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Tuesday, August 4, 2020 | History

1 edition of Measurement of bubble properties using a multi-frequency sound field found in the catalog.

Measurement of bubble properties using a multi-frequency sound field

Robert A. Perron

Measurement of bubble properties using a multi-frequency sound field

by Robert A. Perron

  • 192 Want to read
  • 31 Currently reading

Published by Naval Postgraduate School, Available from the National Technical Information Service in Monterey, Calif, Springfield, Va .
Written in English


Edition Notes

ContributionsAtchley, Anthony Armstrong, 1957-
The Physical Object
Pagination52 p.
Number of Pages52
ID Numbers
Open LibraryOL25472095M

The designed structure is fabricated by using a 3D printer and its sound absorption property is verified experimentally by an impedance tube measurement. The results demonstrate that the present approach is simple but effective to broadband sound absorption with .   However, bubbles also passively emit sound at their natural frequency, that is, without being forced by an external sound field. As a bubble detaches from its parent body of gas, it produces an acoustic pulse. This may be due to a sudden compression of the trapped gas as the bubble pinches off (Manasseh et al. ). This “ringing” of the.

by using the sound intensity method. The sound intensity method is suitable when the measurements are carried out in field conditions where the acoustical environment varies. The sound intensity method, for sound power applications, is regarded as less sensitive to background noise than sound pressure measurements. Field Observations of Sound Speed. Knowledge of sound velocity is important to the ASW tactician and physical oceanographer because of the effect that variations in sound velocity have upon acoustic absorption and refraction. Two different devices are in use today for finding the speed of sound in the sea. Bathythermograph.

  Abstract: Measurements of bubble size and distribution in the ocean bubble layer, wind speed, and variation of ocean environment were made continually over a four-day period in an experiment conducted in the South Sea of Korea during September Theoretical background of bubble population model and bubble effects on sound speed indicate that bubble population is a . The method can also be used to determine the level of music in the open field. Due to the dependence of sound waves on the exact listening situation, as detailed in , it is clear that this type of measurement is not suitable to head phone use where only a small space between the head phones and the inner ear is exposed to sound waves.


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Measurement of bubble properties using a multi-frequency sound field by Robert A. Perron Download PDF EPUB FB2

Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection Measurement of bubble properties using a multi-frequency sound field. A problem of continuous interest in underwater sound propagation is the prediction of the scattering properties of bubbles.

Two important parameters in this problem are the bubble's radius and damping coefficient. A method of measuring these parameters, which is a modification of a bubble‐sizing technique developed by V. Newhouse and P. Shankar [J. by: 1. An apparatus was designed, constructed, and tested to measure properties of single bubbles in a fluid by use of a multi-frequency sound field.

The theoretical background on the dual frequency method for obtaining bubble properties such as resonance frequency, rectified diffusion thresholds and rates, rise-time sizing, and damping coefficients are : Robert A. Perron. measure properties of single bubbles in a fluid by use of a multi-frequency sound field.

The theoretical background on the dual frequency method for obtaining bubble properties such as resonance frequency, rectified diffusion thresholds and rates. A new initial field has been derived using the method of matched asymptotics. Measurement of bubble properties using a multi-frequency sound field The results of measurements of bubble.

Measurements of Bubble Properties Using a Multi-Frequency Sound Field. constructed, and tested to measure properties of single bubbles in a fluid by use of a multi-frequency sound field.

The sound field was irregular and the fundamental at driving frequency decreased. Between the bubble clouds completely different sound field properties were found in comparison to those in the cloud where the cavitation activity is high.

In between the sound field pressure amplitude was quite small and no collapses were detected. Measurements of Bubble Properties Using a Multi-Frequency Sound Field. June and tested to measure properties of single bubbles in a fluid by use of a multi-frequency sound field.

The. A single bubble has little impact on the transmission of sound, but an assembly of bubbles introduces significant changes to the acoustic properties of the host medium. When sound traverses a cluster of bubbles, every bubble produces a secondary scattered wave and these waves reinforce in some directions and interfere in others [6], [7.

