Cavity Effect of Synthetic Jet Actuators Based on Piezoelectric Diaphragm

2012 ◽  
Vol 225 ◽  
pp. 85-90 ◽  
Author(s):  
Md Nizam Dahalan ◽  
S. Mansor ◽  
Airi Ali
Keyword(s):  
Active Flow Control ◽  
Fast Response ◽  
Synthetic Jet ◽  
Synthetic Jet Actuator ◽  
Air Jet ◽  
Air Supply ◽  
Jet Velocity ◽  
Cavity Thickness ◽  
Zero Net Mass Flux ◽  
Cavity Effect

An active flow control technology known as synthetic jet actuator (SJA) is a zero-net mass-flux device to create pulsed jet that produces momentum to its surroundings and uses a vibrating diaphragm inside the cavity to generate an oscillatory flow through a small orifice. The performance of SJA depends on the design of an orifice and cavity, and oscillating membrane. SJA design based on piezoelectric diaphragm used in this project because of their size, lightweight, no need for external air supply, without the pipe complex, fast response time and low power consumption. This paper describes the cavity effect to SJA designs and experiments were performed to determine the air jet velocity produced through the orifice using a hot-wire anemometer at a different cavity thickness. The results demonstrate that the jet velocity increase would be better if the cavity thickness is reduced. However, more studies are needed to optimize the size of cavity and orifice for appropriate applications.

Experimental Design and Analysis of Bimorphs as Synthetic Jet Diaphragms

Aerospace ◽  
2006 ◽  
Author(s):  
Poorna P. Mane ◽  
Karla M. Mossi ◽  
Robert G. Bryant
Keyword(s):  
Pressure Gradient ◽  
Active Flow Control ◽  
Adverse Pressure Gradient ◽  
Synthetic Jet ◽  
Attractive Alternative ◽  
Geometrical Parameters ◽  
Synthetic Jet Actuator ◽  
Jet Velocity ◽  
Geometrical Factors ◽  
Driving Signal

Synthetic jet actuators are promising Active Flow Control (AFC) devices which could lead to saving millions of dollars in fuel consumption each year. The Bimorph piezoelectric actuators are an attractive alternative to other type of actuators as active diaphragms and are the focus of this work. Among the properties of a Bimorph actuator, a number of geometrical and physical external factors may have an effect on its performance as a synthetic jet actuator. Using statistical tools some of the physical and geometrical factors are evaluated as independent variables that may have an effect on the synthetic jet peak velocity, the dependent variable. Among the factors studied are the geometry of the synthetic jet cavity, the driving signal used to operate the active diaphragm, and the effect of a pressure gradient on the device. Among the six factors considered, the driving signal was found to have the highest effect on the peak jet velocity, and the factor of frequency proved to have a smaller effect. The cavity geometrical parameters were also relevant, a smaller orifice and a smaller cavity produce higher peak jet velocities. An adverse pressure gradient was also found to have a significant effect on peak jet velocity, diminishing its magnitude with increasing pressure.

scholarly journals Unsteady Simulation of a Synthetic Jet Actuator with Cylindrical Cavity Using a 3-D Lattice Boltzmann Method

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Hongbin Mu ◽  
Qingdong Yan ◽  
Wei Wei ◽  
Pierre E. Sullivan
Keyword(s):  
Lattice Boltzmann Method ◽  
Mass Flux ◽  
Lattice Boltzmann ◽  
Cylindrical Cavity ◽  
Active Flow Control ◽  
Control Device ◽  
Synthetic Jet ◽  
Synthetic Jet Actuator ◽  
Zero Net Mass Flux ◽  
Boltzmann Method

A synthetic jet actuator is a zero-net mass-flux device that imparts momentum to its surroundings and has proved to be a useful active flow control device. Using the lattice Boltzmann method (LBM) with the Bhatnagar-Gross-Krook (BGK) collision models, a 3-D simulation of a synthetic jet with cylindrical cavity employing a sinusoidal velocity inlet boundary condition was conducted. The velocity distributions are illustrated and discussed, and the numerical results are validated against previous experimental data. The computed results show the ingestion and expulsion flow over one working cycle as well as the evolution of vortices important to the control of the separated shear layer. Zero-net mass-flux behavior is confirmed.

