• 제목/요약/키워드: cavity vibration

검색결과 243건 처리시간 0.024초

EFD를 이용한 곡관부 배관계에 발생하는 유체진동 해석 (The Analysis of Piping Vibration by EFD)

  • 배춘희;조철환;양경현;박영필
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.1070-1072
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    • 2003
  • In this paper, Firstly, it is shown that the high vibration source of piping system is the pulsation transmission of pipe line element ,such as, orifice plate, valves and the control valve is a broad band source and the branch wall and the cavity have vortex frequency Secondly, in order to decrese the turbulence vibration of piping system, the practical analysis of piping flow by EFD have been developed and its effectiveness is investigated as applying it at piping system practically.

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공동 공진해석을 이용한 왕복동식 압축기의 기동소음 저감에 관한 연구 (Start-up Noise Reduction of Reciprocating Compressor Using Cavity Resonance Analysis)

  • 김민철;김원진
    • 한국소음진동공학회논문집
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    • 제20권2호
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    • pp.153-159
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    • 2010
  • This work focuses on finding a method to reduce the noise of a hermetic reciprocating compressor during start-up using an acoustical analysis. The noise of compressor during start-up, which is a higher level than that of a normal operating condition, has transient and non-stationary characteristics. The acoustical analysis of compressor cavity is performed to find an effective method to reduce the noise level. In the acoustical analysis, the shape variations of frequency response function in the neighborhood of resonances are tested for three parameters: the height of remained oil, the suction position of refrigerant and the position of driving part. As a conclusion of this result, to reduce the emission noise of compressor during start-up, the height of remained oil should be kept at 16 mm, the refrigerant should be sucked at the cross point of nodal lines of X and Y directional cavity modes, and the driving part should be positioned in the center of cavity.

유체기인 방사소음 저감용 소음기 개념설계 이론 (CONCEPT DESIGN THEORY OF SHOCK ABSORBING MUFFLERS FOR AIR-BORNE NOISE)

  • Kim, Sang-Myeong
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 춘계학술대회논문집
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    • pp.627-632
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    • 2002
  • The paper considers acoustic analysis of the shock absorbing muffler within a rotary compressor. The internal space of the compressor is modelled as a combination of cavities and pipes. A simple one-dimensional impedance approach is used fur the acoustic analysis in the low frequency range, with ignoring the effects of gas flow and temperature gradients that are closely related to power efficiency of the compressor. Using the similarity between the vibration isolator and the shock absorbing muffler, the source strength transmissibility is newly proposed as a performance measure of the muffler and its validity is supported by power analysis. Some Important muffler design rules obtained are; (1) a muffler cavity and its opening throat should be used as a pair, (2) a long thin throat is desirable for high frequency noise isolation, (3) a large muffler cavity should be used with care since it shortens the working frequency range of the muffler. The rules were applied to redesign a compressor muffler currently in use, and a significant improvement was achieved by simply attaching a throat to the outlet holes of the muffler.

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Vibration control performance of particle tuned mass inerter system

  • Zheng Lu;Deyu Yan;Chaojie Zhou;Ruifu Zhang
    • Structural Engineering and Mechanics
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    • 제89권4호
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    • pp.383-397
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    • 2024
  • To improve the vibration control performance and applicability of traditional particle tuned mass damper (PTMD) and realize the significant characteristic of lightweight design, this study proposes a novel particle tuned mass inerter system (PTMIS) by introducing inerter system (IS) to the PTMD. In the study, the motion equation of single degree of freedom (SDOF) structure attached with PTMIS is established first, then the variation law of the system's vibration reduction performance (VRP) is discussed through parameter analysis, and it is compared with the PTMD to analyze its VRP advantages. Finally, its vibration reduction (VR) mechanism from the perspective of core control force and energy analysis is explored, and its cavity relative displacement from the application perspective is analyzed. The results show that the PTMIS can remarkably improve the vibration control effectiveness of the PTMD. The reason is that the inerter can store energy and transfer the energy to the cavity and particles, which further stimulates the interaction between the two parts, thereby improving the nonlinear energy consumption effectiveness. Also, the IS can amplify the damping element's energy dissipation efficiency. In addition, the PTMIS can effectively reduce the working stroke of the PTMD, and through the analysis of the lightweight characteristics of the PTMIS, it is found that its lightweight advantage can reach nearly 100%.

실내 소음제어를 위한 압전지능구조물의 최적 설계 (Optimal Design of a Piezoelectric Smart Structure for Cabin Noise Control)

  • 고범진;이중근;김재환;최승복;정재천
    • 소음진동
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    • 제8권3호
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    • pp.428-434
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    • 1998
  • Optimal design of a piezoelectric smart structure is studied for cabin noise control. A cubic shaped acoustic cavity with a flat plate which covers one side is taken as the problem. The sensor signal is returned to the actuator through a negative gain. The acoustic cavity is modeled using the modal approach which represents the pressure fields in the cavity as a sum of mode shapes of the cavity with unknown coefficients. By using orthogonality of the mode shapes of the cavity, finite element equation for the structure with the influence of the acoustic cavity is derived. The objective function is the average pressure at a certain region, so-called silent zone, in the cavity and the design variables are the locations and sizes of the piezoelectirc actuator and sensor. The optimal design is performed at several frequencies and the results show a remarkable noise reduction. To see the robustness of the optimally designed result, the configuration is used to examine the noise reduction at different frequencies. By adjusting the gain at each frequencies, it is possible to reduce the noise in comparison with the result when the actuator is not activated.

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공기층을 갖는 공조덕트 구조물에서 흡음재의 흡음특성에 관한 연구 (A Study on the Absorption Characteristics of Absorbents in Duct System with the Air Cavity)

  • 김찬묵;김도연;방극호
    • 소음진동
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    • 제10권5호
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    • pp.892-897
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    • 2000
  • In this paper, experimental methods to find acoustic characteristics of acoustically treated air-conditioning duct system are proposed. Existing methods to analyze acoustic properties of duct with absorbent material have dilemma which has to assume the wave in duct to be a plane wave. Under this assumption. applicable frequency limitation makes accurate analysis of practical air-conditioning system impossible. In order to analyze the properties of in-lined treated absorbent with high degree of accuracy, in this experiments the range of exciting frequency of sound source is broadband, which means that source speaker excited higher mode of in-duct sound field. Also, to define the relations of air cavity to the acoustic characteristics, acoustic experiments on ducts with air cavity of different depth are operated. In conclusion, air-cavity makes the absorbing ability of duct improved in low frequency range. Due to the interactions between the air cavity depth and the depth of absorbents, according to depth of cavity, the magnitude of absorption coefficients vs frequencies in specific range is changed. In lower frequency range, the absorption of sound energy by air cavity is more dominant than by absorbent itself, in higher range, the inversion is true.

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