scholarly journals Helmholtz Resonance Frequency of the Synthetic Jet Actuator

2021 ◽  
Vol 11 (12) ◽  
pp. 5666
Author(s):  
Paweł Gil ◽  
Joanna Wilk ◽  
Michał Korzeniowski
Keyword(s):  
Resonance Frequency ◽  
Cross Section ◽  
Synthetic Jet ◽  
Orifice Diameter ◽  
Helmholtz Resonance ◽  
Synthetic Jet Actuator ◽  
Synthetic Jet Actuators ◽  
Cross Section Area ◽  
Section Area ◽  
Jet Actuators

This paper presents the results of experimental investigations of 108 geometrical configurations of a loudspeaker-driven synthetic jet (SJ) actuator. The considered cases of the SJ actuator were characterized by a high coupling ratio. The experiment was performed to determine the impact of geometry on the Helmholtz resonance frequency. Geometrical parameters of the orifice diameter, orifice length, and cavity volume were changed within a wide range. The dependences of electrical and flow parameters that characterized the synthetic jet actuators as a function of the excitation frequency were also identified. The main goal of the research was to identify the optimal mathematical formula of the model to calculate the Helmholtz resonance frequency in the case of synthetic jet actuators. To determine the model that was characterized by the best fit of the experimental results, an additional geometrical dimensionless parameter, representing the ratio of the orifice cross-section area to the cross-section area of the cavity, was introduced. A significant impact of this parameter on the effective orifice length was noted. Based on the research findings, a model was obtained for which the results of the experiment were in the error range of ±6% for 95% of the measurement data. The obtained model is an improved version of the classical model used in the description of the resonance frequency in the case of a synthetic jet actuator. The model enables highly accurate determination of the Helmholtz resonance frequency at which the maximum synthetic jet actuator parameters occur.

scholarly journals Synthetic Jet Actuators with the Same Cross-Sectional Area Orifices-Flow and Acoustic Aspects

2021 ◽  
Vol 11 (10) ◽  
pp. 4600
Author(s):  
Emil Smyk ◽  
Joanna Wilk ◽  
Marek Markowicz
Keyword(s):  
Reynolds Number ◽  
Force Measurement ◽  
Reaction Force ◽  
Synthetic Jet ◽  
Cross Sectional ◽  
Synthetic Jet Actuators ◽  
Cross Section Area ◽  
Section Area ◽  
Jet Actuators ◽  
Measurement Results

In this paper, synthetic jet actuators (SJAs) with three different orifice shapes (circular, square, and slot) with the same cross-section area were investigated. The SJA efficiency and the synthetic jet (SJ) Reynolds number were calculated based on the time-mean reaction force measurement. The momentum velocity was measured with hot-wire anemometry and additionally, the sound pressure level (SPL) was measured. The efficiency was equal maximally to 5.3% for each orifice shape, but the square orifice characterized the higher Reynolds number. The compared centerline (axial) velocities and the radial velocity profile at a distance of 112 mm were similar for each orifice type. The SPL measurement results were surprisingly constant in relation to each other. The square orifice generates the lowest SPL, approximately 2.8dB lower than the circular orifice, and approximately 4.2dB lower than the slot orifice, at each investigated real power. Finally, the differences to other papers and limitations of the approach to comparing orifices presented in the present paper were indicated.

Numerical Evaluation of the Effectiveness of Micro Pulsating Water Jets for Cooling of Microchips

2009 ◽  
Author(s):  
F. L. Hew ◽  
V. Timchenko ◽  
J. A. Reizes ◽  
E. Leonardi
Keyword(s):  
Heat Transfer ◽  
Minimum Temperature ◽  
Impinging Jets ◽  
Synthetic Jet ◽  
Maximum Temperature ◽  
Distinct Advantage ◽  
Synthetic Jet Actuator ◽  
Synthetic Jet Actuators ◽  
Micro Channels ◽  
Jet Actuators

In this study the effects of having multiple synthetic jet actuators and multiple orifices in a single jet actuator on creating better flow mixing and improving heat transfer in micro-channels have been investigated numerically. Unsteady computations of laminar flow have been performed for two dimensional configurations of micro-channel open at either end. A constant heat flux of 1 MWm−2 at the top of the silicon wafer represented the heat generated by the microchip. Synthetic jet actuators were attached to the bottom wall of the channel, with the 50 μm wide orifice. It is shown that by using double orifices single synthetic jet actuator, the heat transfer enhancement in micro-channels can be greatly improved. At the end of 30 cycles of actuation, the maximum temperature in the wafer has been reduced by approximately 27 K and the minimum temperature on the bottom of the wafer has been reduced by approximately 19 K in comparison with the steady flow values. In comparison with a single orifice synthetic jet actuator, double orifices synthetic jet actuator led to an additional 10 K reduction of the maximum temperature in wafer and 4 K reduction of minimum temperature on the interface of the wafer and water. It was demonstrated that the number of synthetic jet actuators is not the main factor influencing the thermal performance. The crucial factor is the number of impinging jets generated from the orifice which encourages better mixing in the flow. However, there is a distinct advantage associated with having multiple jet actuators in that out of phase flow could be generated which led to even lower temperatures than the in-phase jets.

