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.

THE MECHANISM OF JET VECTORING USING SYNTHETIC JET ACTUATORS

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1619-1622 ◽  
Author(s):  
ZHEN-BING LUO ◽  
ZHI-XUN XIA
Keyword(s):  
Static Pressure ◽  
Deflection Angle ◽  
Control Mechanism ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Control Mechanisms ◽  
Synthetic Jet Actuator ◽  
Synthetic Jet Actuators ◽  
Jet Actuators ◽  
Main Factors

The control mechanism of jet vectoring using synthetic jet actuators is investigated. The final deflection angle of the primary jet is a result of the primary jet controlled by synthetic jets at three different regions. The lower static pressure near the primary jet exit induced by the synthetic jet, the entrainment and absorption of the primary jet fluid by the synthetic jet during the blowing and the suction stroke, the coupling and interaction between the vortices of synthetic jet and the shear layer of the primary jet are the main control mechanisms for the synthetic jet actuator vectoring a primary jet. The main factors influencing jet vectoring are analyzed and summarized, and a preparatory model for jet vectoring using synthetic jet actuator is presented.

Compressibility Effects in Micro Synthetic Jets

2004 ◽  
Author(s):  
Victoria Timchenko ◽  
John Reizes ◽  
Eddie Leonardi
Keyword(s):  
Compressible Flows ◽  
Incompressible Flows ◽  
Pressure Rise ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Synthetic Jet Actuators ◽  
Jet Actuators ◽  
The Face ◽  
Compressibility Effects ◽  
Numerical Modeling Of Flows

Effects of including compressibility in the numerical modeling of flows produced by and in synthetic jet actuators — consisting of an oscillating diaphragm in a cavity with a small circular orifice in the face opposite the diaphragm — has been studied for axisymmetric configurations. Numerical results obtained on the assumption of incompressible and compressible flows with orifice diameters of the 20 and 40 μm and with an orifice length of 50 μm are compared. There are significant differences between compressible and incompressible flows for the 20 μm orifice, in that the jet velocity is greatly reduced when compressible flow is assumed, whereas the differences are much smaller in the 40 μm case. For both orifices the pressure rise upstream of the orifice is smaller when the fluid is compressible. It follows that results obtained on the assumption of incompressible flow cannot be extrapolated for micro-synthetic jet actuators handling compressible fluids.

Surface Synthetic Jet Actuators for Flow Control Applications in Internal Combustion Engines

2014 ◽  
Author(s):  
Paul Gilmore ◽  
Vishnu Baba Sundaresan
Keyword(s):  
Motion Control ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Combustion Engines ◽  
Charge Motion ◽  
Synthetic Jet Actuators ◽  
Geometrical Optimization ◽  
Jet Actuators

Charge motion in internal combustion engines is controlled by valves located near the engine ports in the intake path. The valve bodies are obstructions in the air-flow path and are a source of inefficiencies in the engine over its entire operating load. In order to achieve charge motion control without the use of valves, this research investigates the use of synthetic jet actuators to perform swirl and tumble of the air mass entering the cylinder. The purpose of this research is to design, test, and characterize a synthetic jet actuator, and determine the feasibility of using synthetic jet actuators in automotive air-intake systems. The accomplished work to date has led to geometrical optimization, fabrication of a prototype, and experimental investigation for determining jet velocities. The geometrical optimization of synthetic jets has led to a device with a thinner profile that allows it to be embedded in structures with thin (< 5mm) cross-sections and hence we refer to our synthetic jets as surface synthetic jets. It is shown here that air exiting the surface synthetic jets achieves sustained peak velocities well above 125 m/s. A variational principles-based approach is used to model the frequency response of the piezoelectric diaphragm, coupled with the lumped-parameter model for the surface synthetic jets and simulated using MATLAB Simulink®. The results of this model are validated with experimental results and extended to design charge motion control devices. From these results, it is anticipated that these surface synthetic jet actuators can achieve charge motion control using a radial array of surface synthetic jet actuators distributed around the intake runner.

scholarly journals Validating a Reduced-Order Model for Synthetic Jet Actuators Using CFD and Experimental Data