Such a bubble collapse is known as the Rayleigh collapse. The radial motion of bubble collapse is discussed using the Rayleigh–Plesset equation for bubble pulsation.

Pulsating bubbles exposed to an ultrasound field radiate acoustic waves into the surrounding liquid, giving rise to acoustic cavitation noise. Figure 26 shows a test setup to measure bubble size distribution (and thus the void fraction) using DYNAFLOW's ABS ACOUSTIC BUBBLE (Prabhukumar et.

where c 0 is the speed of sound in pure liquid, c m is the complex sound speed in the fluid with bubbles, a is the bubble radius, ω is the measurement frequency, ω 0 is the natural frequency of a bubble of radius a, δ is the bubble damping that is defined later in and and is a function of both bubble radius a and acoustical frequency ω, and.

Bubble sizes can be determined acoustically on the basis of three types of measurements: scattering or excessive attenuation of the acoustic wave and the changes in sound velocity. As these are frequency dependent phenomena, two kinds of acoustic resonance can be used (Su et al., ): resonance at low frequencies (50 - Hz) at.

In this section, the basic properties of bubble oscillation under dual-frequency acoustic excitation are investigated. For simplicity, we assume ɛ 1 = ɛ more general cases (e.g., two acoustic waves with unequal amplitudes), readers are referred to Section To avoid the effects of resonance (e.g., the strong nonlinear property near the natural frequency of the bubble oscillator), the.

A bubble size with equivalent spherical radius of mm was used over a frequency range of – Hz. The ultimate aim is to develop an acoustic sensor that can measure static pressure and is sensitive to variations as small as a few kPa.

The classical bubble resonance frequency is known to vary with ambient pressure. Audio Books & Poetry Community Audio Computers, Technology and Science Music, Arts & Culture News & Public Affairs Non-English Audio Spirituality & Religion Librivox Free Audiobook Slingsbot & fejimanz's Super Happy Friendship Hour Ciudad Vida Global Connect Catch This Tea EPIC SECONDS RADIO Erik van Mechelen - Essays and Fiction L.I.T.S.O.T.

Bubble size measurements were conducted at the, 1, 15, l scales, spanning an fold range in scale, all in geometrically similar fermenters. For some combinations of agitation and airflow rates, the bubble density was too high to clearly obtain individual bubble diameter measurements.

The hardware and control software of the SCN can be used for scanning the near field of the transducer by using a microphone or velocity sensor.

Near Field Scanner (NFS) The NFS captures the entire sound field at any point in 3D space. The automatic measurement in the near field can be performed in a normal room (non-anechoic) and the software.

Sound-treated rooms usually are designed to attenuate environmental sound and provide a quiet environment within which to conduct measures of audition under earphones.

These sound rooms are not optimal for sound field use. Before sound field measurements are conducted, the acoustic characteristics of test stimuli must be determined within the room. The electrical signals can also be used to measure the characteristics of the sound, such as amplitude and frequency.

Similarly, hydrophones convert sound in water into electrical signals that can be amplified, recorded, played back over loudspeakers, and used to measure the characteristics of the sound.

The PC is also used for analysis of the data and provides, using Dynaflows's software, the sound speed and attenuation as a function of frequency.

The bubble population can be obtained from these measurements by a solution of two Fredholm Integral Equations of the first kind. The sound field is nearly uniform with depth in the upper 50 m with nearly all sound attenuation limited to the upper 2 m at all measured frequencies.

A simple model of bubble trajectories based on the measured float trajectories finds that resonant bubbles at the high-frequency end of the observations (25 kHz) could easily be advected deeper.Chirp acoustic radiation force can be used to evaluate the mechanical properties of tissue since the acoustic intensity is known and bubble size can be accounted for using integrated backscatter.

Therefore, displacement measurements made with minimal standing wave artifacts will directly measure the local elastic properties.