1. Measurement of two-dimensional heat transfer and flow characteristics of an impinging sweeping jet
- Author
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Hyun Dong Kim, Kyung Chun Kim, and Sang Hyouk Kim
- Subjects
Fluid Flow and Transfer Processes ,Jet (fluid) ,Materials science ,Turbulence ,Astrophysics::High Energy Astrophysical Phenomena ,Mechanical Engineering ,Phosphor thermometry ,Reynolds number ,02 engineering and technology ,Mechanics ,Jet stream ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Nusselt number ,010305 fluids & plasmas ,Physics::Fluid Dynamics ,symbols.namesake ,Particle image velocimetry ,0103 physical sciences ,Heat transfer ,symbols ,High Energy Physics::Experiment ,0210 nano-technology - Abstract
This study experimentally explores the two-dimensional heat transfer characteristics of an impinging sweeping jet generated from a feedback–channel-type fluidic oscillator. The results were compared to those of a steady square jet. A phosphor thermometry technique was used to measure the surface temperature field on an aluminum plate for different Reynolds numbers and jet-to-wall spacing. A two-dimensional planar Particle Image Velocimetry (PIV) measurement of the sweeping impinging jet was also conducted to couple the flow characteristics and heat transfer performance. The local Nusselt number distributions on the flat plate were evaluated by converting the temperature fields. The heat transfer performance of the sweeping jet is much higher than that of the steady jet because the sweeping motion of the jet induces significant turbulent flow and clearly improves the thermal transport near the impingement plate. However, when the jet-wall spacing becomes greater than 5, the heat transfer performance of the sweeping jet drastically decreases due to the reduced impinging velocity, and the heat transfer of the steady square jet surpasses that of the sweeping jet. In the ensemble averaged velocity fields, two main jet streams are ejected to the plate like oblique impinging jets near the sidewalls of the exit because the jet flow is attached to sidewall one or the other for more than 70% of an oscillation period. There was high similarity between the ensemble averaged velocity profiles and the Nusselt number profiles.
- Published
- 2019