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 67 ◽  
Author(s):  
Tim Persoons ◽  
Rick Cressall ◽  
Sajad Alimohammadi
Keyword(s):  
Synthetic Jet ◽  
Operating Conditions ◽  
Reduced Order Model ◽  
Driving Voltage ◽  
Cavity Pressure ◽  
Order Model ◽  
Reduced Order ◽  
Synthetic Jet Actuators ◽  
Jet Actuators ◽  
Jet Velocity

Synthetic jet actuators (SJA) are emerging in various engineering applications, from flow separation and noise control in aviation to thermal management of electronics. A SJA oscillates a flexible membrane inside a cavity connected to a nozzle producing vortices. A complex interaction between the cavity pressure field and the driving electronics can make it difficult to predict performance. A reduced-order model (ROM) has been developed to predict the performance of SJAs. This paper applies this model to a canonical configuration with applications in flow control and electronics cooling, consisting of a single SJA with a rectangular orifice, emanating perpendicular to the surface. The practical implementation of the ROM to estimate the relationship between cavity pressure and jet velocity, jet velocity and diaphragm deflection and applied driving voltage is explained in detail. Unsteady Reynolds-averaged Navier Stokes computational fluid dynamics (CFD) simulations are used to assess the reliability of the reduced-order model. The CFD model itself has been validated with experimental measurements. The effect of orifice aspect ratio on the ROM parameters has been discussed. Findings indicate that the ROM is capable of predicting the SJA performance for a wide range of operating conditions (in terms of frequency and amplitude).

An experimental study on the behaviours of circular synthetic jets at low Reynolds numbers

2012 ◽  
Vol 226 (11) ◽  
pp. 2686-2700 ◽  
Author(s):  
Qingfeng Xia ◽  
Shan Zhong
Keyword(s):  
Reynolds Number ◽  
Silicone Oil ◽  
Reynolds Numbers ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Operating Conditions ◽  
Flow Visualisation ◽  
Stroke Length ◽  
Low Reynolds Numbers ◽  
Low Reynolds

In the work presented in this article, the behaviour of circular synthetic jets issuing into quiescent surrounding fluid at low Reynolds numbers is experimentally studied for potential mixing applications of synthetic jets at micro-scales or in highly viscous fluids. Sugar solutions and silicone oil are used as the flow media in order to achieve the required low Reynolds numbers. The conditions for jet instability, vortex rollup and synthetic jet formation are investigated using both flow visualisation techniques and particle image velocimetry, and the typical behaviour of synthetic jets at a Reynolds number around unity is also illustrated. The roles of Reynolds number, dimensionless stroke length and Stokes number in determining the characteristics of synthetic jets are examined and found to be largely consistent with the finding obtained at higher Reynolds numbers. Finally, a parameter map of synthetic jet flow patterns is produced based on the results from this study, which can be used to aid the choice of synthetic jet operating conditions for specific applications or anticipate if a desired vortex structure can be obtained at a given synthetic jet operating condition.

A PIV investigation of the characteristics of micro-scale synthetic jets

2007 ◽  
Vol 111 (1122) ◽  
pp. 519-528 ◽  
Author(s):  
F. Guo ◽  
S. Zhong
Keyword(s):  
Threshold Value ◽  
Stokes Number ◽  
Synthetic Jets ◽  
Operating Conditions ◽  
Performance Parameters ◽  
Stroke Length ◽  
Micro Scale ◽  
Linear Relationships ◽  
Macro Scale ◽  
Scaling Parameters

AbstractAlthough macro-scale synthetic jets are well studied, our knowledge of the behaviour of micro-scale synthetic jets is still extremely limited due to the difficulty in performing detailed measurements with a desirable spatial solution. In the work presented in this paper, a PIV study of the characteristics of synthetic jets issued into quiescent air from orifices of 5mm and 0·5mm diameter respectively is undertaken. It is found that the vortex rollup is much weaker for the 0·5mm jets due to their low Stokes number which results in a near parabolic exit velocity profile. To ensure an appreciable vortex rollup that is desirable for effective flow control, the actuator has to be operated at much higher frequencies to ensure that the Stokes number is greater than a certain threshold value. Furthermore the study shows that the characteristics of synthetic jets of different scales are identical when the dimensionless stroke length (L), Stokes number (S) and Reynolds number (ReL) are the same. On the basis of these scaling parameters, the finding acquired from the studies on macro-scale actuators can be applicable to micro-scale actuators, which are more difficult to measure. Finally, it is also found that although the linear relationships between (Land ReL) and actuator operating conditions observed for macro-scale synthetic jets are no longer valid for micro-scale synthetic jets, the linear relationships between the dimensionless jet performance parameters and (Land ReL) still exist for micro-scale synthetic jets.

