Aerodynamic damping of sidewall bounded oscillating cantilevers

Eastman, Andrew; Kimber, Mark

doi:10.1016/j.jfluidstructs.2014.07.016

Cited by 15 publications

(5 citation statements)

References 30 publications

(43 reference statements)

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“…PIV experiments are conducted in a sealed box made of transparent acrylic plates (30 cm × 20 cm × 8 cm), large enough to reduce interference from the side walls [34]. Seeding particles are generated by heating a solution of water and glycerin (30% glycerin in volume).…”

Section: Experiments Parameters and Setupmentioning

confidence: 99%

Wake vortex regimes of a pitching cantilever plate in quiescent air and their correlation with mean flow generation

Ebrahimi

Eldredge

2019

Journal of Fluids and Structures

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Jet flows induced by oscillating cantilever plates enable power-efficient cooling enhancement and fluid acceleration. We report a combined experimental and numerical study of the vortex regimes present in the wake of a harmonically oscillating thin cantilever plate in a quiescent fluid and analyze their effect on the flow generation downstream. We use Particle Image Velocimetry (PIV) in conjunction with two-dimensional numerical simulations to investigate the vortex evolution around the trailing edge of the plates with different geometries and vibrational properties. Our observations suggest the existence of three distinct regimes in the wake: nonpropagating, intermediate and propagating. Comparing the temporal decay of the vortex circulation in different regimes shows that different mechanisms are involved in the formation of these vortical patterns. A regime map is proposed next, denoting the incident of each vortex regime as a function of relevant dimensionless parameters. Our analysis of the mean jet on the normal mid-plane, as quantified by the momentum-averaged Reynolds number Rejet, shows that the induced jet downstream the trailing edge is tightly correlated with the identified vortex regimes. The present study improves our understanding of vortex generation and propagation in oscillating cantilevers and facilitates optimized design and operation of piezoelectric fans and similar devices.

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Section: Experiments Parameters and Setupmentioning

confidence: 99%

Wake vortex regimes of a pitching cantilever plate in quiescent air and their correlation with mean flow generation

Ebrahimi

Eldredge

2019

Journal of Fluids and Structures

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“…Additional power is required to maintain the blade's amplitude whilst g <5mm, with demand exponentially increasing as g is reduced. The additional power requirement can be attributed to the added mass from the surrounding fluid, this is verified by observing the decreasing resonant frequency as g is reduced, and this cost always outweighs the benefits of increased thrust from an efficiency standpoint [29]. At small g, peak thrust is generated when ε=0mm, and reduces uniformly as ε is increased, either positively or negatively.…”

Section: Piezoelectric Fan Confinementmentioning

confidence: 85%

“…A blade's surroundings will also have a small effect on resonant frequency, due to the apparent mass increase caused by entrapped air [29]. This will be Wait et al [43] considered higher modes of oscillation.…”

Section: Piezoelectric Fan Parameters and Characteristicsmentioning

confidence: 99%

A review of piezoelectric fans for low energy cooling of power electronics

Hales

Jiang

2018

Applied Energy

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Power consumption from electrical devices increases year upon year, and as a result thermal management of power electronics is becoming ever more relevant. This review summarises the advancements made in the piezoelectric fan optimisation since their invention in the late 1970s. Energy consumption is highly relevant, and is an underlying theme throughout. Emphasis is placed on the methods undertaken to optimise designs for many different applications, and critical analysis of these processes is included. Comparison of data taken from different studies highlights the well-established rules of piezoelectric fan design and, more importantly for future advancements, also identifies the aspects of design which are not fully understood. Numerical modelling has become an

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“…The PIV experiments were conducted in a large sealed transparent chamber made of acrylic plates (30 cm × 20 cm × 8 cm) to reduce interference from the sidewalls (see Eastman & Kimber 2014). Seeding particles were generated by evaporating a solution of water and glycerine (30 % glycerine by volume).…”

Section: Experiments Parameters and Set-upmentioning

confidence: 99%