• Title/Summary/Keyword: Surface pressure

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Numerical Analysis on the Deformation of Free Surface of Magnetic Fluid (자성유체의 자유표면의 변형에 관한 수치해석)

  • Nam S.W.;Kamlyama S.
    • 한국전산유체공학회:학술대회논문집
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    • 1995.10a
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    • pp.132-137
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    • 1995
  • Numerical analysis is conducted on the deformation of free surface of magnetic fluid. Steady magnetic fields are induced by a circular current loop. Governing equations of magnetic fields are solved by using the concept of vector potential. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. The deformations of free surface of magnetic fluid are qualitatively clarified. And, the patterns of steady non-uniform magnetic fields induced by a circular current loop are quantitatively presented.

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Estimation of surface tension of liquid alloys under different oxygen partial pressure

  • Min, Sun-Gi;Lee, Jun-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2008.11a
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    • pp.101-101
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    • 2008
  • The effect of oxygen partial pressure on the surface tension data of liquid alloys was investigated by means of comparing the calculated data and the measured one. Two binary alloy systems were chosen to observe the dependence of oxygen adsorption behavior on different oxygen partial pressures. It was found that the difference between the computed values and the experimental of the surface tension was within the range of maximum 10%.

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The Effect of Molding Conditions on the Surface Gloss of HIPS Molding (HIPS 성형품에서 성형조건이 표면 광택에 미치는 영향)

  • Jeong, Y.D.;Lee, M.H.
    • Journal of Power System Engineering
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    • v.4 no.3
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    • pp.81-85
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    • 2000
  • The surface gloss of the injection molded part is one of the most significant point for evaluation the quality of products appearance. The effects of molding condition on the gloss of HIPS(High Impact Poly Styrene) molded part were investigated in this work. The measurements of gloss on the surface of molded part were carried out with different melt temperature, mold temperature, injection pressure and holding pressure. We observed the result of HIPS gloss compared with our's previous ABS study. The more melt and mold temperature increased, the brighter the gloss increase. Holding and injection pressure had little effect on the gloss. The gloss was effected in order of melt temperature, mold temperature, injection pressure, holding pressure.

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Partial-EHL Analysis of Wheel Bearing for a Vehicle (자동차용 휠 베어링의 부분탄성유체윤활 해석)

  • Kim Dong-Won;Lee Sang-Don;Cho Yong-Joo
    • Tribology and Lubricants
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    • v.21 no.6
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    • pp.289-295
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    • 2005
  • Most machine element, such as gears and bearings, are operated in the mixed lubrication region. Contact between two asperities has an effect on machine life by increasing local pressure. To estimate fatigue life exactly, asperity contact should be considered as a factor of fatigue life because this happening produce friction, abrasion and make flash temperature. In this paper, asperity contact is considered as a result of film breakdown when lubricant pressure is not enough to separate two asperities. Contact pressure is calculated to asperity overlap region and added to lubricant pressure. For this model, numerical procedure is introduced and the result on surface roughness and velocity for wheel bearing is presented. Results of EHL analysis for wheel bearing show that asperity contact is occurred at the edge ofEHL conjunction where has a insufficient lubricant pressure to separate two surface.

The Study on Emission Spectrum Characteristics of Atmosphere Pressure Plasma (상압 플라즈마의 광 방출 스펙트럼 특성조사에 관한 연구)

  • Park, Sung-Jin
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.2
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    • pp.77-83
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    • 2013
  • In this study, we aimed to determine the optical properties of the plasma used for the dry cleaning method. The optical properties of the atmospheric pressure plasma device were measured through the degree of ionization of hydrogen or nitrogen gas by ionized atmospheric gas. The degree of ionization of hydrogen or nitrogen is closely associated with surface modification. We observed through our experiments that argon gas, an atmospheric gas, caused an increase in the ionization of nitrogen gas, which has similar ionization energy. This type of increase in nitrogen gas ions is believed to affect surface modification. The results of our study show that the pressure of argon gas and the partial pressure of argon and nitrogen gases lead to different results. This important result shows that argon ions can affect the ionization of nitrogen gas.

Radiated Sound from Compliant and Viscoelastic Plates in a Turbulent Boundary Layer (난류 경계층에서 컴플라이언트 코팅과 점탄성 벽면의 방사 소음에 관한 실험적 연구)

  • Lee Seungbae;Lee Chang-Jun;Kwon O-Sup;Jeon Woo-Pyung
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.779-782
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    • 2002
  • We examine the problem in which porous/viscoelastic compliant thin plates are subject to pressure fluctuations under transitional or turbulent boundary layer. Measurements are presented of the frequency spectra of the near-field pressure and radiated sound by compliant surface. A porous plate consisting of 5mm thick, open-cell foam with fabric covering and a viscoelastic painted plate of 1mm thick over an acoustic board of 4m thick were placed over a rigid surface in an anechoic wind tunnel. Streamwise velocity and wall pressure measurements were shown to highly attenuate the convective wall pressure energy when the convective wavenumber ($k_{ch}$) was 3.0 or more. The sound source localization on the compliant walls is applied to the measurement of radiated sound by using an acoustic mirror system.

