scholarly journals Novel Nozzle Shapes for Synthetic Jet Actuators Intended to Enhance Jet Momentum Flux

Actuators ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 53 ◽  
Author(s):  
Jozef Kordík ◽  
Zdeněk Trávníček
Keyword(s):  
Momentum Flux ◽  
Element Model ◽  
Velocity Profiles ◽  
Input Power ◽  
Synthetic Jet ◽  
Stroke Length ◽  
Synthetic Jet Actuator ◽  
Pressure Loss Coefficient ◽  
Nozzle Plate ◽  
Lumped Element Model

An axisymmetric synthetic jet actuator based on a loudspeaker and five types of flanged nozzles were experimentally tested and compared. The first (reference) type of nozzle was a common sharp-edged circular hole. The second type had a rounded lip on the inside. The third nozzle type was assembled from these two types of nozzles—it had a rounded lip on the inside and straight section on the outside. The fourth nozzle was assembled using orifice plates such that the rounded lips were at both inner and outer nozzle ends. The last nozzle was equipped with an auxiliary nozzle plate placed at a small distance downstream of the main nozzle. The actuators with particular nozzles were tested by direct measurement of the synthetic jet (SJ) time-mean thrust using precision scales. Velocity profiles at the actuator nozzle exit were measured by a hot-wire anemometer. Experiments were performed at eight power levels and at the actuator resonance frequency. The highest momentum flux was achieved by the nozzle equipped with an auxiliary nozzle plate. Namely, an enhancement was approximately 31% in comparison with an effect of the reference nozzle at the same input power. Furthermore, based on the cavity pressure and the experimental velocity profiles, parameters for a lumped element model (mass of moving fluid and pressure loss coefficient) were evaluated. These values were studied as functions of the dimensionless stroke length.

A Synthetic Jet Issuing From a Bio-Inspired Actuator With an Oscillating Nozzle Lip

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Zdeněk Trávníček ◽  
Zuzana Broučková
Keyword(s):  
Momentum Flux ◽  
Flux Measurement ◽  
Experimental Methods ◽  
Synthetic Jet ◽  
Operating Frequency ◽  
Working Fluid ◽  
Hot Wire ◽  
Synthetic Jet Actuator ◽  
Novel Variant ◽  
Flexible Diaphragm

A novel variant of a synthetic jet actuator (SJA) has been designed, manufactured, and tested. The novelty consists in a bio-inspired nozzle whose oscillating lip is formed by a flexible diaphragm rim. The working fluid is air, and the operating frequency is 65 Hz. The proposed SJA was tested by three experimental methods: phase-locked visualization of the nozzle lips, hot-wire anemometry, and momentum flux measurement using a precision scale. The results demonstrate advantages of the proposed SJA, namely, an increase in the momentum flux by 18% compared with that of a conventional SJA.

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.

A Numerical Study of 2-D Synthetic Jet Formation

Volume 4 ◽  
2004 ◽  
Author(s):  
Spencer R. Fugal ◽  
Barton L. Smith ◽  
Robert E. Spall
Keyword(s):  
Momentum Flux ◽  
Stokes Equations ◽  
Numerical Study ◽  
Length Change ◽  
Synthetic Jet ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Jet Formation ◽  
Stroke Length ◽  
Navier Stokes Equations

The formation of a two dimensional synthetic jet is studied numerically by solving the incompressible, unsteady, Reynolds-averaged, Navier-Stokes equations. Results for two exit geometries, a sharp exit and a rounded exit, and several dimensionless stroke lengths are compared. This study focuses on how the exit geometry and dimensionless stroke length change the following parameters: the power required to form the jet, the net momentum flux in the jet downstream of the exit, the formation threshold of the synthetic jet, and the location of the stagnation point during the suction portion of the cycle.

scholarly journals A computationally efficient hybrid 2D–3D subwoofer model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmad H. Bokhari ◽  
Martin Berggren ◽  
Daniel Noreland ◽  
Eddie Wadbro
Keyword(s):  
Hybrid Model ◽  
3D Model ◽  
Element Model ◽  
Acoustic Properties ◽  
Computational Time ◽  
Average Response ◽  
Frequency Range ◽  
Computationally Efficient ◽  
Lumped Element ◽  
Lumped Element Model

AbstractA subwoofer generates the lowest frequency range in loudspeaker systems. Subwoofers are used in audio systems for live concerts, movie theatres, home theatres, gaming consoles, cars, etc. During the last decades, numerical simulations have emerged as a cost- and time-efficient complement to traditional experiments in the design process of different products. The aim of this study is to reduce the computational time of simulating the average response for a given subwoofer design. To this end, we propose a hybrid 2D–3D model that reduces the computational time significantly compared to a full 3D model. The hybrid model describes the interaction between different subwoofer components as interacting modules whose acoustic properties can partly be pre-computed. This allows us to efficiently compute the performance of different subwoofer design layouts. The results of the hybrid model are validated against both a lumped element model and a full 3D model over a frequency band of interest. The hybrid model is found to be both accurate and computationally efficient.

scholarly journals Cephalopod‐Inspired Swimming Robot Using Dielectric Elastomer Synthetic Jet Actuator

2020 ◽  
Vol 22 (4) ◽  
pp. 2070014
Author(s):  
Chao Tang ◽  
Wentao Ma ◽  
Bo Li ◽  
Mingliang Jin ◽  
Hualing Chen
Keyword(s):  
Dielectric Elastomer ◽  
Synthetic Jet ◽  
Synthetic Jet Actuator
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