Development of a Variable Diameter Synthetic Jet Actuator

2014 ◽  
Author(s):  
Spencer O. Albright ◽  
Stephen A. Solovitz
Keyword(s):  
Synthetic Jet ◽  
Pneumatic Cylinder ◽  
Synthetic Jet Actuator ◽  
Variable Diameter ◽  
Image Velocimetry ◽  
Flow Speeds ◽  
Exit Speed ◽  
Zero Net Mass Flux ◽  
Piston Stroke ◽  
Oscillating Motion

Synthetic jet actuators use oscillating motion near a fixed orifice to produce a net axial momentum flux with zero net mass flux. Through strategic application, these devices can provide flow control, propulsive thrust, and impingement cooling. To improve this performance, a new actuator has been designed with a variable orifice size, which can potentially increase exit flow speeds. The jet is generated using a pneumatic cylinder, which is oscillated linearly near an orifice. The opening consists of a camera aperture, whose diameter can decrease by a factor of 18 with the aid of a second pneumatic cylinder. The system is capable of operating at frequencies up to 5 Hz while maintaining full piston stroke, and the phase between the piston and orifice motion can be varied from 0 to 180 degrees. The flow structure is investigated using phase-locked particle image velocimetry (PIV), which shows that simultaneous constriction of the exit can substantially increase the exit speed. The initial design is used with air flow but will be extended to water applications in the future.

Examination of a Variable-Diameter Synthetic Jet

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Spencer O. Albright ◽  
Stephen A. Solovitz
Keyword(s):  
Particle Image Velocimetry ◽  
Vortex Ring ◽  
Mass Flux ◽  
Particle Image ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Variable Diameter ◽  
Constant Diameter ◽  
Image Velocimetry ◽  
Jet Actuators

Synthetic jet actuators are used to produce net axial momentum flow without net mass flux. Through strategic application, such devices can be used for flow control, propulsive thrust, and cooling. A novel application uses a variable-diameter orifice to constrict the exiting flow, and the motion can be synchronized with the pulse of the jet. This device is examined using phase-locked particle image velocimetry (PIV), permitting investigation of the flow fields and momentum flow. When compared to fixed-diameter synthetic jets, the variable-diameter actuator produces a larger vortex ring that lingers nearer the aperture. In addition, the experiments show increased momentum when the aperture is contracted in phase with the pulsing jet, with peak levels more than twice that of a constant-diameter jet.

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.

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.

PIV MEASUREMENTS OF DUAL SYNTHETIC JETS ACTUATOR DRIVEN BY ELECTRICAL FACTORS

2009 ◽  
Vol 23 (03) ◽  
pp. 417-420 ◽  
Author(s):  
ZHEN-BING LUO ◽  
ZHI-XUN XIA ◽  
BING LIU ◽  
DE-QUAN WANG ◽  
JIAN-XIN HU ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Driving Voltage ◽  
Transfer Phase ◽  
Piv Measurements ◽  
Synthetic Jet Actuator ◽  
Arbitrary Phase ◽  
Image Velocimetry

A dual synthetic jets actuator driven by different electrical factors was investigated using particle image velocimetry (PIV). A transfer-phase and sub-frequency technique was provided to capture the arbitrary phase of the dual synthetic jets, and a transfer-phase to equal technique was provided to determine the phase of the dual synthetic jets. The results show that both the amplitude and frequency of the electrical forcing voltages vastly affect the flow-field of the dual synthetic jets actuator. Both the forcing frequency and the driving voltage amplitudes contribute to the pressure difference and the area of the lower pressure, which determines the interactions of dual synthetic jets. The dual synthetic jet actuator exits a circumscription of electrical factors in which the actuator works efficiently.

Jet vectoring using synthetic jets

2002 ◽  
Vol 458 ◽  
pp. 1-34 ◽  
Author(s):  
B. L. SMITH ◽  
A. GLEZER
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Control Surface ◽  
Piv Measurements ◽  
Synthetic Jet Actuator ◽  
Recirculating Flow ◽  
Air Jet ◽  
Image Velocimetry

The interaction between a conventional rectangular (primary) air jet and a co-flowing synthetic jet is investigated experimentally. The nozzles of both jets have the same long dimension but the aspect ratio of the synthetic jet orifice is 25 times larger. Detailed particle image velocimetry (PIV) measurements of the flow in the midspan plane show that primary jet fluid is directed into the synthetic jet orifice and the interaction between the jets leads to the formation of a closed recirculating flow domain. The concomitant formation of a low-pressure region between the jets results in deflection of the primary jet toward the actuator jet despite the absence of an extended control surface (e.g. a diffuser or collar) and is balanced by a force on the primary jet conduit. For a given synthetic jet strength and primary jet speed, the vectoring force depends mainly on the volume flow rate of primary jet fluid that is diverted into the synthetic jet actuator. This flow rate is regulated by restricting the flow of entrained ambient fluid using a small streamwise extension of the synthetic jet orifice that scales with the orifice width. The response of the primary jet to the imposed vectoring is investigated using stepped modulation of the driving signal. The characteristic vectoring time and vectoring angle decrease monotonically with primary jet speed.

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.

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.

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