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Stress Intensity Factor Analysis of Nozzle Considering Pressure and Heat Transfer on Crack Face (균열면에 작용하는 내압과 열전달의 영향을 고려한 노즐부의 응력확대계수 해석)

  • Jeong, Min-Jung;Kim, Yeong-Jin;Gang, Gi-Ju;Beom, Hyeon-Gyu;Pyo, Chang-Ryul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9 s.180
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    • pp.2252-2258
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    • 2000
  • In order to investigate the effect of nozzle on stress concentration in pressure vessels, three dimensional finite element analyses were performed. The results were compared with those for corresponding two dimensional axisymmetric finite element analyses. A three dimensional finite element model with a surface crack was also designed to evaluate the effect of internal pressure and heat transfer on crack face, and the resulting stress intensity factors from the finite element analyses were compared with those for ASME Sec. XI and Raju-Newman's stress intensity factor solution. As a result, the validity of currently available stress intensity factor solutions for a surface crack was reviewed in the presence of geometrical complexity, heat transfer and internal pressure.

Radiated Sound from Compliant and Viscoelastic Plates in a Turbulent Boundary Layer (난류 경계층에서 컴플라이언트 코팅된 벽면과 점탄성 벽면의 방사 소음에 관한 실험적 연구)

  • Lee, Chang-Jun;Lee, Seung-Bae;Kwon, O-Sup;Jun, Woo-Pyung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.3
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    • pp.294-301
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    • 2003
  • We examine a problem in which porous/viscoelastic compliant thin plates are subject to pressure fluctuations under transitional or turbulent boundary layer. Measurements are presented of the frequency spectra of the near-field pressure and radiated sound by compliant surface. A porous plate consisting of 5mm thick. open-cell foam with fabric covering and a viscoelastic-painted plate of 1mm thick over an acoustic board of 4mm thick were placed over a rigid surface in an anechoic wind tunnel. Streamwise velocity and wall pressure measurements were shown to highly attenuate the convective wall pressure energy when the convective wavenumber (k$_{c}$h) was 3.0 or more. The sound source localization on the compliant walls is applied to the measurement of radiated sound by using an acoustic mirror system.

Approximate Optimization of High-speed Train Shape and Tunnel Condition to Reduce the Micro-pressure Wave (미기압파 저감을 위한 고속전철 열차-터널 조건의 근사최적설계)

  • Kim, Jung-Hui;Lee, Jong-Soo;Kwon, Hyeok-Bin
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1023-1028
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    • 2004
  • A micro-pressure wave is generated by the high-speed train which enters a tunnel, and it causes explosive noise and vibration at the exit. It is known that train speed, train-tunnel area ratio, nose slenderness and nose shape mainly influence on generating micro-pressure wave. So it is required to minimize it by searching optimal values of such train shape factors and tunnel condition. In this study, response surface model, one of approximation models, is used to perform optimization effectively and analyze sensitivity of design variables. Owen's randomized orthogonal array and D-optimal Design are used to construct response surface model. In order to increase accuracy of model, stepwise regression is selected. Finally SQP(Sequential Quadratic Programming) optimization algorithm is used to minimize the maximum micro-pressure wave by using built approximation model.

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Partial-EHL Analysis of wheel Bearing (휠 베어링의 부분탄성유체윤활 해석)

  • Kim D.W.;Lee S.D.;Cho Y.J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.616-621
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    • 2005
  • Most machine element, such as gears and bearings, are operated in the mixed lubrication region. Contact between two asperities has an effect on machine life by increasing local pressure. To estimate fatigue lift exactly, asperity contact should be considered as a factor of fatigue liff because this happening produce friction, abrasion and make flash temperature. In this paper, asperity contact is considered as a result of film breakdown when lubricant pressure is not enough to separate two asperities. Contact pressure is calculated to asperity overlap region and added to lubricant pressure. For this model, numerical procedure is introduced and the result on surface roughness and velocity for wheel bearing is presented. Results of EHL analysis for wheel bearing show that asperity contact is occurred at the edge of EHL conjunction where has a insufficient lubricant pressure to separate two surface.

  • PDF