scholarly journals Experimental and CFD Characterization of a Double-Orifice Synthetic Jet Actuator for Flow Control

Actuators ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 326
Author(s):  
Andrea Palumbo ◽  
Luigi de Luca
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Near Field ◽  
Vortex Motion ◽  
Synthetic Jet ◽  
Actuation Frequency ◽  
Velocity Amplitude ◽  
Resonance Frequencies ◽  
Double Orifice

The paper presents a joint experimental and numerical characterization of double-orifice synthetic jet actuators for flow control. Hot-wire measurements of the flow field generated by the device into a quiescent air environment were collected. The actuation frequency was systematically varied to obtain the frequency response of the actuator; its coupled resonance frequencies were detected and the velocity amplitude was measured. Direct numerical simulations (DNS) of the flow field generated by the device were subsequently carried out at the actuation frequency maximizing the jet output. The results of a fine-meshed parametric analysis are outlined to discuss the effect of the distance between the orifices: time-averaged flow fields show that an intense jet interaction occurs for small values of the orifice spacing-to-diameter ratio; phase-averaged velocity and turbulent kinetic energy distributions allow to describe the vortex motion and merging. A novel classification of the main regions of dual synthetic jets is proposed, based on the time- and phase-averaged flow behaviour both in the near field, where two distinct jets converge, and in the far field, where an unique jet is detected. The use of three-dimensional DNS also allows to investigate the vortex merging for low values of the jet spacing. The work is intended to provide guidelines for the design of synthetic jet arrays for separation control and impinging configurations.

Numerical and experimental characterization of a double-orifice synthetic jet actuator

Meccanica ◽  
2018 ◽  
Vol 53 (11-12) ◽  
pp. 2883-2896 ◽  
Author(s):  
Matteo Chiatto ◽  
Francesco Capuano ◽  
Luigi de Luca
Keyword(s):  
Synthetic Jet ◽  
Experimental Characterization ◽  
Synthetic Jet Actuator ◽  
Double Orifice

Experimental Characterization of a Micro-Blower for Flow Control

2019 ◽  
Author(s):  
Maria Wu ◽  
Pierre Sullivan
Keyword(s):  
Flow Control ◽  
Turbulent Jets ◽  
Synthetic Jet ◽  
Experimental Characterization ◽  
Continuous Mode ◽  
Mean Velocity ◽  
Burst Mode ◽  
Synthetic Jet Actuator ◽  
Image Velocimetry

Abstract A compact, lightweight, low-power piezoelectric micro-blower was characterized using particle image velocimetry to determine its flow control potential. The micro-blower has been operated in continuous mode as well as in burst mode using two different actuation frequencies. The maximum mean velocity measured with the micro-blower operating in continuous mode was approximately Ūmax = 13 m/s which occurred at the centerline at an approximate stream-wise location of x/d = 4. The velocity profiles in the developed region resemble those of turbulent jets. The momentum-flux from the micro-blower in continuous mode was significantly greater than a typical synthetic jet actuator which was successfully used for flow control, indicating that the micro-blower can impart the necessary momentum to be effective for flow control. With burst mode, the results show that the micro-blower could impart an even greater momentum.

Performance Characterization of a Piezoelectric Micro SJA

2009 ◽  
Vol 74 ◽  
pp. 223-226
Author(s):  
An Shik Yang ◽  
Jeng Jong Ro ◽  
Wei Han Chang
Keyword(s):  
Near Field ◽  
Vortex Pair ◽  
Computer Code ◽  
Synthetic Jet ◽  
Driving Voltage ◽  
Synthetic Jet Actuator ◽  
Air Jet ◽  
Jet Actuators ◽  
Jet Behavior

This paper aims to explore the synthetic jet behavior for a dual-diaphragm piezoelectrically driven micro synthetic jet actuator. For a sinusoidal actuation cycle at an operating frequency of 648 Hz, the synthetic jet flow pattern was simulated and compared with the visualized image and measured centerline velocity distribution to validate the computer code. The far-field flow structure was similar to a common continuous turbulent air jet; whereas, the unsteady formation of a vortex pair was predicted in the near-field. Numerical experiments were extended to appraise performance of micro synthetic jet actuators by varying the driving voltage, width of the slot and depth of the actuator cavity.

