scholarly journals Acoustic multi-layer Helmholtz resonance metamaterials with multiple adjustable absorption peaks

2021 ◽  
Vol 118 (24) ◽  
pp. 241904
Author(s):  
Haiqin Duan ◽  
Xinmin Shen ◽  
Enshuai Wang ◽  
Fei Yang ◽  
Xiaonan Zhang ◽  
...  
Keyword(s):  
Helmholtz Resonance

Tunable underwater acoustic metamaterials via quasi-Helmholtz resonance: From low-frequency to ultra-broadband

2021 ◽  
Vol 118 (7) ◽  
pp. 071904
Author(s):  
Mingyu Duan ◽  
Chenlei Yu ◽  
Fengxian Xin ◽  
Tian Jian Lu
Keyword(s):  
Low Frequency ◽  
Acoustic Metamaterials ◽  
Underwater Acoustic ◽  
Helmholtz Resonance

The Helmholtz Resonance Theory of Hearing

Nature ◽  
1934 ◽  
Vol 133 (3374) ◽  
pp. 983-983
Author(s):  
E. B. WEDMORE
Keyword(s):  
Resonance Theory ◽  
Helmholtz Resonance

A Quasi-Standing-Wave Phenomenon Due to Oscillating Internal Flow

1980 ◽  
Vol 102 (1) ◽  
pp. 70-77 ◽  
Author(s):  
D. Rockwell ◽  
A. Schachenmann
Keyword(s):  
Standing Wave ◽  
Acoustic Waves ◽  
Wave Amplitude ◽  
Wave Pattern ◽  
Settling Chamber ◽  
Exhaust Pipe ◽  
Axisymmetric Cavity ◽  
Vortical Structures ◽  
Helmholtz Resonance ◽  
Standing Wave Pattern

The objective of this investigation is to characterize a quasi-standing-wave pattern having a wavelength two orders of magnitude smaller than the corresponding acoustic wavelength, and relate it to the presence of: a) a downstream travelling wave due to vortical structures generated in a free shear layer, and b) downstream and upstream propagating acoustic waves. In this experiment, the vortical structures were generated by flow past an axisymmetric cavity and their influence extended downstream through the exhaust pipe. The amplitudes of the acoustic waves were associated with Helmholtz resonance of the upstream settling chamber. A linear theory models well the measured amplitude and phase distributions of the fluctuating velocity in the core flow. As system resonance is approached, the ratio of vortex wave amplitude to acoustic wave amplitude decreases. The consequence is an increase in the magnitude and gradient of the phase change across the node, or amplitude minimum, of the resultant standing-wave pattern. In addition, the peak-to-peak amplitude of the quasi-standing-wave increases. A variety of internal (and external) flow systems, including unsteady phenomena in wind tunnels, may be subject to this flow mechanism when the frequency of coherent vortex formation in the test section lies near the Helmholtz resonance frequency of the upstream settling (or plenum) chamber.

Helmholtz Resonance Based Micro Electrostatic Actuators for Compressible Gas Control: A Microjet Generator and a Gas Micro Pump

2010 ◽  
Vol 7 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Hanseup Kim ◽  
Khalil Najafi ◽  
Luis P. Bernal
Keyword(s):  
Total Power ◽  
Maximum Pressure ◽  
Air Velocity ◽  
Electrostatic Actuators ◽  
Helmholtz Resonance ◽  
Micro Pump ◽  
Resonant Behavior ◽  
In Series ◽  
Instantaneous Pressure ◽  
Gas Molecules

This paper reports Helmholtz-resonance based micro electrostatic actuators to control compressible gaseous fluids in the micro scale. Particularly, it discusses design, fabrication, and testing results of two electrostatic actuators: a micro jet generator and an integrated peristaltic multistage micro pump. These electrostatic actuators vibrate a micro membrane in a micro chamber at a high frequency (>10 kHz), and easily induce the resonant behavior of compressible gases in the chamber. Such resonant behavior, often called the Helmholtz resonance, can repeatedly create instantaneous pressure in equilibrium between the inside and outside of the chamber and cause gas to rapidly exit the chamber, forming a collimated jet. The developed micro jet generator consists of multiple acoustic chambers in parallel; produces directional gas momentum from each chamber by utilizing the Helmholtz resonance; and collectively entrains nearby gas molecules to form a gas stream. The fabricated micro jet generator has a footprint of 1.6 × 1.6 cm2 and contains 25 acoustic micro thrusters. It operates using a 140 V and 70 kHz sinusoidal signal and produces a thrust of 55.6 μN, a maximum air velocity of 1.2 m/s, and consumes power of 3.11 mW. The developed micro pump consists of multiple acoustic chambers in series and produces a high total pressure by accumulating pressures across the multiple chambers, while maintaining high flow rates utilizing the fluidic resonance of each pumping chamber. The fabricated 18-stage pump produces the maximum air flow rate of 4.0 sccm and maximum pressure differentials of 17.5 kPa with total power consumptions of only 57 mW. Its total package volume is 25.1 × 19.1 × 1 mm3. It is notable that these electrostatic actuators, with their actuation membranes, acoustic chambers, fluidic channels, and micro valves, are fabricated into a single silicon chip by developing low temperature wafer bonding techniques to protect the polymer structures inside.

scholarly journals Helmholtz resonance in a piezoelectric–hydraulic pump-based hybrid actuator

2010 ◽  
Vol 20 (1) ◽  
pp. 015010 ◽  
Author(s):  
Gi-Woo Kim ◽  
K W Wang
Keyword(s):  
Hydraulic Pump ◽  
Helmholtz Resonance ◽  
Hybrid Actuator

Research on effect of Helmholtz resonance on the stability of reactor coolant flow measurement

2020 ◽  
Vol 364 ◽  
pp. 110644
Author(s):  
Ying Zheng ◽  
Huaqing Wan ◽  
Hai Zou ◽  
Liang Li ◽  
Fengyin Xiong ◽  
...  
Keyword(s):  
Flow Measurement ◽  
Coolant Flow ◽  
Helmholtz Resonance ◽  
Reactor Coolant ◽  
The Stability

Is Helmholtz Resonance a Problem for Micro-jet Actuators?

2007 ◽  
Vol 78 (3-4) ◽  
pp. 205-222 ◽  
Author(s):  
Duncan A. Lockerby ◽  
Peter W. Carpenter ◽  
Christopher Davies
Keyword(s):  
Helmholtz Resonance ◽  
Jet Actuators

Studies of helmholtz resonance in a swirl burner/furnace system

1996 ◽  
Vol 26 (2) ◽  
pp. 3355-3362 ◽  
Author(s):  
D. Froud ◽  
A. Beale ◽  
T. O'Doherty ◽  
N. Syred
Keyword(s):  
Swirl Burner ◽  
Helmholtz Resonance

scholarly journals Relationship between Helmholtz-resonance absorption and panel-type absorption in finite flexible microperforated-panel absorbers

2010 ◽  
Vol 71 (4) ◽  
pp. 315-320 ◽  
Author(s):  
Masahiro Toyoda ◽  
Rui Lin Mu ◽  
Daiji Takahashi
Keyword(s):  
Resonance Absorption ◽  
Helmholtz Resonance ◽  
Panel Type
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