Micro Synthetic Jets as Effective Actuator

Micro Synthetic Jets as Effective Actuator
Author: Mehti Koklu
Publisher:
Total Pages: 276
Release: 2007
Genre: Jets
ISBN: 9780549069454

Due to lack of experimental studies on micro synthetic jets, validation of the current method is accomplished in two steps. In the first step, capabilities of the methodology are tested successfully by computing flowfields inside a microchannel, microfilter, and micro backward facing step. In the second step, a realistic modeling of a synthetic jet in macro flow conditions is validated with experimental results.

Investigation of Scaling Effects for a Synthetic Jet Actuator Using High and Low Fidelity Analyses

Investigation of Scaling Effects for a Synthetic Jet Actuator Using High and Low Fidelity Analyses
Author: Amandine Bourlier
Publisher:
Total Pages: 134
Release: 2010
Genre: Actuators
ISBN:

"This research presents as investigation on the scaling effects for synthetic jet actuators using Ansys-CFX and a lumped element model (LEM) ... A computational fluid dynamics (CFD) model was created, using Ansys-CFX, to be validated against referred publications ... Finally a test case was conducted with both models, velocity profile was extracted for future use in application of controlled separated flow over an airfoil using an actuator and optimal excitation parameters were obtained. More recently, synthetic jet actuators have also been investigated for applications on micro-air vehicles [MAVs] as micro-jet propulsion. The last application has been specifically targeted in this project. In particular, the optimization of synthetic jet actuators could lead to the design of Micro Air Vehicles (MAV) equipped with an array of synthetic jets for a complete control of the vehicle."--Abstract, P. 4.

A Reduced-Order Model for Efficient Simulation of Synthetic Jet Actuators

A Reduced-Order Model for Efficient Simulation of Synthetic Jet Actuators
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
Total Pages: 32
Release: 2018-08-29
Genre:
ISBN: 9781726159449

A new reduced-order model of multidimensional synthetic jet actuators that combines the accuracy and conservation properties of full numerical simulation methods with the efficiency of simplified zero-order models is proposed. The multidimensional actuator is simulated by solving the time-dependent compressible quasi-1-D Euler equations, while the diaphragm is modeled as a moving boundary. The governing equations are approximated with a fourth-order finite difference scheme on a moving mesh such that one of the mesh boundaries coincides with the diaphragm. The reduced-order model of the actuator has several advantages. In contrast to the 3-D models, this approach provides conservation of mass, momentum, and energy. Furthermore, the new method is computationally much more efficient than the multidimensional Navier-Stokes simulation of the actuator cavity flow, while providing practically the same accuracy in the exterior flowfield. The most distinctive feature of the present model is its ability to predict the resonance characteristics of synthetic jet actuators; this is not practical when using the 3-D models because of the computational cost involved. Numerical results demonstrating the accuracy of the new reduced-order model and its limitations are presented.Yamaleev, Nail K. and Carpenter, Mark H.Langley Research CenterACTIVE CONTROL; JET FLOW; FINITE DIFFERENCE THEORY; NAVIER-STOKES EQUATION; ACTUATORS; CAVITY FLOW; THREE DIMENSIONAL MODELS; COMPUTATIONAL GRIDS; TIME DEPENDENCE...

Synthetic and Hybrid Synthetic Jet Actutators

Synthetic and Hybrid Synthetic Jet Actutators
Author: Jozef Kordík
Publisher: LAP Lambert Academic Publishing
Total Pages: 220
Release: 2013
Genre:
ISBN: 9783659329104

Synthetic jet actuators and hybrid synthetic actuators are investigated in this book from both theoretical and experimental points of view. The main property observed for synthetic jet actuators is the frequency behavior of the velocity amplitude at the nozzle output of the actuator. This behavior was studied previously in many other publications; however, most of these papers have focused on actuators constrained by short stream-wise dimensions. Based on experiments, this book also describes the properties of actuators with longer stream-wise dimensions and introduces new mathematical models to characterize them. Hybrid synthetic jets are quite similar to synthetic jets, but they differ in the rectification of the flow in the nozzle. The rectification is achieved by additional fluidic diodes incorporated to the actuator. A measure of the flow rectification is the volumetric efficiency. This book introduces a new design for this kind of actuator that is tested experimentally; a very high volumetric efficiency is found at the second velocity resonance of the actuator.

