January 01, 2017

Aerodynamic Performance of a Vibrating Piezoelectric Blade under Varied Operational and Confinement States

  • Jeffers N.
  • Stafford J.

This paper investigates the aerodynamic performance of a piezoelectrically actuated cantilever blade operating in the first mode of vibration. Bulk air moving capability and local velocity field features have been experimentally measured for different operational conditions and blade confinement states. A testing facility has been developed to determine the pressure- flow rate characteristics of a vibrating blade and simultaneously conduct particle image velocimetry. Under high system resistance, similar to that found in densely packed electronics, flow reversal occurs at the blade outlet region analogous to stall. This is accompanied by increased local unsteadiness in the air flow being emitted. Local turbulence intensity increases by 50% between maximum flow rate and maximum efficiency operating points. The introduction of confinement around a vibrating blade reduces bulk air moving capability significantly, with pressure rise and volumetric flow rate measured as low as 20% of what can be achieved for an unconfined blade. However, there is an accompanying change in spatial velocity distribution which focuses the flow normal to the outlet. This has potentially beneficial uses for targeted electronics cooling applications. The findings identify the relationship between local and bulk air flow characteristics that ultimately provides information about the sensitivity of this type of air moving device in practical installations.

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Recent Publications

August 09, 2017

A Cloud Native Approach to 5G Network Slicing

  • Francini A.
  • Miller R.
  • Sharma S.

5G networks will have to support a set of very diverse and often extreme requirements. Network slicing offers an effective way to unlock the full potential of 5G networks and meet those requirements on a shared network infrastructure. This paper presents a cloud native approach to network slicing. The cloud ...

August 01, 2017

Modeling and simulation of RSOA with a dual-electrode configuration

  • De Valicourt G.
  • Liu Z.
  • Violas M.
  • Wang H.
  • Wu Q.

Based on the physical model of a bulk reflective semiconductor optical amplifier (RSOA) used as a modulator in radio over fiber (RoF) links, the distributions of carrier density, signal photon density, and amplified spontaneous emission photon density are demonstrated. One of limits in the use of RSOA is the lower ...

July 12, 2017

PrivApprox: Privacy-Preserving Stream Analytics

  • Chen R.
  • Christof Fetzer
  • Le D.
  • Martin Beck
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How to preserve users' privacy while supporting high-utility analytics for low-latency stream processing? To answer this question: we describe the design, implementation and evaluation of PRIVAPPROX, a data analytics system for privacy-preserving stream processing. PRIVAPPROX provides three properties: (i) Privacy: zero-knowledge privacy (ezk) guarantees for users, a privacy bound tighter ...