• Title, Summary, Keyword: Standing wave

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Generating a Traveling Wave on an Annular Ring (원환판에서의 진행파 구현 실험)

  • Yun, Shin-Il;Cho, Ji-Hyun;Han, Sang-Bo
    • Proceedings of the KSME Conference
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    • pp.607-612
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    • 2001
  • Rotary ultrasonic motors are based on the traveling wave generated by piezo materials attached on the stator. Large scale model of an annular ring was built to understand the fundamental mechanism involved in the rotary ultrasonic motors. Traveling wave on the structure can be generated by superposing two standing waves. Precise matching of the amplitudes and phase shift between two standing waves in time and space is the key to the success of generating a traveling wave.

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Finite Element Analysis on Standing Wave Phenomenon of a Tire Considering Tread Pattern (트레드 패턴을 고려한 타이어의 스탠딩 웨이브 현상에 대한 유한 요소 해석)

  • Kim, Kee-Woon;Jeong, Hyun-Sung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.2
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    • pp.76-83
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    • 2006
  • Each tire has a critical speed at which a standing wave phenomenon occurs along the circumferential direction. If the standing waves are formed, the tire temperature is rapidly increased and it leads to tire failure eventually. As the formation of the standing waves is closely related to the tire stiffness, the effect of the tread pattern needs to be studied numerically. The standing wave phenomenon of a tire model with tread pattern is predicted by an explicit finite element method. The critical speed of the tire with tread pattern is in a good agreement with the experiment and is $15{\sim}20\;km/h$ lower than that of the tire without tread pattern. The effects of the inflation pressure and the vertical load on the critical speed are also investigated by using the tire model with tread pattern.

THE DELTA STANDING WAVE SOLUTION FOR THE LINEAR SCALAR CONSERVATION LAW WITH DISCONTINUOUS COEFFICIENTS USING A SELF-SIMILAR VISCOUS REGULARIZATION

  • LI, XIUMEI;SHEN, CHUN
    • Bulletin of the Korean Mathematical Society
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    • v.52 no.6
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    • pp.1945-1962
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    • 2015
  • This paper is mainly concerned with the formation of delta standing wave for the scalar conservation law with a linear flux function involving discontinuous coefficients by using the self-similar viscosity vanishing method. More precisely, we use the self-similar viscosity to smooth out the discontinuous coefficient such that the existence of approximate viscous solutions to the delta standing wave for the Riemann problem is established and then the convergence to the delta standing wave solution is also obtained when the viscosity parameter tends to zero. In addition, the Riemann problem is also solved with the standard method and the instability of Riemann solutions with respect to the specific small perturbation of initial data is pointed out in some particular situations.

Interacting Effects of an Ultrasonic Standing-wave on the Propagation Behavior and Structural Stabilization of Propane/Air Premixed Flame (프로판/공기 예혼합화염의 전파거동 및 구조안정화에 대한 정상초음파의 간섭효과)

  • Lee, Sang Shin;Seo, Hang Seok;Kim, Jeong Soo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.16 no.6
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    • pp.1-8
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    • 2012
  • An experimental study has been conducted to scrutinize into the influence of ultrasonic standing wave on the propagating behavior and structural stabilization of propane/air premixed flame at various equivalence ratios in half-open rectangular duct. Evolutionary features of the flame fronts are caught by high-speed images, and the variation of flame structure and local flame velocities along the propagation are analyzed. It is revealed that the propagation velocity agitated by the ultrasonic standing wave is greater than that without the agitation: the velocity enhancement diminishes as the equivalence ratio approaches the stoichiometric. Influence of standing wave on the flame overwhelms that of the buoyancy which slants the flame front towards top of the duct, and thus the standing wave contributes to the structural stabilization of propane/air premixed flame.

Effects of the Equivalence Ratio on Propagation Characteristics of CH4-Air Premixed Flame Intervened by an Ultrasonic Standing Wave (정상초음파가 개재하는 CH4-Air 예혼합화염의 전파특성에 대한 당량비의 영향)

  • Seo, Hang Seok;Lee, Sang Shin;Kim, Jeong Soo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.17 no.2
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    • pp.16-23
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    • 2013
  • An experimental study has been conducted to investigate the effects of equivalence ratio on the propagation characteristics of $CH_4$-air premixed flame intervened by an ultrasonic standing wave. A Schlieren photography was used for the flame structure visualization, and the flame propagation behavior was investigated in detail throughout the post-processing analysis. It is found that the structural variation of methane/air premixed flame caused by the intervention of ultrasonic standing wave give rise to the enhancement of combustion reaction and flame propagation velocity. Effectiveness of the standing wave on the flame velocity decreases as the equivalence ratio increases. Larger flame velocity with the standing wave becomes undistinguishable in a specific range of equivalence ratios.