Design Optimization Tool for Synthetic Jet Actuators Using Lumped Element Modeling

Design Optimization Tool for Synthetic Jet Actuators Using Lumped Element Modeling
Author: Quentin Gallas
Publisher: BiblioGov
Total Pages: 24
Release: 2013-07
Genre:
ISBN: 9781289244446

The performance specifications of any actuator are quantified in terms of an exhaustive list of parameters such as bandwidth, output control authority, etc. Flow-control applications benefit from a known actuator frequency response function that relates the input voltage to the output property of interest (e.g., maximum velocity, volumetric flow rate, momentum flux, etc.). Clearly, the required performance metrics are application specific, and methods are needed to achieve the optimal design of these devices. Design and optimization studies have been conducted for piezoelectric cantilever-type flow control actuators, but the modeling issues are simpler compared to synthetic jets. Here, lumped element modeling (LEM) is combined with equivalent circuit representations to estimate the nonlinear dynamic response of a synthetic jet as a function of device dimensions, material properties, and external flow conditions. These models provide reasonable agreement between predicted and measured frequency response functions and thus are suitable for use as design tools. In this work, we have developed a Matlab-based design optimization tool for piezoelectric synthetic jet actuators based on the lumped element models mentioned above. Significant improvements were achieved by optimizing the piezoceramic diaphragm dimensions. Synthetic-jet actuators were fabricated and benchtop tested to fully document their behavior and validate a companion optimization effort. It is hoped that the tool developed from this investigation will assist in the design and deployment of these actuators.

Experimental Analysis of a Synthetic Jet Actuator Under Different Configurations

Experimental Analysis of a Synthetic Jet Actuator Under Different Configurations
Author: Juan Sebastian Marin Quintero
Publisher:
Total Pages:
Release: 2017
Genre:
ISBN:

Boundary layer separation has always been an interesting topic to develop and understand, where the synthetic jets present a big potential to reduce the drag coefficients and increase the efficiency in the vehicles. The behavior of the synthetic jets can be varied by changing different aspects in the cavity such as the diameter and length of the neck and also by changing the parameters of the actuator as the frequency and the amplitude. An experimental research is presented which describes the experiments specifications, the different variations in the cavity and in the actuators and also the results according to the configuration used.

Adaptive Compensation of Nonlinear Actuators for Flight Control Applications

Adaptive Compensation of Nonlinear Actuators for Flight Control Applications
Author: Dipankar Deb
Publisher: Springer Nature
Total Pages: 129
Release: 2021-07-22
Genre: Technology & Engineering
ISBN: 9811641617

This book provides a basic understanding of adaptive control and its applications in Flight control. It discusses the designing of an adaptive feedback control system and analyzes this for flight control of linear and nonlinear aircraft models using synthetic jet actuators. It also discusses control methodologies and the application of control techniques which will help practicing flight control and active flow control researchers. It also covers modelling and control designs which will also benefit researchers from the background of fluid mechanics and health management of actuation systems. The unique feature of this book is characterization of synthetic jet actuator nonlinearities over a wide range of angles of attack, an adaptive compensation scheme for such nonlinearities, and a systematic framework for feedback control of aircraft dynamics with synthetic jet actuators.

Flow Control Via Synthetic Jet Actuation

Flow Control Via Synthetic Jet Actuation
Author: Adam Cole Miller
Publisher:
Total Pages:
Release: 2005
Genre:
ISBN:

