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

Emil Smyk,Marek Markowicz,Joanna Wilk

doi:10.3390/app11104600

Abstract

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.

Highlights

The synthetic jet actuator (SJA) is a simple device consisting of only three parts: cavity, the orifice or nozzle, and the movable or deformable element
The modification of SJA cavity dimensions [5] and shape [6] both have an impact on the produced SJ, but the modification of the orifice is much easier and more important in terms of SJA application and design than the other two possibilities
The SJA can be used for enhanced heat transfer [7,8,9], mixing [10,11,12], or broadly defined active flow control [13,14,15]

Summary

Introduction

The synthetic jet actuator (SJA) is a simple device consisting of only three parts: cavity, the orifice or nozzle (one or many), and the movable or deformable element. The modifications of shape, the number, or the dimension of cavity or orifice may significantly change the parameters of the generated synthetic jet (SJ). The use of more than one movable or deformable element is possible and beneficial [3,4], but this can cause a significant increase in the actuator size especially in the case of mechanics and acoustic actuators, and limit their applicability. The modification and increasing of the SJA parameters are important, especially for their application. The SJA can be used for enhanced heat transfer [7,8,9], mixing [10,11,12], or broadly defined active flow control [13,14,15]

Methods

Results

Conclusion