Dynamics of an atomic wave packet in a standing wave quantized field

  • Tak, Jo-Yeong;Won, An-Gyeong
    • Proceedings of the Optical Society of Korea Conference
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    • pp.252-253
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    • 2001
  • The purpose of this work is to investigate the dynamics of an atomic wave packet whose center-of-mass motion is quantized in a resonant standing wave cavity field. The mechanical aspect of the matter-field interaction has been extensively studied In the theme of atomic beam deflection, diffraction, or reflection by a standing-wave field. The effect caused in the behavior of spontaneous emission by the atomic center-of-mass motion, classical and quantized, in a standing wave cavity mode has been studied, and recently the one-atom laser with quantized atomic center-of-mass motion has been investigated. (omitted)

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Propagation Behavior and Structural Variation of C3H8-Air Premixed Flame with Frequency Change in Ultrasonic Standing Wave (정상초음파의 주파수 변화에 따른 C3H8-Air 예혼합화염의 전파거동 및 구조변이)

  • Lee, Sang Shin;Seo, Hang Seok;Kim, Jeong Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.2
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    • pp.173-181
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    • 2014
  • The propagation behavior and structural variation of a premixed propane/air flame with frequency change in an ultrasonic standing wave at various equivalence ratios were experimentally investigated using Schlieren photography and pressure measurement. The propagating flame was observed in high-speed Schlieren images, allowing local flame velocities of the moving front to be analyzed in detail. The study reveals that the distorted flame front and horizontal splitting in the burnt zone are due to the ultrasonic standing wave. Vertical locations of the distortion and horizontal stripes are intimately dependent on the frequency of the ultrasonic standing wave. In addition, the propagation velocity of the flame front bounded by the standing wave is greater than that of the flame front without acoustic excitation. As expected, the influence of the ultrasonic standing wave on premixed-flame propagation becomes more prominent as the frequency increases.

Agitation Effects of an Ultrasonic Standing Wave on the Dynamic Behavior of Methane/Air Premixed Flame (메탄/공기 예혼합화염의 동역학적 거동과 정상초음파의 교반)

  • Seo, Hang-Seok;Lee, Sang-Shin;Kim, Jeong-Soo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.16 no.3
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    • pp.16-23
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    • 2012
  • This study has been conducted to scrutinize agitation effects of an ultrasonic standing wave on the dynamic behavior of methane/air premixed flame. The propagating flame was caught by high-speed Schlieren images, through which local flame velocities of the moving front were analyzed in unprecedent detail. It is revealed that the propagation velocity agitated by the ultrasonic standing wave is greater than that without agitation at the stoichiometric ratio: the velocity enhancement diminishes as the equivalence ratio approaches upper flammability limit or lower flammability limit. Also, vertical locations of the wave-affected frontal distortions do not vary appreciably, unless the propagating-mode characteristics (pressure amplitude and driving frequency) of ultrasonic standing wave were not changed.

Finite Element Analysis of a Particle Manipulation System Using Ultrasonic Standing Wave (정재초음파를 이용한 입자제어 시스템의 유한요소해석)

  • Cho, Seung-Hyun;Park, Jae-Ha;Ahn, Bong-Young;Kim, Ki-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.565-570
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    • 2009
  • Micro particles in fluid can be manipulated by using ultrasonic standing wave since the ultrasound makes particles move by means of its acoustic radiation force. This work concerns the micro particle manipulation system using ultrasonic standing wave which consists of a microchannel, an adaptive layer, a reflector, and an ultrasonic transduer. In the present system, the effects of the structural elements should be carefully considered to comprehend the system and find the optimal operational condition. In this investigation, finite element analysis was employed to analyze the system. Some interesting characteristics on the reflector thickness, the channel width, and the operational frequency were observed. Several experimental results were compared with the analytic results. Consequently, this work solidifies the importance of those system parameters and reveals the possibility of various applications of the particle manipulation using ultrasonic standing wave.

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