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.

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.

Vortex Shedding Control on a Three-Dimensional Ground Vehicle With Synthetic Jets

2016 ◽  
Author(s):  
Wenshi Cui ◽  
Zhigang Yang ◽  
Guojun Wang ◽  
Hua Zhou
Keyword(s):  
Vortex Shedding ◽  
Excitation Frequency ◽  
Three Dimensional ◽  
Synthetic Jet ◽  
Space Distribution ◽  
Ground Vehicle ◽  
Synthetic Jet Actuators ◽  
Synchronization Phenomenon ◽  
Momentum Coefficient ◽  
Jet Actuators

The study is mainly focused on the influence of the vortex shedding control of a three-dimensional ground vehicle by using synthetic jet actuators based on Large-eddy simulation. Excitation parameters for synthetic jet actuators, such as the excitation frequency, momentum coefficient and jet location, have an influence on vortex shedding control process, which lead to different unsteady flow phenomenon, vortex shedding frequency value and space distribution in the wake. Vortex shedding suppression and vortex-synchronization phenomenon have an influence on the pressure. Under present momentum coefficient, the excitation frequency plays an important role in the occurrence of vortex-synchronization phenomenon behind vertical base. As the momentum coefficient increase, the vortex-synchronization zone expands.

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 Fluidic-Oscillator-Based Pulsed Jet Actuators for Flow Separation Control

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 166
Author(s):  
Stephan Löffler ◽  
Carola Ebert ◽  
Julien Weiss
Keyword(s):  
Flow Separation ◽  
Oscillation Frequency ◽  
Current Knowledge ◽  
Industrial Applications ◽  
Synthetic Jets ◽  
Separation Control ◽  
Test Surface ◽  
Flow Separation Control ◽  
Pulsed Jet ◽  
Jet Actuators

The control of flow separation on aerodynamic surfaces remains a fundamental goal for future air transportation. On airplane wings and control surfaces, the effects of flow separation include decreased lift, increased drag, and enhanced flow unsteadiness and noise, all of which are detrimental to flight performance, fuel consumption, and environmental emissions. Many types of actuators have been designed in the past to counter the negative effects of flow separation, from passive vortex generators to active methods like synthetic jets, plasma actuators, or sweeping jets. At the Chair of Aerodynamics at TU Berlin, significant success has been achieved through the use of pulsed jet actuators (PJA) which operate by ejecting a given amount of fluid at a specified frequency through a slit-shape slot on the test surface, thereby increasing entrainment and momentum in a separating boundary layer and thus delaying flow separation. Earlier PJAs were implemented using fast-switching solenoid valves to regulate the jet amplitude and frequency. In recent years, the mechanical valves have been replaced by fluidic oscillators (FO) in an attempt to generate the desired control authority without any moving parts, thus paving the way for future industrial applications. In the present article, we present in-depth flow and design analysis which affect the operation of such FO-based PJAs. We start by reviewing current knowledge on the mechanism of flow separation control with PJAs before embarking on a detailed analysis of single-stage FO-based PJAs. In particular, we show that there is a fundamental regime where the oscillation frequency is mainly driven by the feedback loop length. Additionally, there are higher-order regimes where the oscillation frequency is significantly increased. The parameters that influence the oscillation in the different regimes are discussed and a strategy to incorporate this new knowledge into the design of future actuators is proposed.

Control of internal flow separation using synthetic jet actuators

2000 ◽  
Author(s):  
M. Amitay ◽  
D. Parekh ◽  
D. Pitt ◽  
V. Kibens ◽  
A. Glezer
Keyword(s):  
Flow Separation ◽  
Internal Flow ◽  
Synthetic Jet ◽  
Synthetic Jet Actuators ◽  
Jet Actuators

Control of Flow Separation and Its Associated Physics on a NACA0015 Using Synthetic Jet Actuators

2006 ◽  
Author(s):  
Wei Long Siauw ◽  
Jean Tensi ◽  
Se´bastien Bourgois ◽  
Jean-Paul Bonnet ◽  
Jean-Marc Breux ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Flow Separation ◽  
Laser Light ◽  
Laser Sheet ◽  
Synthetic Jet ◽  
Chord Length ◽  
Flow Physics ◽  
Synthetic Jet Actuators ◽  
Jet Actuators

Wind tunnel flow control experiments are conducted on two NACA0015 airfoil models, one of which having a chord length of 1.0m and the other having a chord of 0.35m, with the aim of exploring the separated flow physics and delaying flow separation. The larger model is tested in a low speed wind tunnel, measuring 1.25m by 1.25m at a Reynolds number of 0.4 and 0.27 million. This model is used to provide a quick proof of concept concerning the efficiency of various synthetic jet designs. Laser light visualization and Particle Image Velocimetry (PIV) studies are performed on this model. The synthetic jet actuators implemented (mechanically and acoustically generated) is realized through holes (2 and 3mm in diameter). The actuators are positioned at 20% or 70% of chord length from the leading edge for controlling separation at incidences between 12° and 15°. Flow separation delay and reattachment, depending on the frequency and momentum of the synthetic jet are observed qualitatively via laser sheet visualization in all cases. The efficiency of the actuator is quantified via the extent of separation observed with the PIV measurements. The technique of Proper Orthogonal Decomposition (POD) is applied to further reveal the large eddies in the separated shear layer and its interaction with the boundary layer. The smaller model is tested in a larger wind tunnel measuring 2.4m by 2.6m at a Reynolds number of 0.9 million. This is a more realistic flow condition with minimal wall and aspect ratio influence as compared to the larger model. The main experimental objective concerning this model is to quantify the baseline aerodynamic of the NACA0015 before implementation of synthetic jets. Laser light and surface oil visualizations are performed. Measurements concerning surface pressure and wake velocity characteristics are also made for this model. The lift of which is estimated via the integration of surface static pressure and the drag is estimated by wake survey technique using a pitot tube that is made to traverse in the wake. In addition, time resolved data are obtained in the wake of the airfoil by means of hotwires. Both hotwire measurement reveal typical Strouhal number of 0.34–0.4. These results are extrapolated to the large airfoil for interpretation of the flow physics during control. To sum up, the main results in the current study highlight the characteristics of the baseline airfoil and the ability of synthetic jet actuator techniques to obtain significant delay of the separation.

Sign in / Sign up

Export Citation Format

Share Document