THE MECHANISM OF JET VECTORING USING SYNTHETIC JET ACTUATORS

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1619-1622 ◽  
Author(s):  
ZHEN-BING LUO ◽  
ZHI-XUN XIA
Keyword(s):  
Static Pressure ◽  
Deflection Angle ◽  
Control Mechanism ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Control Mechanisms ◽  
Synthetic Jet Actuator ◽  
Synthetic Jet Actuators ◽  
Jet Actuators ◽  
Main Factors

The control mechanism of jet vectoring using synthetic jet actuators is investigated. The final deflection angle of the primary jet is a result of the primary jet controlled by synthetic jets at three different regions. The lower static pressure near the primary jet exit induced by the synthetic jet, the entrainment and absorption of the primary jet fluid by the synthetic jet during the blowing and the suction stroke, the coupling and interaction between the vortices of synthetic jet and the shear layer of the primary jet are the main control mechanisms for the synthetic jet actuator vectoring a primary jet. The main factors influencing jet vectoring are analyzed and summarized, and a preparatory model for jet vectoring using synthetic jet actuator is presented.

A static compressible flow model of synthetic jet actuators

2007 ◽  
Vol 111 (1121) ◽  
pp. 421-431 ◽  
Author(s):  
H. Tang ◽  
S. Zhong
Keyword(s):  
Viscous Flow ◽  
Flow Regime ◽  
Compressible Flow ◽  
Flow Model ◽  
Synthetic Jet ◽  
Operating Parameters ◽  
Helmholtz Resonance ◽  
Synthetic Jet Actuators ◽  
Resonance Regime ◽  
Jet Actuators

Abstract In this paper, a simple static compressible flow model for circular synthetic jet actuators is described. It is used to undertake a systematic computational investigation of the effect of changing actuator geometrical and operating parameters on the magnitude of peak jet velocity at the orifice exit of an actuator whose diaphragm displacement and frequency are allowed to vary independently. It is found that, depending on the flow conditions inside the orifice duct, the actuator may operate in two distinct regimes, i.e. the Helmholtz resonance regime and the viscous flow regime. In the Helmholtz resonance regime, the resultant synthetic jet is generated by the mass physically displaced by the oscillating diaphragm coupled with the Helmholtz resonance in the actuator. In the viscous flow regime, the Helmholtz resonance is completely damped by viscous effect such that the jet is produced by the diaphragm oscillation alone. The relationship between actuator geometrical and operating parameters at the optimum condition which yields the maximum peak jet velocity at a given diaphragm displacement is also established for these two regimes. Finally, a preliminary procedure for designing synthetic jet actuators for flow separation control on an aircraft wing is proposed.

scholarly journals LEM Characterization of Synthetic Jet Actuators Driven by Piezoelectric Element: A Review

2017 ◽  
Author(s):  
Matteo Chiatto ◽  
Francesco Capuano ◽  
Gennaro Coppola ◽  
Luigi de Luca
Keyword(s):  
Piezoelectric Element ◽  
Synthetic Jet ◽  
Orifice Diameter ◽  
Cavity Pressure ◽  
Synthetic Jet Actuators ◽  
Lumped Element ◽  
Air Jet ◽  
Jet Actuators ◽  
Jet Velocity ◽  
Design And Manufacture

In the last decades synthetic jet actuators have gained much interest among the flow control techniques due to their short response time, high jet velocity and absence of traditional piping, that matches the requirements of reduced size and low weight. A synthetic jet is generated by the diaphragm oscillation (generally driven by a piezoelectric element) in a relatively small cavity, producing periodic cavity pressure variations associated with cavity volume changes. The pressured air exhausts through an orifice, converting diaphragm electrodynamic energy into jet kinetic energy. This review paper faces the development of various lumped-element models (LEMs) as practical tools to design and manufacture the actuators. LEMs can quickly predict device performances such as the frequency response in terms of diaphragm displacement, cavity pressure and jet velocity, as well as the efficiency of energy conversion of input Joule power into useful kinetic power of air jet. The actuator performance is analyzed also by varying typical geometric parameters such as cavity height and orifice diameter and length, through a suited dimensionless form of the governing equations. A comprehensive and detailed physical modeling aimed to evaluate the device efficiency is introduced, shedding light on the different stages involved in the process. Overall, the influence of the coupling degree of the two oscillators, the diaphragm and the Helmholtz’s one, on the device performance is discussed throughout the paper.

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.

scholarly journals An Overview of Synthetic Jet Under Different Clamping and Amplitude Modulation Techniques

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Itimad D. J. Azzawi ◽  
Artur J. Jaworski ◽  
Xiaoan Mao
Keyword(s):  
Amplitude Modulation ◽  
Power Input ◽  
Synthetic Jet ◽  
Geometrical Parameters ◽  
Helmholtz Resonance ◽  
Excitation Signal ◽  
Synthetic Jet Actuators ◽  
Optimization Study ◽  
Jet Actuators ◽  
Modulation Techniques

Abstract There is generally limited guidance available on the optimum clamping method for the diaphragms used in the synthetic jet actuators (SJAs). This paper describes the effects of clamping methods (O-rings, neoprene rubber washers and metal-to-metal clamping) on the actuator diaphragm displacement using Polytec scan vibrometer (PSV). Once the clamping type was implemented, an optimization study to examine the effect of geometrical parameters for three designs of synthetic jet actuators in quiescent conditions—in particular the number of orifices per cavity, the space between them, and their effects on the jet velocity—was performed. It has also been shown that with use the Helmholtz resonance of the cavity and amplitude modulation of the excitation signal, the actuator can exhibit a more significant “blowing” velocity at a reduced power input.

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