scholarly journals Shape Oscillation of Bubble(s) in Acoustic Field

2010 ◽  
Author(s):  
Ichiro Ueno ◽  
Keishi Matsumoto ◽  
Atsumi Machida ◽  
Tsuyoshi Hanyu
Keyword(s):  
Acoustic Wave ◽  
Fundamental Frequency ◽  
High Speed ◽  
Pressure Field ◽  
Capillary Tube ◽  
Gradual Transition ◽  
Distinct Mode ◽  
Shape Oscillation ◽  
Volume Oscillation ◽  
Axisymmetric Shape

We focus on dynamics of multiple air bubbles exposed to acoustic pressure field while ascending in water. The bubbles are injected into the pool filled with water from a vertical capillary tube, and then the acoustic wave of designated frequency is applied toward the bubbles. The frequency of the acoustic wave is varied from 0.5 to 20 kHz. Volume and shape oscillations of the bubbles are captured by a high-speed camera at frame rates up to 40000 fps with a back-lighting system. Through this system, we succeed in capturing the dynamics of the axisymmetric shape oscillation with a distinct mode number; the bubble exhibits the volume oscillation first with a fundamental frequency f0, and then the gradual transition to the shape oscillation with a fundamental frequency fnm takes place. We evaluate the correlation through the careful observations between the f0 and fnm as f0 ∼ 2.1fnm, which brings almost perfectly confirmation of the prediction through the preceding theoretical works. We also indicate the criterion of the excitation of the shape oscillation by varying the frequencies of the adding pressure field.

The dynamic amplification factors for continuous beam bridges along high-speed railways

2021 ◽  
pp. 136943322110032
Author(s):  
Lin Ma ◽  
Wei Zhang ◽  
Steve C.S. Cai ◽  
Shaofan Li
Keyword(s):  
Fundamental Frequency ◽  
High Speed ◽  
Continuous Beam ◽  
Empirical Formulas ◽  
High Speed Railway ◽  
Amplification Factors ◽  
Girder Bridges ◽  
Continuous Beam Bridge ◽  
Train Speed ◽  
Dynamic Amplification

In this paper, the dynamic amplification factors (DAFs) of high-speed railway continuous girder bridges are studied. The vehicle-bridge interactions (VBIs) of 13 concrete continuous girder bridges with spans ranging from 48 to 130 m are analyzed, the influences of the train speed, the train marshalling and the bridge fundamental frequency on the DAF are investigated, and the DAF design standard for high-speed railway bridges is discussed. The results indicate that for the continuous beam bridge whose fundamental frequency is less than 3.0 Hz, the maximum DAF is no more than 1.15; while for the bridge examples with a fundamental frequency larger than 3.0 Hz, the maximum DAF reaches 1.25 because the resonance occurs at high train speed. The empirical formulas of the DAFs in the Japan Railway Technical Research Institute (JRTRI) code could provide a conservative estimation of the DAFs of high-speed railway continuous bridges.

Application Of Elastic Layers To Register Pressure Field On The Model Surface In Supersonic Flow

2016 ◽  
Vol 11 (1) ◽  
pp. 23-33
Author(s):  
Maxim Golubev ◽  
Andrey Shmakov
Keyword(s):  
Surface Waves ◽  
High Frequency ◽  
High Speed ◽  
Pressure Pulsation ◽  
Pressure Field ◽  
Leading Edge ◽  
Supersonic Wind Tunnel ◽  
Register Pressure ◽  
Elastic Layers ◽  
Sharp Leading Edge

The work presents the results of application of panoramic interferential technique which is based on elastic layers (sensors) usage to obtain pressure distribution on the flat plate having sharp leading edge. Experiments were done in supersonic wind tunnel at Mach number M = 4. Sensitivity and response time are shown to be enough to register pressure pulsation against standing and traveling sensor surface waves. Applying high-frequency image acquiring is demonstrated to make possible to distinguish at visualization images high-speed disturbances propagating in the boundary layer from low-speed surface waves

Propeller Loading-Induced Velocity Field by Means of Unsteady Lifting Surface Theory

