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Actuators
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Synthetic Jet Actuators
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Synthetic Jet Actuators

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

Deadline for manuscript submissions: closed (31 October 2018) | Viewed by 34974

Special Issue Editors

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
Dr. Matteo Chiatto

E-Mail Website
Guest Editor
Department of Industrial Engineering, University of Naples Federico II, 80125 Napoli NA, Italy
Interests: modal decomposition; reduced-order models; flow control; synthetic jet actuators; gasdynamics; thermo-fluid dynamic stability
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It has been many years since Synthetic Jet (SJ) actuators have been used for active flow control, in many different applications. These devices are able to manipulate the flow, to modify its natural behavior over a surface, or in a particular environment, inducing a favorable variation of the aerodynamic forces. Their application field is extremely wide, including flow control, mixing enhancement, heat transfer and many others. Nowadays, different types of actuators have been developed, tested and applied in several engineering problems. These include, among others, the classical SJ devices, whose diaphragm movement is driven by piezo-electric elements, loudspeakers and latest plasma actuators (or sparkjets). This Special Issue is aimed at presenting a complete overview on “Synthetic Jet Actuators”, including their characterization, modelling and various applications.

Contributions are particularly encouraged related (but not limited) to:

  • numerical and experimental characterization of SJ actuators;
  • physical modeling of  SJ devices;
  • application of SJ actuators to engineering problems: flow control, drag reduction, heat transfer, liquid spray, acoustics;
  • SJ actuators for innovative applications (thrust devices);
  • innovative design of SJ actuators.

Prof. Luigi de Luca
Dr. Matteo Chiatto
Guest Editors

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 Jets
  • Plasma Synthetic Jets
  • Sparkjets
  • Active Flow Control
  • Actuators
  • Resonant Cavity
  • Drag Reduction
  • Heat Transfer
  • Micropropulsion
  • Acoustics

Published Papers (5 papers)

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Research

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17 pages, 2562 KiB  
Article
Validating a Reduced-Order Model for Synthetic Jet Actuators Using CFD and Experimental Data
by Tim Persoons, Rick Cressall and Sajad Alimohammadi
Actuators 2018, 7(4), 67; https://doi.org/10.3390/act7040067 - 28 Sep 2018
Cited by 6 | Viewed by 5890 | Correction
Abstract
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 [...] Read more.
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). Full article
(This article belongs to the Special Issue Synthetic Jet Actuators)
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15 pages, 2532 KiB  
Article
Measurements versus Numerical Simulations for Slotted Synthetic Jet Actuator
by Andrea Palumbo, Matteo Chiatto and Luigi De Luca
Actuators 2018, 7(3), 59; https://doi.org/10.3390/act7030059 - 11 Sep 2018
Cited by 14 | Viewed by 6080
Abstract
In many studies concerning synthetic jet flow fields the analysis is usually restricted to simple configurations, such as a single diaphragm oscillating in a cylindrical cavity, which is linked to the external environment with only one orifice/slot. Nonetheless, in many applications the requirement [...] Read more.
In many studies concerning synthetic jet flow fields the analysis is usually restricted to simple configurations, such as a single diaphragm oscillating in a cylindrical cavity, which is linked to the external environment with only one orifice/slot. Nonetheless, in many applications the requirement of small sizes and weights leads to many implementation issues, such as asymmetric actuator geometries, presence of several slots and diaphragms and irregular cavity shapes. Therefore, the design of a synthetic jet actuator for a specific flow control problem requires a dedicated study in order to characterize its behavior even in quiescent conditions. The aim of this work is to investigate the behavior of a novel synthetic jet actuator, composed of three independent diaphragms, acting on a single cavity, and linked to the external environment through four slots per diaphragm. The device has been studied in quiescent conditions, both numerically and experimentally. The experimental investigation has been carried out by means of hot-wire measurements. In particular, the distribution of the phase-averaged streamwise velocity along the slot spanwise direction has been detected near the slot exit plane. From the computational side, incompressible direct numerical simulations have been carried out using the open-source OpenFOAM code. The diaphragm motion is mimicked by a inhomogeneous inlet boundary condition, whose amplitude is chosen to match the experimental velocity at the exit plane. A fair agreement between the numerical and the experimental results is achieved for both the velocity field at the slot exit and the main non-dimensional parameters of the synthetic jet. After the validation, the numerical results are finally processed, to obtain information about the vortex motion in the external environment. Full article
(This article belongs to the Special Issue Synthetic Jet Actuators)
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19 pages, 5560 KiB  
Article
Experimental Measurement Benchmark for Compressible Fluidic Unsteady Jet
by Pablo Fernandez, Jerome Delva, Celestin Ott, Philipp Maier and Quentin Gallas
Actuators 2018, 7(3), 58; https://doi.org/10.3390/act7030058 - 10 Sep 2018
Cited by 1 | Viewed by 5601
Abstract
A benchmark of different measurement techniques is presented to characterize the dynamic response of a synthetic jet actuator working in compressible regime. The setup involves a piston-based synthetic jet, as well as the benchmarked measurements are hot-wire, cold-wire, Laser Doppler Anemometry, pressure transducer, [...] Read more.
A benchmark of different measurement techniques is presented to characterize the dynamic response of a synthetic jet actuator working in compressible regime. The setup involves a piston-based synthetic jet, as well as the benchmarked measurements are hot-wire, cold-wire, Laser Doppler Anemometry, pressure transducer, and Schlieren visualization. Measured flow temperatures range from 20 °C to 150 °C, pressure ranges from 0.5 atm to 4 atm, and velocity are up to 300 m/s. The extreme values of these ranges are reached in an oscillating fashion at a frequency ranging from 30 to 100 Hz. The measurements are pointing out the limitation of cold-wire measurements, due to its high thermic inertia. The results show consistency in the velocity measurements, within 10% in the worst case, between all measurement techniques and the errors are traced back to the calibration ranges, whose sensitivity is also studied. Full article
(This article belongs to the Special Issue Synthetic Jet Actuators)
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13 pages, 2380 KiB  
Article
Novel Nozzle Shapes for Synthetic Jet Actuators Intended to Enhance Jet Momentum Flux
by Jozef Kordík and Zdeněk Trávníček
Actuators 2018, 7(3), 53; https://doi.org/10.3390/act7030053 - 28 Aug 2018
Cited by 12 | Viewed by 6514
Abstract
An axisymmetric synthetic jet actuator based on a loudspeaker and five types of flanged nozzles were experimentally tested and compared. The first (reference) type of nozzle was a common sharp-edged circular hole. The second type had a rounded lip on the inside. The [...] Read more.
An axisymmetric synthetic jet actuator based on a loudspeaker and five types of flanged nozzles were experimentally tested and compared. The first (reference) type of nozzle was a common sharp-edged circular hole. The second type had a rounded lip on the inside. The third nozzle type was assembled from these two types of nozzles—it had a rounded lip on the inside and straight section on the outside. The fourth nozzle was assembled using orifice plates such that the rounded lips were at both inner and outer nozzle ends. The last nozzle was equipped with an auxiliary nozzle plate placed at a small distance downstream of the main nozzle. The actuators with particular nozzles were tested by direct measurement of the synthetic jet (SJ) time-mean thrust using precision scales. Velocity profiles at the actuator nozzle exit were measured by a hot-wire anemometer. Experiments were performed at eight power levels and at the actuator resonance frequency. The highest momentum flux was achieved by the nozzle equipped with an auxiliary nozzle plate. Namely, an enhancement was approximately 31% in comparison with an effect of the reference nozzle at the same input power. Furthermore, based on the cavity pressure and the experimental velocity profiles, parameters for a lumped element model (mass of moving fluid and pressure loss coefficient) were evaluated. These values were studied as functions of the dimensionless stroke length. Full article
(This article belongs to the Special Issue Synthetic Jet Actuators)
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Review