Near-field microwave microscopy for the characterization of dielectric materials

2014 ◽  
Vol 6 (6) ◽  
pp. 549-554 ◽  
Author(s):  
Jamal Rammal ◽  
Olivier Tantot ◽  
Nicolas Delhote ◽  
Serge Verdeyme
Keyword(s):  
Resonance Frequency ◽  
Dielectric Resonator ◽  
High Spatial Resolution ◽  
Near Field ◽  
Dielectric Materials ◽  
Microwave Microscopy ◽  
Knowing That ◽  
Resonance Frequencies ◽  
Microscopy Method

In this paper, we present a near-field microwave microscopy method for the characterization of dielectric materials samples in the Industrial, Scientific and Medical (ISM) band. The system proposed is composed of a probe coupled to a dielectric resonator (DR) operating in the TE011mode. Latter this is used to fix the resonance frequency of the resonator at 2.45 GHz. This system is used for the characterization of dielectric samples with accuracy and high spatial resolution, knowing that they do not have predetermined forms, but a small plane surface.The same device is used for a multi-frequency characterization (4–20 GHz) using resonance frequencies of the cavity instead of one resonance frequency of the DR.

Microfluidic Flow Control and Particle Transport Using Acoustically Actuated Bubbles in Teardrop Shaped Cavities

2012 ◽  
Author(s):  
Ali Hashmi ◽  
Garrett Heiman ◽  
Gan Yu ◽  
Hyuck-Jin Kwon ◽  
Jie Xu
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Flow Direction ◽  
Complex Flow ◽  
Actuation Frequency ◽  
Microfluidic Flow ◽  
Flow Speeds ◽  
Acoustic Actuation ◽  
Induced Flow ◽  
A Chain

It is well known that a symmetric microstreaming flow field will present in the vicinity of an acoustically actuated bubble. In this study, we demonstrate that oscillating microbubbles confined in teardrop-shaped cavities can result in a break in the symmetry of a microstreaming flow field. The teardrop cavity controls the size and shape of the bubble, regulating the volume and therefore its resonance frequency. If actuated in an acoustic field, the induced flow field can then be turned on and off by changing the acoustic actuation frequency. By harnessing the flow field directing capabilities of symmetry breaks and the switching properties of selective excitation of microbubbles, we generate and characterize a microfluidic switch for directing flow direction. We also show that a chain of multiple teardrop-shaped cavities can be used as a transport mechanism for directing particles spatially at high flow speeds. Our results demonstrate that teardrop cavities have great potential in future lab-on-a-chip devices by providing simple solutions to complex flow circuits for temporal and spatial flow control.

Active flow control by means of endwall synthetic jet on a high-speed compressor stator cascade

2017 ◽  
Vol 232 (6) ◽  
pp. 641-659
Author(s):  
Yong Qin ◽  
Yanping Song ◽  
Fu Chen ◽  
Ruoyu Wang ◽  
Huaping Liu
Keyword(s):  
Flow Control ◽  
Pressure Loss ◽  
Total Pressure ◽  
High Speed ◽  
Pressure Rise ◽  
Synthetic Jet ◽  
Total Pressure Loss ◽  
Momentum Exchange ◽  
Actuation Frequency ◽  
Flow Mixing

The underlying physics of the endwall synthetic jet in improving the aerodynamic performance of a high-speed compressor stator cascade is investigated in this paper. The effects of both injected momentum and actuation frequency are discussed in detail. In the investigations, the injected momentum is controlled by either changing the maximum jet velocity or modifying the tube diameter. Numerical results demonstrate that the streamwise momentum addition and flow mixing enhancement are the key factors of the endwall synthetic jet in improving the cascade performance. The high momentum fluid injected into the flow field can reenergize the passage flow, and the generated streamwise jet vortex contributes to the strengthening of flow mixing. Consequently, the momentum exchange between the low momentum fluid region and the main flow is enhanced and boundary layer separation on the blade suction surface is delayed. The loss characteristic in the corner region is improved as well. The intensified flow mixing will also increase the total pressure loss in the near-endwall region, which as a result will worsen the cascade performance, and hence the total effect of the endwall synthetic jet depends on the sum of its impacts. Moreover, the injected momentum and the actuation frequency have strong influences on the flow control effect. With the momentum coefficient and the reduced frequency being Cµ = 0.131% and F+ = 1.0, the reduction in total pressure loss coefficient and the increment in pressure rise coefficient are 7.3% and 3.3%, respectively.

