Predicting Heat Transfer for Low- and High-Frequency Central-Orifice Synthetic Jets

İkhlaq, Muhammad; Ghaffari, Omidreza; Arık, Mehmet

doi:10.1109/tcpmt.2016.2523809

Cited by 18 publications

(5 citation statements)

References 22 publications

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“…Hence, a continuous jet CFD model [1] will likely deviate from the ultrasonic micro-blower response. In the far field, the response will be more comparable, as partly revealed in the heat transfer correlation of Ikhlaq et al [9]. Here, the micro-blower performance was not affected by jet frequency for H/D > 10.…”

Section: Heat Transfermentioning

confidence: 52%

“…14 shows the variation of average Nusselt number versus frequency at H/D = 10. The heat transfer peaks at f = 25 kHz, which further suggests that the jet has its maximum flow rate here [9]. Off of this peak frequency, the heat transfer decreases by less than 10% between 24.5 kHz and 25.5 kHz.…”

Section: Heat Transfermentioning

confidence: 88%

“…For this ultrasonic blower, the unique multi-orifice structure results in a more complex frequency response. The micro-blower has a Helmholtz resonant frequency around 21 kHz when using the exhaust nozzle [10], and it has a resonance at 15.5 kHz for its inner cavity alone [9]. In principle, the design could match the diaphragm resonant frequency and the cavity Helmholtz resonance for the best performance, but that might lead to noise at frequencies below the audible limit of 20 kHz.…”

Section: Frequency Responsementioning

confidence: 99%

“…Thus, the microblower is designed to operate in a different mode. Usually, the first mode of the diaphragm is chosen for synthetic jet operation, but the micro-blower is operated at the third mode [9,14], likely to aid acoustics.…”

Section: Frequency Responsementioning

confidence: 99%

“…Piezoelectric designs generate rapid diaphragm motion, producing a high velocity jet stream that mixes with the ambient air. Unfortunately, effective synthetic jets often require operation at the actuator resonant frequency to maximize jet exit velocity, coinciding with the highest noise output [8][9][10]. For example, Arik [11] observed that a synthetic jet with a 1-mm orifice achieved its peak jet velocity of 90 m/s at a resonant frequency of 3.6 kHz.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

An investigation into flow and heat transfer of an ultrasonic micro-blower device for electronics cooling applications

Ghaffari

Solovitz

İkhlaq

et al. 2016

Applied Thermal Engineering

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Due to copyright restrictions, the access to the full text of this article is only available via subscription.As compact electronics increase in functionality, new electronics cooling approaches must be more effective, and they must be lower in form factor. In this paper, we investigated the cooling performance of a miniature ultrasonic micro-blower impinging upon a vertical heater. We studied the temperature response at different operating conditions, determining the optimal thermal conditions. We further examined the local flow field using the particle image velocimetry (PIV) technique at the same operating conditions, providing explanations for the heat transfer response in terms of the fluid dynamics. Heat transfer measurements show that the maximum cooling performance occurs at a jet-to-surface spacing ratio of 15 < H/D < 30, and the performance slowly decays when the jet is located further away. The preferred operating frequency of the piezoelectric cooling device occurs at an ultrasonic frequency of over 20 kHz, meaning that this device can function outside the human hearing range. The PIV results demonstrate that the jet profile in the near field deviates significantly from a traditional turbulent free jet. In the far field, it nearly matches the self-similar, fully-developed jet profile. The jet cooling performance is sensitive to the frequency, with the thermal performance dropping by a factor of six when varying by less than 1 kHz from the peak. At the optimal heat transfer condition, the coefficient of performance is measured at approximately three, which is lower than that of some synthetic jets.TÜBİTA

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Section: Heat Transfermentioning

confidence: 52%

Section: Heat Transfermentioning

confidence: 88%