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34 pages, 1538 KiB  
Review
Plasma Synthetic Jet Actuators for Active Flow Control
by Haohua Zong, Matteo Chiatto, Marios Kotsonis and Luigi De Luca
Actuators 2018, 7(4), 77; https://doi.org/10.3390/act7040077 - 01 Nov 2018
Cited by 51 | Viewed by 9374
Abstract
The plasma synthetic jet actuator (PSJA), also named as sparkjet actuator, is a special type of zero-net mass flux actuator, driven thermodynamically by pulsed arc/spark discharge. Compared to widely investigated mechanical synthetic jet actuators driven by vibrating diaphragms or oscillating pistons, PSJAs exhibit [...] Read more.
The plasma synthetic jet actuator (PSJA), also named as sparkjet actuator, is a special type of zero-net mass flux actuator, driven thermodynamically by pulsed arc/spark discharge. Compared to widely investigated mechanical synthetic jet actuators driven by vibrating diaphragms or oscillating pistons, PSJAs exhibit the unique capability of producing high-velocity (>300 m/s) pulsed jets at high frequency (>5 kHz), thus tailored for high-Reynolds-number high-speed flow control in aerospace engineering. This paper reviews the development of PSJA in the last 15 years, covering the major achievements in the actuator working physics (i.e., characterization in quiescent air) as well as flow control applications (i.e., interaction with external crossflow). Based on the extensive non-dimensional laws obtained in characterization studies, it becomes feasible to design an actuator under several performance constraints, based on first-principles. The peak jet velocity produced by this type of actuator scales approximately with the cubic root of the non-dimensional energy deposition, and the scaling factor is determined by the electro-mechanical efficiency of the actuator (O(0.1%–1%)). To boost the electro-mechanical efficiency, the energy losses in the gas heating phase and thermodynamic cycle process should be minimized by careful design of the discharge circuitry as well as the actuator geometry. Moreover, the limit working frequency of the actuator is set by the Helmholtz natural resonance frequency of the actuator cavity, which can be tuned by the cavity volume, exit orifice area and exit nozzle length. In contrast to the fruitful characterization studies, the application studies of PSJAs have progressed relatively slower, not only due to the inherent difficulties of performing advanced numerical simulations/measurements in high-Reynolds-number high-speed flow, but also related to the complexity of designing a reliable discharge circuit that can feed multiple actuators at high repetition rate. Notwithstanding these limitations, results from existing investigations are already sufficient to demonstrate the authority of plasma synthetic jets in shock wave boundary layer interaction control, jet noise mitigation and airfoil trailing-edge flow separation. Full article
(This article belongs to the Special Issue Synthetic Jet Actuators)
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