1973 ◽  
Vol 17 (03) ◽  
pp. 129-139
Author(s):  
W. R. Jacobs ◽  
S. Tsakonas
Keyword(s):  
Velocity Field ◽  
High Speed ◽  
Pressure Field ◽  
Numerical Procedure ◽  
Nonuniform Flow ◽  
Surface Theory ◽  
Loading Function ◽  
Lifting Surface ◽  
Space Function ◽  
Induced Velocity

An analysis based on the lifting surface theory has been developed for evaluation of the vibratory velocity field induced by the loading of an operating propeller in both uniform and nonuniform inflow fields. The analysis demonstrates that in the case of nonuniform flow the velocity at any field point is made up of a large number of combinations of the frequency constituents of the loading function with those of the space function (propagation or influence function). A numerical procedure has been developed adaptable to a high-speed digital computer (CDC 6600), and the existing program, which evaluates the steady and unsteady propeller loadings, the resulting hydrodynamic forces and moments, and the pressure field, has been extended to include evaluation of the velocity field as well. This program should thus become a highly versatile and useful tool for the ship researcher or designer.

Developmental Outcome Prediction From Acoustic Cry Analysis in Term and Preterm Infants

PEDIATRICS ◽  
1987 ◽  
Vol 80 (4) ◽  
pp. 529-534
Author(s):  
Barry M. Lester
Keyword(s):  
Fundamental Frequency ◽  
High Speed ◽  
Infant Development ◽  
Developmental Outcome ◽  
Term Infants ◽  
Perceptual Performance ◽  
The Mean ◽  
Speed Computer ◽  
Potential Use ◽  
Bayley Scales

It has been suggested that the cry may reflect the neurophysiologic integrity of the infant and relate to later developmental outcome. In this study, the cry was recorded at term conceptional age in 18 preterm and 13 term infants using a standardized procedure and analyzed by high-speed computer. At 18 months of age, a significant number of infants were correctly classified as scoring high or low on the Bayley Scales of Infant Development based on the mean and variability in the fundamental frequency, variability in the first formant, and the amplitude of the cry. At 5 years of age, a significant number of infants were correctly classified on the McCarthy General Cognitive Index and on the verbal, perceptual-performance, and quantitative subscales based on the variability of the fundamental frequency, variability of the first formant, and amplitude and duration of the cry. Although preliminary, this study supports the potential use of the cry as a noninvasive measure to detect developmental outcome in the infant at risk.

Theory and Measurements of the Propeller-Induced Vibratory Pressure Field

1972 ◽  
Vol 16 (02) ◽  
pp. 124-139
Author(s):  
W. R. Jacobs ◽  
J. Mercier ◽  
S. Tsakonas
Keyword(s):  
High Speed ◽  
Pressure Field ◽  
Processing Technique ◽  
Experimental Program ◽  
Signal Processing Technique ◽  
Experimental Procedure ◽  
Surface Theory ◽  
Blade Frequency ◽  
Development Center ◽  
Theoretical Results

A theory has been developed, based on lifting surface theory, for evaluation of the pressure field generated by an operating propeller in a nonuniform inflow field. In addition, an experimental procedure and a signal processing technique for measuring small pressure levels accurately have been established and utilized in an extensive experimental program. Theoretical results obtained by means of a computer program developed for the CDC 6600 high-speed digital computer agree well with those of experiments conducted at Davidson Laboratory and at the Naval Ship Research and Development Center. The difficulty of accurately establishing by measurements the decay of small pressures at points farther than one radius from the propeller precludes the possibility of determining the blade-frequency force exerted on a flat boundary by integrating the measured signatures. In contrast, integration of double the theoretical free-space pressure over the flat boundary appears to be a feasible and meaningful approach.

Manipulation of a Micro Droplet in a Capillary Tube by Using a Flexural Acoustic Wave

2019 ◽  
Vol 69 (7) ◽  
pp. 766-770
Author(s):  
Jae-Sik PARK ◽  
Sung-Hyun KIM ◽  
Min-Hwan LEE ◽  
Eun-Sun KIM ◽  
In-Kag HWANG*
Keyword(s):  
Acoustic Wave ◽  
Capillary Tube
Sign in / Sign up

Export Citation Format

Share Document