High dynamic range whole-field turbulence measurements in impinging synthetic jets for heat transfer applications
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2010Citation:
Persoons, T., Farrelly, R., McGuinn, A. and Murray, D.B., High dynamic range whole-field turbulence measurements in impinging synthetic jets for heat transfer applications, 15th Int Symp on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 5-8 July, 2010, 12Download Item:
Lisbon2010_1710_FullPaper2.doc (Accepted for publication (author's copy) - Peer Reviewed) 2.841Mb
Abstract:
For applications requiring high local heat transfer rates, recent research has shown that impinging
synthetic jets perform comparably to continuous jets, yet without needing external mass flow input. In spite
of recent attention, the understanding of synthetic jet heat transfer mechanisms remains incomplete. The heat
transfer performance strongly depends on flow conditions (e.g. Reynolds number, stroke length), geometric
parameters (e.g. jet-to-surface distance, orifice shape). Furthermore, vortex trains of adjacent synthetic jets
can interact to establish flow vectoring and significant heat transfer enhancements. Most parameters (stroke
length, jet-to-surface distance, phase lag between adjacent jets) have a highly non-monotonic influence on
heat transfer performance.
Accurate whole-field turbulence and flow measurements are crucial to understanding the heat transfer
mechanisms, thereby enabling optimal design of synthetic jet based heat transfer applications. Particle image
velocimetry (PIV) is the preferred technique, using state of the art adaptive multi-grid correlation with
window deformation. However, the dynamic range of the conventional PIV approach is too limited to
accurately resolve both high velocities near the orifice and low turbulence intensities in the wall jet region.
This paper applies a simple and robust technique based on multiple pulse separation (MPS) double-frame
imaging. For the impinging jet flows under investigation, the MPS-PIV technique increases the dynamic
velocity range by more than an order of magnitude compared to a conventional multi-grid PIV measurement.
The technique is validated on a steady jet test case against LDV measurements.
The paper describes some advances in synthetic jet heat transfer by comparing turbulence intensity
distributions and local heat transfer rates. In this configuration with a wide velocity range, MPS PIV enables
whole-field measurements without sacrificing resolution in the low velocity regions (i.e. wall jet and
entrainment regions) which are crucial to understand the governing heat transfer mechanisms.
Sponsor
Grant Number
Science Foundation Ireland (SFI)
Author's Homepage:
http://people.tcd.ie/dmurrayhttp://people.tcd.ie/persoont
Description:
PUBLISHEDLisbon, Portugal
Other Titles:
15th Int Symp on Applications of Laser Techniques to Fluid MechanicsType of material:
Conference PaperAvailability:
Full text availableKeywords:
Mechanical Engineering, turbulence PIV, synthetic jetsSubject (TCD):
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