally provide reasonable enhancement over the forced convection of the fan flow. In the present study, we present the cooling performance of synthetic jets complementing forced convection from a fan. Both experiments and CFD computations are performed to investigate the interaction of the jet flowfield with a cross flow from fan. The inlet velocity, jet disk amplitude, and channel height are varied in the computational simulations to evaluate the impact of these changes on the cooling properties. Overall, both studies show that a synthetic jet is able to pulse and disrupt the boundary layer caused from fan flow, and improve heat transfer up to 4× over forced convection.

High Fidelity and Compact Models of Synthetic Jets and Their Application in Aerodynamics and Microelectronics

1999 ◽  
Author(s):  
Andrzej J. Przekwas ◽  
Zhijian Chen ◽  
Marek Turowski
Keyword(s):  
Computational Simulation ◽  
Electronics Cooling ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Compact Model ◽  
High Fidelity ◽  
Computational Evaluation ◽  
Single Jet ◽  
Compact Models ◽  
Unsteady Fluid

Abstract Computational simulation of coupled unsteady fluid mechanics and electromechanical actuation of a single synthetic jet can be performed with available CFD tools. Modeling of flow physics of large arrays of synthetic jets is computationally very challenging. This paper presents two complementary computational technologies: a high-fidelity physical model of a single jet, and a reduced (compact) model of the jet for modeling large array of synthetic jets. The high-fidelity model first has been validated against experimental data and then used to calibrate the compact model. The paper presents computational evaluation of accuracy and range of applicability of compact models and demonstrates them on multi-dimensional simulations of aerodynamic flow control and on electronics cooling applications.

The performance of round synthetic jets in quiescent flow

2006 ◽  
Vol 110 (1108) ◽  
pp. 385-393 ◽  
Author(s):  
M. Jabbal ◽  
J. Wu ◽  
S. Zhong
Keyword(s):  
Near Field ◽  
Jet Flow ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Operating Conditions ◽  
Stroke Length ◽  
Synthetic Jet Actuators ◽  
Macro Scale ◽  
Jet Actuators ◽  
The Impact

AbstractPIV measurements in the near-field region of a jet flow emanating from a round synthetic jet actuator into quiescent air were conducted over a range of operating conditions. The primary purpose of this work was to investigate the nature of synthetic jets at different operating conditions and to examine the jet flow parameters that dictate the behaviour of synthetic jet actuators. The effects of varying diaphragm displacement and oscillatory frequency for fixed actuator geometry were studied. It was observed that the characteristics of synthetic jets are largely determined by the Reynolds number and stroke length. An increase in the former is observed to increase the strength of consecutive vortex rings that compose a synthetic jet, whereas an increase in the latter results in an increase in relative vortex ring spacing and for further increases in stroke length, shedding of secondary vortices. Correlations were also made between the operating parameters and the performance parameters most effective for flow control and which therefore determine the impact of a synthetic jet on an external flow. Relations of time-averaged dimensionless mass flux, momentum flux and circulation with the jet flow conditions were established and found to widely support an analytical performance prediction model described in this paper. It is anticipated that the experimental data obtained in this study will also contribute towards providing a PIV database for macro-scale synthetic jet actuators.

Flow Field and Heat Transfer of an Impinging Synthetic Jet in the Presence of Cross-Flow: Application of SAS and DES Approaches

2021 ◽  
pp. 095440892110644
Author(s):  
Farzad Bazdidi–Tehrani ◽  
Ali Saadniya ◽  
Soroush Rashidzadeh
Keyword(s):  
Heat Transfer ◽  
Flow Velocity ◽  
Active Flow Control ◽  
Experimental Studies ◽  
Cross Flow ◽  
Numerical Data ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Detached Eddy Simulation ◽  
Cross Flow Velocity

Nowadays, synthetic jets have various applications such as cooling enhancement and active flow control. In the present paper, the capability of two turbulence modelling approaches in predicting thermal performance of an impinging synthetic jet is investigated. These two approaches are scale adaptive simulation (SAS) and detached eddy simulation (DES). Comparisons between numerical data and experimental studies reveal that the ability of DES in predicting the asymmetrical trend of heat transfer profiles is better than SAS in almost all the study cases. Although, near the stagnation zone, the performance of SAS is superior. Results show that the effects of parameters such as frequency, cross-flow velocity and suction duty cycle factor are well predicted by both approaches. An increase of cross-flow velocity from 1.81 m/s to 2.26 m/s results in an improvement of [Formula: see text] near the stagnation point by almost 16.3% and 9.2% using DES and SAS, respectively.

