The Sound the Air Makes: High-Performance Tunable Filters Based on Air-Cavity Resonators

Air ventilation of submerged surfaces of ship hulls is a promising technique for drag reduction. To ensure high performance of air cavities in a broad range of operational conditions, the cavity properties can be controlled with help of compact hydrodynamic actuators. In this study, a potential flow theory is applied to model an air cavity formed behind a wedge-shaped cavitator under a horizontal wall imitating a ship bottom. By varying the wedge angle, it is possible to achieve states with maximum drag reduction at given operational conditions. The dependence of the optimal wedge angle on Froude number and hull trim is investigated. The air-cavity ability to reduce frictional drag is found to increase with rising flow speed and bow-down hull trim.

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STATIC CONTROL OF DRAG-REDUCING AIR CAVITIES WITH VARIABLE CAVITATOR SHAPE

The International Journal of Maritime Engineering ◽

10.5750/ijme.v161ia1.1081 ◽

2021 ◽

Vol 161 (A1) ◽

Author(s):

K I Matveev

Keyword(s):

Drag Reduction ◽

High Performance ◽

Wedge Angle ◽

Flow Speed ◽

Frictional Drag ◽

Air Cavity ◽

Operational Conditions ◽

Ship Hulls ◽

Air Ventilation ◽

Air Cavities

Air ventilation of submerged surfaces of ship hulls is a promising technique for drag reduction. To ensure high performance of air cavities in a broad range of operational conditions, the cavity properties can be controlled with help of compact hydrodynamic actuators. In this study, a potential flow theory is applied to model an air cavity formed behind a wedge-shaped cavitator under a horizontal wall imitating a ship bottom. By varying the wedge angle, it is possible to achieve states with maximum drag reduction at given operational conditions. The dependence of the optimal wedge angle on Froude number and hull trim is investigated. The air-cavity ability to reduce frictional drag is found to increase with rising flow speed and bow-down hull trim.

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Ultra Fast Raman Hyperspectral Imaging using Bragg Tunable Filters and a High Performance Emccd Camera

Biophysical Journal ◽

10.1016/j.bpj.2013.11.3390 ◽

2014 ◽

Vol 106 (2) ◽

pp. 613a ◽

Cited By ~ 1

Author(s):

Félix Thouin ◽

Frédéric Leblond ◽

Richard Martel ◽

Marc Verhaegen ◽

Olivier Daigle

Keyword(s):

Hyperspectral Imaging ◽

High Performance ◽

Tunable Filters ◽

Emccd Camera

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Highly Confined Love Waves Modes by Defects States in a Phononic Crystal Based on Holey-SiO2/ST-Cut Quartz Structure

Proceedings ◽

10.3390/proceedings2130729 ◽

2018 ◽

Vol 2 (13) ◽

pp. 729

Author(s):

Yu-Xin Liu ◽

Abdelkrim Talbi ◽

Philippe Pernod ◽

Olivier Bou Matar

Keyword(s):

Band Gap ◽

High Performance ◽

Quartz Substrate ◽

Phononic Crystal ◽

Optimal Choice ◽

Comsol Multiphysics ◽

Geometrical Parameters ◽

Transmission Spectra ◽

Cavity Resonators ◽

Made In

We investigate the properties of highly confined Love modes in a phononic crystal based on an array of holes made in SiO2 deposited on ST-cut Quartz substrate. An optimal choice of the geometrical parameters of the holes enables us to obtain wide stop-bands frequency for shear wave’s modes. The introduction of defect by removing lines of holes leads to nearly flat modes within the band gap and consequently paves the way to implement advanced design of electroacoustic filters and high-performance cavity resonators based on shear wave modes. The calculations are performed using finite element method based on the commercial software (COMSOL-Multiphysics). For transmission spectra, piezoelectric excitations are applied by considering the interdigital transducers, with results corroborating well the band structure predictions and the position of defects modes within the band gap.

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