scholarly journals Synthetic jet actuator with two opposite diaphragms

2020 ◽  
Vol 24 (1) ◽  
pp. 17-25
Author(s):  
Emil Smyk ◽  
Sylwester Wawrzyniak ◽  
Kazimierz Peszyński
Keyword(s):  
Reynolds Number ◽  
Active Flow Control ◽  
Input Power ◽  
Synthetic Jet ◽  
Energetic Efficiency ◽  
Synthetic Jet Actuator ◽  
Jet Actuators ◽  
Device Use ◽  
Active Flow ◽  
Key Parameter

AbstractThe synthetic jet actuators are one of the most investigated types of actuators used in heat transfer and active flow control. The energetic efficiency of actuators is a key parameter determining the possibility of device use. The actuators with two or more diaphragms have higher efficiency than the actuators with only one. The paper presents the investigations of the acoustic synthetic jet actuator with two opposite diaphragms. In the paper, synthetic jet velocity, Reynolds number and the energetic efficiency as a function of oscillating actuator frequency, for a different cavity, orifice configuration and one real input power P0 = 2 W were studied. The possibility of theoretical calculation of first and second resonance frequency were checked. The coupling ratio for actuators was calculated. The maximum energetic efficiency was η = 8.67% and Reynolds number Re = 8503. The possibility of using the same dependencies and rules during the design of actuators with two opposite diaphragms as in the case of actuators with one diaphragm was demonstrated. The results may be useful in the design of the actuators of the two membranes.

The Effect of Orifice Angle and Cavity Dimension on Rectangular Synthetic Jet Actuators

2011 ◽  
Author(s):  
Pooya Kabiri ◽  
Douglas G. Bohl ◽  
Goodarz Ahmadi
Keyword(s):  
Particle Image ◽  
Vortical Structure ◽  
Active Flow Control ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Synthetic Jet Actuators ◽  
Image Velocimetry ◽  
Jet Actuators ◽  
Active Flow ◽  
Analytic Prediction

In the last decade, a great deal of interest has been focused on the application of synthetic jet actuators (SJA) for active flow control. SJAs delay separation by injecting vortex pairs into the cross flow and energizing the turbulent boundary layer. The goal of this study was to investigate the effects of the orifice angle on the performance of axisymmetric SJAs. The SJAs used in this experiment were composed of a piezoelectric (PZT) membrane, cavities and orifices. SJA’s with either a straight (90°) or angled (60°) orifices were characterized using hot-wire anemometry and Particle Image Velocimetry (PIV). It was found that the structure of the jet flow changed depending on the angle of the orifice with differences in the resulting vortical structure observed. The peak jet speed was found to be higher for the straight orifice than for the angled orifice contradicting the analytic prediction based on cavity dimension.

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®.

Development of synthetic jet actuators for active flow control at NASA Langley

2000 ◽  
Author(s):  
Fang-Jenq Chen ◽  
Chungsheng Yao ◽  
George Beeler ◽  
Robert Bryant ◽  
Robert Fox
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Synthetic Jet ◽  
Synthetic Jet Actuators ◽  
Jet Actuators ◽  
Active Flow

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

2016 ◽  
Author(s):  
Ricardo B. Torres ◽  
Gustaaf B. Jacobs ◽  
Michael J. Cave
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Shear Layer ◽  
Synthetic Jet ◽  
Inlet Guide Vane ◽  
Trailing Edge ◽  
Synthetic Jet Actuator ◽  
Synthetic Jet Actuators ◽  
Jet Actuators ◽  
Lift Control

An experimental study on the use of synthetic jet actuators for lift control on a generic compressor airfoil is conducted. A wind tunnel model of a NACA 65(2)-415 airfoil, representative of the cross section of an Inlet Guide Vane (IGV) in an industrial gas compressor, is 3D-printed. Nine synthetic jet actuators are integrated within a planar wing section with their slots covering 61% of pressure side of the airfoil span, located 13% chord upstream of the trailing edge. The Helmholtz frequency of the slot is matched closely with the piezoelectric element material frequency. The slot is designed so that the bi-morph actuation creates a jet normal to the airfoil surface. 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. Tests are performed at multiple Reynolds number ranging from Re=150,000 to Re=450,000. The increased lift of the integrated synthetic jet actuator is dependent on the Reynolds number and free stream velocity, the actuation frequency, and angle of attack. For actuation at 1450 Hz the synthetic jet actuator increases lift up to 7%. The synthetic jet increases L/D up to 15%. Velocity contours obtained through PIV show that the synthetic jet turns the trailing edge shear layer similar to a Gurney flap.

Active Flow Control of Dynamic Stall by Means of Jet Flow at Reynolds Number 106

2016 ◽  
Author(s):  
Ehsan Asgari ◽  
Mehran Tadjfar
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
Active Flow Control ◽  
Velocity Ratio ◽  
Jet Flow ◽  
Synthetic Jet ◽  
Dynamic Stall ◽  
Small Range ◽  
Active Flow ◽  
The Impact

In this study, we have examined slot location and velocity ratio of a tangential co-flow jet in dynamic stall motion of an airfoil at Reynolds number 1×106, for active flow control (AFC) purposes. The airfoil is the symmetrical NACA 0012 with a pitching motion between AOAs 5 deg. and 25 deg. about its quarter-chord with a sinusoidal motion. We have utilized Computational Fluid Dynamics (CFD) tool to numerically investigate the impact of jet location and jet velocity ratio on the aerodynamic coefficients. We have placed the jet location upstream the counter clock-wise (CCW) vortex which is formed during the upstroke motion near the leading-edge. We have also selected several other locations nearby to perform sensitivity analysis. Our results showed that placing the jet slot within a very small range upstream the CCW vortex has tremendous effects on both lift and drag, such that maximum drag which occurs at maximum incidences reduced by 80%. There was another unique observation: putting jet at separation point leads to an inverse behavior of drag hysteresis curve in upstroke and downstroke motions. Drag in downstroke motion is significantly lower than upstroke motion, whereas in uncontrolled case the converse is true. In addition, by implementing jet flow lift is significantly enhanced during both upstroke and downstroke motions. Finally, it should be indicated that this study provides initial steps in investigations of applying synthetic jet actuator (SJA) on a pitching airfoil at high Reynolds number 106 with effects of changing momentum ratio and SJA frequency, which will be presented in the near future.

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