An Experimental and Computational Sensitivity Analysis of Synthetic Jet Cooling Performance

2006 ◽  
Author(s):  
Yogen Utturkar ◽  
Mehmet Arik ◽  
Mustafa Gursoy
Keyword(s):  
Numerical Models ◽  
Heated Surface ◽  
Cross Flow ◽  
Heat Removal ◽  
Jet Impingement ◽  
Synthetic Jet ◽  
Thermal Source ◽  
Cooling Performance ◽  
Jet Cooling ◽  
The Impact

Synthetic jets are meso or micro scale fluidic devices, which operate on the "zero-net-mass-flux" principle. However, they impart a positive net momentum flux to the external environment, and are able to produce the cooling effect of a fan sans its ducting, reliability issues, and oversized dimensions. The rate of heat removal from the thermal source is expected to depend on the location, orientation, strength, and shape of the jet. In the current study, we investigate the impact of jet location and orientation on the cooling performance via time-dependent numerical simulations, and verify the same with experimental results. We firstly present the experimental study along with the findings. Secondly, we present the numerical models/results, which are compared with the experiments to gain the confidence in the computational methodology. Finally, a sensitivity evaluation has been performed by altering the position and alignment of the jet with respect to the heated surface. Two prime orientations of the jet have been considered, namely, perpendicular and cross jet impingement on the heater. It is found that if jet is placed at an optimum location in either impingement or cross flow position, it can provide similar enhancement.

An Experimental Study of a Synthetic Jet in Cross Flow in a Microchannel

2010 ◽  
Author(s):  
Alexander Sinclair ◽  
John Reizes ◽  
Victoria Timchenko ◽  
Gary Rosengarten
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Cross Flow ◽  
Oscillatory Solution ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Square Duct ◽  
Transfer Rates ◽  
Mixing Performance ◽  
Jet In Cross Flow

Laminar flow limits the mixing performance and heat transfer rates that occurs within microdevices. Synthetic jets in the microscale could disrupt laminar flow and improve the performance of such devices. In this paper a synthetic microjet integrated in a microchannel was designed and fabricated using micromachining techniques. The channel flow was driven by a syringe pump at a rate of 1.39μL/s and the device was actuated using a piezoceramic disc at a frequency of 600Hz. Flow fields were measured phase locked to the actuation cycle using the MicroPIV technique in the mid plane of the jet. The resultant fields revealed a jet with a largest velocity of 2.3m/s. The average velocity during expulsion was estimated to be 0.73m/s using a comparison to the oscillatory solution to flow in a square duct. Measurements at different phases in the cycle revealed a jet strong enough to impinge on the opposing wall and the growth and decay of a pair of vortices formed at the edge of the orifice. It was also shown that the synthetic jet significantly altered the flow patterns showing promising signs for enhancing mixing and heat transfer in microchannels.

Interaction of Synthetic Jet Cooling Performance With Gravity and Buoyancy Driven Flows

2007 ◽  
Author(s):  
Mehmet Arik ◽  
Yogen Utturkar ◽  
Mustafa Gursoy
Keyword(s):  
Heat Transfer ◽  
Heat Dissipation ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Jet Cooling ◽  
Impingement Heat Transfer ◽  
Buoyancy Driven Flows ◽  
Experimental Findings ◽  
Meso Scale

Meso scale cooling devices have been of interest for low form factor, tight space, and high COP thermal management problems. A candidate meso scale device, known as synthetic jets, operates with micro fluidic principles and disturbs the boundary layer causing significant heat transfer over conventional free convective heat transfer in air. Previous papers have dealt with the impingement and cross flow, but did not study mixed convection for synthetic jet with natural convection. In the present study, we discuss the results of an experimental study to investigate the interplay between jet orientations with respect to gravity, elevated temperature conditions, and synthetic jet heat dissipation capacity. Experiments were performed by placing synthetic at different positions around a square, 25.4mm heated flat surface. The flow physics behind the experimental findings is discussed. It is found that impingement heat transfer outperformed more than 30% compared to other orientations. The jet showed about 15% sensitivity to angular orientations.

An Experimental and Computational Heat Transfer Study of Pulsating Jets

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Yogen Utturkar ◽  
Mehmet Arik ◽  
Charles E. Seeley ◽  
Mustafa Gursoy
Keyword(s):  
Numerical Models ◽  
Heated Surface ◽  
Cross Flow ◽  
Heat Removal ◽  
Jet Impingement ◽  
Synthetic Jets ◽  
Thermal Source ◽  
Zero Net Mass Flux ◽  
Pulsating Jets ◽  
The Impact