Pressure Loading of Piezo Composite Unimorphs

2005 ◽  
Vol 888 ◽  
Author(s):  
Poorna Mane ◽  
Karla Mossi ◽  
Robert Bryant
Keyword(s):  
Active Flow Control ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Synthetic Jet Actuator ◽  
Active Pressure ◽  
Average Maximum ◽  
Non Local ◽  
Jet Velocity ◽  
Active Flow ◽  
Jet Velocities

ABSTRACTOver the past decade synthetic jets have emerged as a promising means of active flow control. They have the ability to introduce small amounts of energy locally to achieve non-local changes in the flow field. These devices have the potential of saving millions of dollars by increasing the efficiency and simplifying fluid related systems. A synthetic jet actuator consists of a cavity with an oscillating diaphragm. As the diaphragm oscillates, jets are formed through an orifice in the cavity. This paper focuses on piezoelectric synthetic jets formed using two types of active diaphragms, Thunder® and Lipca. Thunder® is composed of three layers; two metal layers, with a PZT-5A layer in between, bonded with a polyimide adhesive. Lipca is a Light WeIght Piezo Composite Actuator, formed of a number of carbon fiber prepreg layers and an active PZT-5A layer. As these diaphragms oscillate, pressure differences within the cavity as well as average maximum jet velocities are measured. These parameters are measured under load and no-load conditions by controlling pressure at the back of the actuator or the passive cavity. Results show that the average maximum jet velocities measured at the exit of the active cavity, follow a similar trend to the active pressures for both devices. Active pressure and jet velocity increase with passive pressure to a maximum, and then decrease. Active pressure and the jet velocity peaked at the same passive cavity pressure of 18kPa for both diaphragms indicating that the same level of pre-stresses is present in both actuators even though Lipca produces approximately 10% higher velocities than Thunder®.

STUDY THE ORIFICE EFFECTS OF A SYNTHETIC JET ACTUATOR DESIGN

2015 ◽  
Vol 77 (8) ◽  
Author(s):  
Md Nizam Dahalan ◽  
Shuhaimi Mansor ◽  
Muhammad Muzakkir Faiz Ali
Keyword(s):  
Coming Out ◽  
Active Flow Control ◽  
Input Voltage ◽  
Control Device ◽  
Synthetic Jet ◽  
Constant Input ◽  
Synthetic Jet Actuator ◽  
Jet Velocity ◽  
Actuator Design ◽  
Pulse Jet

The synthetic jet actuator is an active flow control device that is used to improve the aerodynamic performance on working surfaces such as wings, helicopter blades and ground vehicles. The performance of synthetic jet actuator depends on the design of the orifice and cavity, and the oscillating driver. Piezoelectric diaphragm was used as an oscillating driver because of its small size and easier installation. The focus of this project is to study the effects of orifice size and shape for a synthetic jet actuator design. The effects were studied on circular and rectangular shapes, and different sizes of orifice. Meanwhile, the configurations of the cavity are fixed. Experiments were performed to determine the maximum pulse jet velocity and turbulence intensities of the jet coming out of the orifice, driven by the Piezoelectric diaphragm at different frequencies, at constant input voltage of 2V. The experiment mainly involved the measurement of the exit pulse jet velocity using a hot-wire anemometer. The results demonstrated that the circular orifice produced higher maximum pulse jet velocity and smaller sizes orifices, both circular and rectangular, results in higher velocity jets.

scholarly journals Modal Reduction of Synthetic Jet Actuator Based Separation Control With Spectral POD

2020 ◽  
Author(s):  
Xuan Shi ◽  
Pierre Sullivan
Keyword(s):  
Flow Behavior ◽  
Spatial Scales ◽  
Active Flow Control ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Separation Control ◽  
Synthetic Jet Actuator ◽  
Zero Net Mass Flux ◽  
Active Flow

Abstract A synthetic jet actuator (SJA) is a zero-net-mass-flux device that imparts fluid momentum and is useful for active flow control (AFC). In many applications, airfoil performance is often limited or degraded by flow separation which is usually associated with loss of lift, increased drag, and kinetic energy losses. Therefore, it is of interest to investigate methods of separation region suppression with the forcing control of SJA. This paper studies the flow behavior of cross flow over an airfoil and how the addition of SJA influences flow characteristics. Using the Spectral Proper Orthogonal Decomposition and LES simulation, flow instabilities in the wake region are analyzed in their different temporal and spatial scales. The objective of this study is to explore the viability of SPOD for separation control and correlating the decomposed flow modes to the aerodynamic performance of airfoil.