An experimental investigation was undertaken to determine the ability of Synthetic Jet Actuators to control the aerodynamic properties of a wing. The Synthetic Jet Actuator (SJA) was placed at two separate positions on a wing comprised of a NACA0015 airfoil. The first of the jet positions is located at 12% of the chord, hereby referred to as the leading edge Synthetic Jet Actuator. The second exit position is located at 99% chord of an airfoil and hereby is referred to as the trailing edge Synthetic Jet Actuator. The two locations produced different benefits as the angle of attack of the wing was increased. The leading edge Synthetic Jet Actuator delayed the onset of stall of an airfoil, suppressing stall up to 25 degrees angle of attack. The control of the aerodynamic characteristics was achieved by influencing the amount of the separated flowfield region. The effects of the dynamic stall vortex were investigated with wind tunnel testing during the pitching motion of an airfoil to determine how the flow reacts dynamically. The trailing edge synthetic jet actuator was investigated as a form of low angle "hingeless" control. The study investigated the effect of the jet momentum coefficient on the ability of the synthetic jet to modify the lifting and pitching moment produced from the wind tunnel model. The data indicates that, with the present implementation, the SJA-jet flap generates moderate lift and moment coefficient increments that should be suitable for hinge- less control. It was also shown that, for the current experimental setup and a given jet momentum coefficient, continuous blowing is more effective than oscillatory blowing/sucking. The data shows that combining the SJA with a Gurney flap does not result in performance enhancement.

Experimental Study on the Use of Synthetic Jet Actuators for Lift Control

Experimental Study on the Use of Synthetic Jet Actuators for Lift Control
Author:
Publisher:
Total Pages: 94
Release: 2014
Genre: Dissertations, Academic
ISBN:

An experimental study on the use of synthetic jet actuators for lift control is conducted. The synthetic jet actuator is placed on the pressure side towards the trailing edge on a NACA 65(2)-415 airfoil representative of the cross section of an Inlet Guide Vane (IGV) in an industrial gas compressor. By redirecting or vectoring the shear layer at the trailing edge, the synthetic jet actuator increases lift and decreases drag on the airfoil without a mechanical device or flap. A compressor map that defines upper and lower bounds on operating velocities and airfoil dimensions, is compared with operating conditions of the low-speed wind tunnel at San Diego State University, to match gas compressor conditions in the wind tunnel. Realistic test conditions can range from Mach=0.12 to Mach= 0.27 and an airfoil chord from c=0.1 m to c=0.3 m. Based on the operating conditions, a final airfoil model is fabricated with a chord of c=0.1m. Several synthetic jet actuator designs are considered. A initial synthetic jet is designed to house a piezoelectric element with a material frequency of 1200 hz in a cavity with a volume of 4.47 cm33 a slot width of 0.25 mm, and a slot depth of 1.5 mm. With these dimensions, the Helmholtz frequency of the design is 1800Hz. Particle Image Velocimetry (PIV) experiments show that the design has a jet with a peak centerline jet velocity of 26 m/s at 750 Hz. A modified slant face synthetic jet is designed so that the cavity fits flush within the NACA airfoil surface. The slanted synthetic jet has a cavity volume of 4.67 cm3, a slot width of 0.25 mm, and a slot depth of 3.45 mm resulting in a Helmholtz frequency of 1170 hz for this design. PIV experiments show that the jet is redirected along the slant face according to the Coanda effect. A final synthetic jet actuator is directly integrated into the trailing edge of an airfoil with a cavity volume of 4.6 cm3, a slot width of 0.2 mm, and a slot depth of 1.6 mm. The Helmholtz frequency is 1450 Hz and matches closely with the piezoelectric element material frequency. The slot is designed so that actuator creates a jet normal to the airfoil surface. A wind tunnel model of the airfoil is 3D-printed with nine actuators integrated along the span of the airfoil. The synthetic jet slots cover 61% of the airfoil's span and the synthetic jet slots are located at a 13% chord upstream of the trailing edge. Tests are performed at multiple free stream velocities ranging from 17 m/s to 54 m/s which is the equivalent of an airfoil Reynolds number of Re=1:5_105 to Re=4:5_105. The integrated synthetic jet actuator increases lift. The increase is dependent on the freestream velocity, the actuation frequency, and angle of attack. For actuation at 1450 hz, and various freestream velocities, the synthetic jet actuator increases the lift by 2% at [lower case alpha]=7° to 7% at[lower case alpha] =15° . The synthetic jet increases L/D by 2% at[lower case alpha]=7° to 15% at [lower case alpha]=15° . Velocity contours obtained through PIV show that the synthetic jet turns the trailing edge shear layer similar to a Gurney flap, which increases lift. The synthetic jet reduces the wake velocity defect through injection of momentum, reducing the drag on the airfoil.