Synthetic jets are meso or microscale fluidic devices, which operate on the “zero-net-mass-flux” principle. However, they impart a positive net momentum flux to the external environment and are able to produce the cooling effect of a fan sans its ducting, reliability issues, and oversized dimensions. The rate of heat removal from the thermal source is expected to depend on the location, orientation, strength, and shape of the jet. In the current study, we investigate the impact of jet location and orientation on the cooling performance via time-dependent numerical simulations and verify the same with experimental results. We firstly present the experimental study along with the findings. Secondly, we present the numerical models/results, which are compared with the experiments to gain the confidence in the computational methodology. Finally, a sensitivity evaluation has been performed by altering the position and alignment of the jet with respect to the heated surface. Two prime orientations of the jet have been considered, namely, perpendicular and cross jet impingement on the heater. It is found that if jet is placed at an optimum location in either impingement or cross flow position, it can provide similar enhancements.

scholarly journals Comparing the Influence of Synthetic jets on Cooling the Angled Plates Versus Vertical and Horizontal Plates

2021 ◽  
Vol 5 (2) ◽  
pp. 23-35
Author(s):  
Miralireza Nabavi ◽  
Moharram Jafari
Keyword(s):  
Heat Transfer ◽  
Open Source Software ◽  
Flow Separation ◽  
Flight Control ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Weak Efficiency ◽  
Previous Decade ◽  
Jet Nozzle ◽  
The Impact

Synthetic jets besides being used in heat transfer, have also been used to control turbulence and flow separation. In the previous decade, research on the applications of a synthetic jet has indicated that by using these types of jets, flow separation can be reduced or even stopped altogether. In addition, these jets have been utilized in unmanned aerial vehicles (UAVs) (to control separation on airfoils) and flight control. In this study, the jet is located perpendicular to the flat plane with fixed heat flux and the effect of some geometric parameters including the ratio of the distance between the jet and the impact plane to the nozzle width, the ratio of the impact plane length to the jet nozzle width, the ratio of synthetic jet width to width of the nozzle, the ratio of the hole height to the nozzle width, the angle of the impact plate as well as the diaphragm characteristics such as amplitude and frequency of the jet diaphragm in heat transfer were evaluated numerically by using OpenFOAM open-source software. The findings indicate that synthetic jets have very weak efficiency for cooling vertical panels. However, they are extremely effective on angled plates. Synthetic jets have more influence on angled planes than horizontal planes.

scholarly journals Heat Transfer in Adjacent Interacting Impinging Synthetic Jets

2009 ◽  
Author(s):  
Tim Persoons ◽  
Tadhg S. O’Donovan ◽  
Darina B. Murray
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Normal Velocity ◽  
Mean Flow ◽  
Stroke Length ◽  
Cooling Performance ◽  
Single Jet

An impinging synthetic jet can attain heat transfer rates comparable to a continuous jet, without net mass input. However it needs a forced cross-flow to supply fresh cooling medium. The vectoring effect of adjacent synthetic jets allows directing the flow by changing the phase between the jets. This study uses the vectoring effect of two adjacent synthetic jets to draw in fresh air, while maintaining high impingement cooling performance. The experimental approach applies infrared thermography and particle image velocimetry to quantify the local convective heat transfer and flow field, respectively. The heat transfer profiles for various phase differences have been compared to the mean flow field and wall-normal velocity fluctuation intensity. For a fixed operating point (stroke length and Reynolds number) and geometry, the cooling performance has been optimised for phase and jet-to-surface spacing, resulting in about 90% enhancement of the maximum and overall cooling rate compared to a single jet, without the need for external cross-flow forcing.

Dye visualisation of inclined and skewed synthetic jets in a cross flow

2005 ◽  
Vol 109 (1093) ◽  
pp. 147-155 ◽  
Author(s):  
S. Zhong ◽  
L. Garcillan ◽  
N. J Wood
Keyword(s):  
Reynolds Number ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Maximum Flow ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Wall Region ◽  
Control Effect ◽  
Hairpin Vortices ◽  
Near Wall

Abstract Dye visualisation of both inclined synthetic jets and skewed synthetic jets was undertaken in a cross-flow experiment and the results were compared with those of normal synthetic jets. The process of vortex roll-up near the orifice exit and how the structure develops and interacts with the cross-flow as it propagates downstream was investigated so as to obtain an understanding of the effect of orifice orientation on the behaviour of synthetic jets. The effects of varying Reynolds number, velocity ratio and Strouhal number due to changes in diaphragm displacements and freestream velocities on the characteristics of synthetic jets were also examined. It is observed that in comparison to the normal jets vortical structures produced by both inclined and skewed jets tend to stay closer to the near wall region where maximum flow control effect is required. In both cases, at a relatively low Reynolds number and velocity ratio the active structures produced by the synthetic jet appear to be hairpin vortices which turn into vortex rings that migrate away from the wall as the Reynolds number and velocity ratio increase. These hairpin vortices are persistent in the near wall region hence are believed to be desirable structures for delaying flow separation.

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