Numerical Investigations of Active Flow Control Using Synthetic Jets on a Highly Loaded Compressor Stator Cascade

2010 ◽  
Author(s):  
Christoph Gmelin ◽  
Mathias Steger ◽  
Vincent Zander ◽  
Wolfgang Nitsche ◽  
Frank Thiele ◽  
...  
Keyword(s):  
Separation Bubble ◽  
Active Flow Control ◽  
Suction Side ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Time Resolved ◽  
Laminar Separation ◽  
Zero Net Mass Flux

Time-resolved Reynolds-Averaged Navier-Stokes simulations of a 3D stator compressor cascade are performed. At the design point of the airfoil under investigation, pronounced secondary flow effects are observed. Strong corner vortices emerge from the casing walls and the flow separates from the blade suction side towards the trailing edge. Transition from laminar to turbulent flow occurs within a laminar separation bubble. Using a commercial CFD software, the influence of the spatial resolution is investigated by means of a spanwise coarsening and refinement of the created mesh. Zero net mass flux synthetic jet actuation is used to control the separated regions. The work presents a variation of the temporal discretization and an analysis of the driving parameters of the actuation.

Analytical and Experimental Investigation of Different Synthetic Jet Actuator Configurations

Aerospace ◽  
2004 ◽  
Author(s):  
Sandra Ugrina ◽  
Alison Flatau
Keyword(s):  
Resonant Frequency ◽  
Smart Materials ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Laser Vibrometer ◽  
Synthetic Jet Actuator ◽  
Exit Nozzle ◽  
Geometry Configuration ◽  
Jet Velocity ◽  
Constant Temperature Anemometer

The ultimate goal of this project is to actively control the flow over a micro air vehicle using smart materials. MAVs are a new type of aircraft operating at Reynolds numbers of about 50,000 that are one to two orders of magnitude lower than encountered in larger aircraft. The intention is to implement smart structures and couple them with fluids to improve the deteriorated aerodynamics of MAVs and help improve efficiency, stability and maneuverability of such vehicles. The actuators used in this work for artificially controlling the boundary layer are piezoelectrically driven synthetic jets. We theoretically investigated and predicted the behavior of the synthetic jet as we changed the geometry and material property parameters of the actuator. Analytical results were then compared to the results obtained from the experiments. It is crucial to be able to accurately design a strong unimorph to be implemented as an active component of a synthetic jet actuator and design the geometry configuration of the cavity that will best couple with the chosen membrane. A condenser microphone, a constant temperature anemometer (CTA) and a laser vibrometer were used to quantify actuator performance. It was observed that the size of the cavity and the size and shape of the exit nozzle were related and the performance of the actuator increased when the structure was tuned such that the resonant frequency of the diaphragm and that of the cavity were close to matching. A square unimorph made of PZT-5H and bonded to a 0.20- mm brass shim maximized jet velocity for the actuators studied. Optimum direction of change in the volume and the dimensions of the nozzle will strongly depend on the resonant frequency of the membrane in use. In this situation, increasing either the volume of the cavity or the thickness of the nozzle made the two frequencies move away from each other producing reduction in jet velocity. Increasing the area of the nozzle, made the structure behave more as needed and was taken as a key parameter for tuning the base geometry of the device.

A Study on Synthetic Jet Actuator Diaphragm

2015 ◽  
Vol 14 (02) ◽  
pp. 91-105
Author(s):  
Siddhartha Sankar Deka ◽  
Rituraj Gautam ◽  
Anoop Singh ◽  
Gautam Kumar ◽  
Promod Kumar Patowari
Keyword(s):  
Structural Characteristics ◽  
Active Flow Control ◽  
Control Device ◽  
Synthetic Jet ◽  
Circular Disc ◽  
Response Analysis ◽  
Synthetic Jet Actuator ◽  
Piezoelectric Patch ◽  
Annular Disc ◽  
Patch Configuration

A synthetic jet actuator (SJA) is one of the most widely used active flow control device which uses a vibrating diaphragm enclosed within a cavity to generate the fluid jet. The effectiveness of the actuator greatly depends upon the design of cavity and orifice and the diaphragm properties. A lot of emphasis is being laid on the cavity and orifice design, but very few literatures can be found dealing with the diaphragm of the SJA. Thus, in this paper a study of the SJA diaphragm actuated by piezoelectric ceramics of different geometries is being presented. Three different diaphragm materials — brass, poly-silicon and aluminum and five different geometries of the piezoelectric actuators — annular disc shaped actuator patch, annular shaped actuator, rectangular shaped actuator patch and circular disc shaped actuator patch and two cantilever arrangements are being considered. A static analysis is carried out and a comparison of the parameters which affect the performance of the SJA is done. Frequency response analysis is also carried out to obtain a better understanding of the diaphragm's structural characteristics. The results thus obtained show that an annular disc piezoelectric patch configuration shows the best behavior as compared to the other actuator configurations and is closely followed by circular disc piezoelectric patch configuration.

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.

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