• Title/Summary/Keyword: Acoustic Field Visualization

Search Result 27, Processing Time 0.024 seconds

Development of sound field visualization technique using digital image processing (디지털화상처리에 의한 음장의 가시화기법개발에 관한 연구)

  • 도덕희;김동혁;강동림
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.24 no.4
    • /
    • pp.515-525
    • /
    • 2000
  • A new acoustic field visualization technique is introduced in this study. Small particles of which density is small enough to follow up the air used for the noise field visualization. In order to quantify the noise, PIV(Particle Imaging Velocimetry) has been constructed. When the driving frequency is in the vicinity of the resonance frequency of the simplified 2-dimensional muffler system, an acoustic streaming is shown and of which velocity distribution is obtained through PIV technique. It is experimentally proved that the present technique is able to visualize and quantify the acoustic fields.

  • PDF

Real time measurement of an acoustic stream by a visualization technique, PIV (PIV(Particle Imaging Velocimetry)에 의한 음향류의 실시간 가시화 계측)

  • 도덕희
    • Proceedings of the Acoustical Society of Korea Conference
    • /
    • 1998.06c
    • /
    • pp.239-242
    • /
    • 1998
  • A new real time sound field visualization technique is introduced in this study using PIV(Particle Imaging Velocimetry) technique. Small particles of which density is small enough to follow up the air flow are used for sound visualization. When the driving frequency is in the vicinity of the resonance frequency of the simplified 2-dimensional muffler system, an acoustic streaming is shown and of which velocity distribution is obtained through PIV technique. It is experimentally proved that the present technique is able to visualize and quantify the sound field's energy flow.

  • PDF

Sound Visualization Gallery: A means to express sound field in space and time (소리를 시각화하는 다양한 방법)

  • Choi, Joung-Woo;Kim, Yang-Hann
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2005.11a
    • /
    • pp.629-632
    • /
    • 2005
  • What does sound look like if we can see it? It might depend on the acoustic variables we want to see. In this article, we propose various ways to visualize or express sound field in much more intuitive manner. In particular, new visualization schemes that can effectively visualize sound intensity and 3D pressure field are proposed. This allows us to represent sound pressure, particle velocity and acoustic conductance at the same time, even in three-dimensional coordinate. Visualization examples corresponding to the proposed techniques show that we can successfully transfer the meaning of physical variable to visual space.

  • PDF

Review of the Improved Moving Frame Acoustic Holography and Its Application to the Visualization of Moving Noise Sources (개선된 이동 프레임 음향 홀로그래피 방법과 이동 음원의 방사 소음의 가시화에 대한 응용)

  • 박순홍;김양한
    • Journal of KSNVE
    • /
    • v.10 no.4
    • /
    • pp.669-678
    • /
    • 2000
  • This paper reviews the improved moving frame acoustic holography (MFAH) method and its application. Moving frame acoustic holography was originally proposed to increase the aperture size and the spatial resolution of hologram by using a moving line array of microphones. The hologram of scanned plane can be obtained by assuming the sound field to be product of spatial and temporal information. Although conventional MFAH was only applied to sinusoidal signals, it allows us to visualize the noise generated by moving noise sources by employing a vertical line array of microphones affixed to the ground. However, the sound field generated by moving sources becomes different from that of stationary ones due to the movement of the sources. Firstly, this paper introduces the effect of moving noise sources on the obtained hologram by MFAH and the applicability of MFAH to the visualization of moving sources. Secondly, this paper also reviews improved MFAH that can visualize a coherent narrow band noise and a pass-by noise. The practical applicability of the improved MFAH was demonstrated by visualizing tire noise during a pass-by test.

  • PDF

Enhancement of Ultrasonic Sonoluminescence Image Using Digital Image Processing (디지털 영상처리를 이용한 초음파 소노루미네센스 이미지 개선)

  • Kim, Jung-Soon;Jo, Mi-Sun;Mun, Kwan-Ho;Ha, Kang-Lyeol;Jun, Byung-Doo;Kim, Moo-Joon
    • The Journal of the Acoustical Society of Korea
    • /
    • v.26 no.8
    • /
    • pp.409-414
    • /
    • 2007
  • In spite of many studies of the acoustic field visualization by using sonoluminescence phenomena, the visualization method has not been used widely because it needs high acoustic intensity to get the luminescence intensity enough to observe. Recently, the digital camera with high resolution and big memory makes it possible to get the digital image data even though the brightness of the image is too weak to observe with naked eyes. In this study we investigated the variation of sonoluminescence intensity with the acoustic intensity from an ultrasonic transducer. From this result, the inverse function, which makes the tendency of the variation to linear, was obtained. Using the order of the inverse function, we can expect a matching function. Applying the matching function to digital image data, the distribution of the histogram could be controlled appropriately and the image from relatively weak acoustic intensity could be enhanced by the method.