A New Class of Synthetic Jet Actuators—Part I: Design, Fabrication and Bench Top Characterization

2005 ◽  
Vol 127 (2) ◽  
pp. 367-376 ◽  
Author(s):  
J. L. Gilarranz ◽  
L. W. Traub ◽  
O. K. Rediniotis
Keyword(s):  
Flow Separation ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Flow Separation Control ◽  
Synthetic Jet Actuators ◽  
New Class ◽  
Momentum Coefficient ◽  
Jet Actuators ◽  
In Series ◽  
Exit Slot

Although the potential of synthetic jets as flow separation control actuators has been demonstrated in the existing literature, there is a large gap between the synthetic jet actuators (SJA) used in laboratory demonstrations and the SJAs needed in realistic, full-scale applications, in terms of compactness, weight, efficiency, control authority and power density. In most cases, the SJAs used in demonstrations are either too large or too weak for realistic applications. In this work, we present the development of a new class of high-power synthetic jet actuators for realistic flow control applications. The operating principle of the actuator is the same as that of crankshaft driven piston engines, which makes a significant part of the technology necessary for the actuator development available off-the-shelf. The design of the actuator is modular and scalable. Several “building block” units can be stacked in series to create the actuator of the desired size. Moreover, active exit slot reconfiguration, in the form of variable exit slot width, decouples the actuator frequency from the actuator jet momentum coefficient and allows the user to set the two independently (within limits). Part I of this paper presents the design, fabrication and bench top characterization of the actuator. Several versions of the actuator were designed, built and tested, leading up to the development of a six-piston compact actuator that has a maximum power consumption of 1200 W (1.6 hp) and can produce (for the tested conditions) peak exit velocities as high as 124 m/s. In Part II, the actuator was housed in the interior of a NACA0015 profiled wing with a chord of 0.375 m (14.75 inches). The assembly’s performance in controlling flow separation was studied in the wind tunnel.

scholarly journals Impact of the Confinement Plate on the Velocity of Synthetic Jet

Actuators ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 208
Author(s):  
Emil Smyk ◽  
Robert Smusz
Keyword(s):  
Reynolds Number ◽  
Velocity Profile ◽  
Stokes Number ◽  
Synthetic Jet ◽  
Velocity Measurements ◽  
Synthetic Jet Actuators ◽  
Axial Velocity Profile ◽  
Jet Actuators ◽  
Constant Temperature Anemometer ◽  
The Impact

In the paper, the impact of the limitation of the environment around the office of synthetic jet actuators were tested. One short and three length orifices were tested and compared with and without confinement plate. In total, seven different synthetic jet actuators were investigated. The constant temperature anemometer was used for the velocity measurements. The synthetic jet was tested for the Reynolds number in the range of 2300 < Re < 19,500, and the Stokes number in the range of 46 < S < 62. The confinement plate decreased the velocity of synthetic jet depending on the actuator supply power even around 5%. However, the differences in axial velocity profile are slight and the impact of the confinement plate was visible only in the distance x/d < 4.

scholarly journals Using the PIV method to design synthetic jet actuators and investigate non-steady-state jet flow

2018 ◽  
Author(s):  
В.Г. Белова ◽  
◽  
А.Ю. Макаров ◽  
В.П. Маслов ◽  
В.А. Степанов ◽  
...  
Keyword(s):  
Steady State ◽  
Jet Flow ◽  
Synthetic Jet ◽  
Synthetic Jet Actuators ◽  
Piv Method ◽  
Jet Actuators
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