Influence of Active Methods of Flow Control on Compressor Blade Cascade Flow

2008 ◽  
Author(s):  
Milan Matejka ◽  
Lukas Popelka ◽  
Pavel Safarik ◽  
Jiri Nozicka
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Side Wall ◽  
Positive Influence ◽  
Compressor Blade ◽  
Synthetic Jet ◽  
Main Flow ◽  
Synthetic Jet Actuator ◽  
Blade Cascade ◽  
Loss Coefficients

This paper deals with active methods of flow control, especially synthetic jet flow control. A synthetic jet was used for flow control in the compressor blade cascade to reduce the vortex structure and reduce the value of the loss coefficients. The output slot of the synthetic jet actuator was situated on the side wall on the connecting line of the leading edges of the blades. The direction of the synthetic jet was perpendicular to the main flow. The synthetic jet excitation is more effective and more efficient than a steady blowing or suction, and its great advantage is zero mass flux supplied to, or taken from the main flow. A positive influence of the synthetic jet on the flow field was proved. The flow field was also visualized.

scholarly journals Active flow control by means of synthetic jets on a highly loaded compressor cascade

2011 ◽  
Vol 225 (7) ◽  
pp. 897-908 ◽  
Author(s):  
V Zander ◽  
M Hecklau ◽  
W Nitsche ◽  
A Huppertz ◽  
M Swoboda
Keyword(s):  
Flow Control ◽  
Large Scale ◽  
Active Flow Control ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Experimental Investigations ◽  
Compressor Cascade ◽  
Actuation Frequency ◽  
Active Flow ◽  
Highly Loaded

This article presents the potential of active flow control to increase the aerodynamic performance of highly loaded turbomachinery compressor blades. Experimental investigations on a large-scale compressor cascade equipped with 30 synthetic jet actuators mounted to the sidewalls and the blades themselves have been carried out. Results for a variation of the inflow angle, the jet amplitude, and the actuation frequency are presented. The wake measurements show total pressure loss reductions of nearly 10 per cent for the synthetic jet actuation. An efficiency calculation reveals that the energy saved by actuation is nearly twice the energy consumption of the synthetic jets.

scholarly journals Some aspects of aerodynamic flow control using synthetic-jet actuation

2011 ◽  
Vol 369 (1940) ◽  
pp. 1476-1494 ◽  
Author(s):  
Ari Glezer
Keyword(s):  
Flow Control ◽  
Spatial Scales ◽  
Active Flow Control ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Base Flow ◽  
Bluff Bodies ◽  
Actuation Frequency ◽  
Zero Net Mass Flux ◽  
Aerodynamic Flow Control

Aerodynamic flow control effected by interactions of surface-mounted synthetic (zero net mass flux) jet actuators with a local cross flow is reviewed. These jets are formed by the advection and interactions of trains of discrete vortical structures that are formed entirely from the fluid of the embedding flow system, and thus transfer momentum to the cross flow without net mass injection across the flow boundary. Traditional approaches to active flow control have focused, to a large extent, on control of separation on stalled aerofoils by means of quasi-steady actuation within two distinct regimes that are characterized by the actuation time scales. When the characteristic actuation period is commensurate with the time scale of the inherent instabilities of the base flow, the jets can effect significant quasi-steady global modifications on spatial scales that are one to two orders of magnitude larger than the scale of the jets. However, when the actuation frequency is sufficiently high to be decoupled from global instabilities of the base flow, changes in the aerodynamic forces are attained by leveraging the generation and regulation of ‘trapped’ vorticity concentrations near the surface to alter its aerodynamic shape. Some examples of the utility of this approach for aerodynamic flow control of separated flows on bluff bodies and fully attached flows on lifting surfaces are also discussed.

Sign in / Sign up

Export Citation Format

Share Document