Size-based separation of microscale droplets by surface acoustic wave-induced acoustic radiation force (표면파 유도 음향방사력을 이용한 미세액적의 크기 선별)

  • Mushtaq, Ali;Beomseok, Cha;Muhammad, Soban Khan;Hyunwoo, Jeon;Song Ha, Lee;Woohyuk, Kim;Jeongu, Ko;Jinsoo, Park
    • Journal of the Korean Society of Visualization
    • /
    • v.20 no.3
    • /
    • pp.19-26
    • /
    • 2022
  • In droplet microfluidics, precise droplet manipulation is required in numerous applications. This study presents ultrasonic surface acoustic wave (USAW)-based microfluidic device for label-free droplet separation based on size. The proposed device is composed of a slanted-finger interdigital transducer on a piezoelectric substrate and a polydimethylsiloxane microchannel placed on the substrate. The microchannel is aligned in the cross-type configuration where the USAWs propagate in a perpendicular direction to the flow in the microchannel. When droplets are exposed to an acoustic field, they experience the USAW-induced acoustic radiation force (ARF), whose magnitude varies depending on the droplet size. We modeled the USAW-induced ARF based on ray acoustics and conducted a series of experiments to separate different-sized droplets. We found that the experimental results were in good agreement with the theoretical estimation. We believe that the proposed method will serve as a promising tool for size-based droplet separation in a label-free manner.

Visualization of Multiple Incoherent Sources Using Nearfield Acoustic Holography (음향 홀로그래피를 이용한 다수의 완전 비상관 소음원들의 가시화)

  • 남경욱;김양한
    • Journal of KSNVE
    • /
    • v.9 no.5
    • /
    • pp.922-927
    • /
    • 1999
  • The objective of this paper is to obtain the contribution of each source to the spectrum of pressure, when there are multiple incoherent sources in near-field acoustic holography. For this objective, we have to obtain signals very coherent to the input signals of the sources. To obtain the very coherent signals, many people have measured pressure signals in the vincinity of the sources. However, it is sometimes difficult to locate microphones near to the sources so that the signals are very coherent to the input signals. This paper proposed a method to obtain the very coherent signals by near-field acoustic holography. Therefore, the proposed method does not require the measurement of pressure near to each source. Simulation results for two incoherent monopole sources showed the possibility of the proposed method.

  • PDF

Effect of Ultrasonic Frequency on the Atomization Characteristics of Single Water Droplet in an Acoustic Levitation Field (음향 부양장(acoustic levitation field)에서 초음파 주파수(ultrasonic frequency)에 따른 단일 액적의 미립화 특성)

  • Suh, Hyun Kyu
    • Journal of ILASS-Korea
    • /
    • v.18 no.3
    • /
    • pp.126-131
    • /
    • 2013
  • This paper describes the effect of ultrasonic frequency(f) on the atomization and deformation characteristics of single water droplet in an acoustic levitation field. To achieve this, the ultrasonic levitator that can control sound pressure and velocity amplitude by changing frequency was installed, and visualization of single water droplet was conducted with high resolution ICCD and CCD camera. At the same time, atomization and deformation characteristics of single water droplet was studied in terms of normalized droplet diameter($d/d_0$), droplet diameter(d) variation and droplet volume(V) variation under different ultrasonic frequency(f) conditions. It was revealed that increase of ultrasonic frequency reduces the droplet diameter. Therefore, it is able to levitate with low sound pressure level. It also induces the wide oscillation range, large diameter and volume variation of water droplet. In conclusion, the increase of ultrasonic frequency(f) can enhance the atomization performance of single water droplet.

Feasibility Study on Detection of Defective Elements in a Linear Phased Array Transducer through Ultrasonic Field Analysis and Visualization (초음파 음장해석 및 가시화를 통한 선형 위상차배열 트랜스듀서의 결함요소 검출 가능성 연구)

  • Choi, Kwang-Yoon;Yang, Jeong-Won;Ha, Kang-Lyeol;Kim, Moo-Joon;Kim, Jung-Soon;Lee, Chae-Bong
    • The Journal of the Acoustical Society of Korea
    • /
    • v.28 no.5
    • /
    • pp.416-423
    • /
    • 2009
  • The ultrasonic pressure fields for the 3 MHz linear phased array transducer with sixteen piezoelectric elements of which one may not be operated by defect were simulated theoretically and measured experimentally using a visualization system of the Schlieren method. The simulation results for steering angles of $0^{\circ}$ and $30^{\circ}$ show that the side-lobe patterns of the transducer including a defective element is quite different from the transducer with all normal elements, and those patterns are in good agreement with the results of visualization. It is shown that the defective elements in a linear array transducer can be detected by comparison of the simulated and the visualized side-lobe patterns in two dimensional acoustic fields.

Visualization of Sound Field of Plate-Cavity Coupled System by Experimental Method (실험적 방법에 의한 평판-공동 연성계의 음장 가시화)

  • 김시문;김양한
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1997.04a
    • /
    • pp.662-668
    • /
    • 1997
  • Since the structural impedance is much greater than that of medium in the most cases, we often assume that the structure is rigid and that the structural vibration is independent of medium, i.e. we usually calculate the vibration of the structure first, and then obtain the radiation sound from it. This assumption is no longer satisfied when the structural stiffness is small or the fluid impedance is comparable to it. This situation often happens in underwater acoustics. Although many researchers have studied about structural-fluid coupling, we have difficulties in solving the problem analytically. Therefore the numerical method using powerful computation leads us to obtain the various coupling problem. To understand the physical coupling phenomena, visualization of sound field by a geometrically simple system(plate-cavity coupled system) is performed experimentally. Acoustic holographic method is used to estimate sound field.

  • PDF