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Actuators
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Flow Control by Means of Synthetic Jet Actuators
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Flow Control by Means of Synthetic Jet Actuators

A special issue of Actuators (ISSN 2076-0825).

Deadline for manuscript submissions: closed (20 December 2021) | Viewed by 10279

Special Issue Editor

Prof. Dr. Luigi de Luca

E-Mail Website
Guest Editor
Department of Industrial Engineering, University of Naples “Federico II”, 80125 Napoli (NA), Italy
Interests: thermo-fluid dynamic stability; flow control; synthetic jet actuators; free surface flows
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The need for flow control is widely recognized in various fields of technological applications such as fluid dynamics, heat transfer, combustion, atomization, and others. The common goal to be achieved is the maximization of the performance of the engineering systems under design, for both safety and energy consumption reduction purposes. A class of modern active control actuators is clustered under the common term synthetic jet (SJ), meaning that the jet is synthetized within the fluid to be controlled without the use of any traditional pumping device. Piezo-driven and plasma (i.e., spark and dielectric barrier discharge (DBD)) actuators are currently the object of theoretical and experimental investigations. The recent literature has provided a huge amount of contributions related to the basic characterization of such devices, whilst the current ongoing research is devoted to various applications of flow control, addressing specific needs and issues. The aim of the present Special Issue is to collect original papers concerned with the application of various types of SJ actuators to flow control, without any limitation on the specific application field. Theoretical, numerical and experimental contributions are welcome, provided they deal with the interaction between the jet and the external fluid current to be controlled. Modern analysis concerned with POD, DMD, and low order modeling global stability are particularly encouraged, for both numerical and experimental data.

Prof. Luigi de Luca
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Actuators is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Synthetic jet actuator
  • Flow control
  • Piezo-driven device
  • Plasma spark jet device
  • Turbulence
  • Flow separation
  • Heat transfer
  • Mixing flow
  • Atomization
  • Proper orthogonal decomposition (POD)
  • Dynamic mode decomposition (DMD)
  • Low order modeling (LOM) global stability

Published Papers (4 papers)

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Research

20 pages, 2483 KiB  
Article
Combined Passive/Active Flow Control of Drag and Lift Forces on a Cylinder in Crossflow Using a Synthetic Jet Actuator and Porous Coatings
by Gearóid Farrell, Michael Gibbons and Tim Persoons
Actuators 2022, 11(7), 201; https://doi.org/10.3390/act11070201 - 19 Jul 2022
Cited by 5 | Viewed by 2129
Abstract
This paper combines a synthetic jet actuator (SJA) and a leeward porous coating to alter the aerodynamic forces on a cylinder in crossflow at Re = 4.2 × 104. While SJAs and porous coatings are known to be effective flow [...] Read more.
This paper combines a synthetic jet actuator (SJA) and a leeward porous coating to alter the aerodynamic forces on a cylinder in crossflow at Re = 4.2 × 104. While SJAs and porous coatings are known to be effective flow control methods in isolation, their combined effect has not been studied. A 2D numerical model was created of a cylinder with a SJA at 90° and 100° leeward porous coating. The model was validated using accompanying water tunnel tests. The combined model was tested for dimensionless frequencies 0.15 <f+< 4 and compared to reference models. For f+< 1, using only the SJA increases the cylinder drag coefficient (Cd). Combining a porous coating with the SJA in that regime lowers the Cd values by 15–21%, and causes an overall reduction in Cd compared to the smooth cylinder baseline case. However, using only the porous coating causes a superior 35% reduction in Cd. For f+> 1, the combined SJA and porous coating configuration did not differ from the SJA only configuration, achieving the largest drag reduction of 45% at f+ = 4. The flow control mechanisms of the SJA and porous coating do not combine constructively in this current setup. However, the porous coating is beneficial for f+< 1, causing an overall drag reduction even when the active SJA tends to increase drag. Full article
(This article belongs to the Special Issue Flow Control by Means of Synthetic Jet Actuators)
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20 pages, 3631 KiB  
Article
Experimental and CFD Characterization of a Double-Orifice Synthetic Jet Actuator for Flow Control
by Andrea Palumbo and Luigi de Luca
Actuators 2021, 10(12), 326; https://doi.org/10.3390/act10120326 - 08 Dec 2021
Cited by 7 | Viewed by 2729
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Flow Control by Means of Synthetic Jet Actuators)
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11 pages, 2912 KiB  
Communication
Experimental Investigations of Different Loudspeakers Applied as Synthetic Jet Actuators
by Paweł Gil and Joanna Wilk
Actuators 2021, 10(9), 224; https://doi.org/10.3390/act10090224 - 05 Sep 2021
Cited by 3 | Viewed by 1725
Abstract
The paper presents the preliminary results of the experimental investigation of four various loudspeakers used for driving the synthetic jet actuator. The parameters, characteristic synthetic jet velocity, pressure inside the cavity, device sound pressure level (SPL), and the heat sink thermal resistance, were [...] Read more.
The paper presents the preliminary results of the experimental investigation of four various loudspeakers used for driving the synthetic jet actuator. The parameters, characteristic synthetic jet velocity, pressure inside the cavity, device sound pressure level (SPL), and the heat sink thermal resistance, were presented for various input power and driving frequency. The resonance frequency was determined based on electrical impedance. The highest synthetic jet momentum velocity was achieved at diaphragm resonance frequency. The maximum sound pressure level was observed, also at resonant frequency. For the same real power delivered to the actuator and for its resonance frequency, the heat sink thermal resistance had the lowest value for the specific loudspeaker. In turn, the synthetic jet velocity reached maximum for this actuator. For all actuators tested, the sound pressure level was dependent on momentum velocity. Full article
(This article belongs to the Special Issue Flow Control by Means of Synthetic Jet Actuators)
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22 pages, 32439 KiB  
Article
Control of a Round Jet Intermittency and Transition to Turbulence by Means of an Annular Synthetic Jet
by Zuzana Antošová and Zdeněk Trávníček
Actuators 2021, 10(8), 185; https://doi.org/10.3390/act10080185 - 05 Aug 2021
Cited by 3 | Viewed by 2263
Abstract
This paper deals with active control of a continuous jet issuing from a long pipe nozzle by means of a concentrically placed annular synthetic jet. The experiments in air cover regimes of laminar, transitional, and turbulent main jet flows (Reynolds number ranges 1082–5181). [...] Read more.
This paper deals with active control of a continuous jet issuing from a long pipe nozzle by means of a concentrically placed annular synthetic jet. The experiments in air cover regimes of laminar, transitional, and turbulent main jet flows (Reynolds number ranges 1082–5181). The velocity profiles (time-mean and fluctuation components) of unforced and forced jets were measured using hot-wire anemometry. Six flow regimes are distinguished, and their parameter map is proposed. The possibility of turbulence reduction by forcing in transitional jets is demonstrated, and the maximal effect is revealed at Re = 2555, where the ratio of the turbulence intensities of the forced and unforced jets is decreased up to 0.45. Full article
(This article belongs to the Special Issue Flow Control by Means of Synthetic Jet Actuators)
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