• Title/Summary/Keyword: Static pressure distribution

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Effects of Pad Number on the Static Performances of Large Tilting Pad Journal Bearings (패드 수의 변화가 대형 틸팅패드 저어널 베어링의 정특성에 미치는 영향)

  • Kim Sung-Gi;Kang Ji-Hoon;Kim Kyung-Woong
    • Tribology and Lubricants
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    • v.20 no.6
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    • pp.330-336
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    • 2004
  • In this paper, thermohydrodynamic characteristics of large tilting pad journal bearings which have $3\~8$ tilting pads were numerically analyzed. The turbulent lubrication equation and the energy equation were solved. The regime of operation of this bearing is laminar, turbulent and transitional. Also viscosity of working fluid was considered as function of only temperature and inlet pressure build-up was considered. Numerical results for a large tilting pad journal bearing showed pressure distribution, temperature distribution, eccentricity ratio, and friction torque. The effects of pad number on the static performances of a large tilting pad journal bearing are discussed.

Numerical Analysis of Ball Strainer Screen Module Blockage Effects (볼 여과기 스크린 모듈의 단면 폐쇄효과에 관한 수치해석적 연구)

  • Jeong, Gyung-Cheol;Lee, Hae-Soo;Lee, Chi-Woo
    • Journal of Power System Engineering
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    • v.19 no.1
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    • pp.83-89
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    • 2015
  • A ball strainer screen module, which is used for a condenser tube cleaning system, is a critical mechanical component for maintaining condenser cleanliness. Despite of this importance, not many research have been focused on this module because of its relatively low usage. Employing CFD, this study examines the implication of fluid velocity change and blockage ratio on the ball strainer screen velocity and the static pressure distribution. Through this study, the impact of blockage in the space between ball strainer screen modules is verified. Also, it is found that the ranges of non-dimensional velocity distribution and static pressure distribution decrease as blockage ratio becomes smaller.

Development and Application of System for Pressure Distribution Measurement (압력분포 측정용 시스템 개발 및 응용)

  • 김용환;박성하
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.6
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    • pp.134-140
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    • 2003
  • The film sensor is used for measuring pressure distribution at planar area, especially at a small space or gap. The present paper deals with the development of film type sensors and system for pressure distribution measuring. The developed system is consist of (1)film sensor with 40/sup */40 array, (2)PCI interface card with maximum sampling rate of 100㎐, and (3)software for data processing and real-time display. The contact pressure test of wiper blade and front glass of vehicle was performed with wiper blade by 40cm. Generally spring force of wiper arm is designed at 0.7∼1kN. Test results of total force was 9.4N and 7.1N in each driver and passenger toward. The paper suggested possibility for base definition in wiper design. A windshield wiper blade experiment revealed that the system successfully measured the contact force distribution during static state, showing the usefulness of the developed system.

Analysis and Experimental Investigation of Cylindrical Hydrostatic Bearing (진원형 정수압 베어링의 해석 및 실험적 고찰)

  • 문호지;한동철
    • Tribology and Lubricants
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    • v.6 no.1
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    • pp.57-67
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    • 1990
  • For increasing the performance of Machine tools, the improvement of the static and dynamic characteristics of spindle bearing is important. In this paper are the static characteristics, the pressure distribution, friction force and outlet flow rate, and the dynamic characteristics stiffness and damping coefficient, of a cylindrical hydrostatic journal bearing with multi oil pockets are analyzed.

PSP Pressure Field Visualization of an Oblique Impinging Jet (경사충돌제트의 PSP 압력장 가시화)

  • Kang Jong Hoon;Lee Sang Joon
    • 한국가시화정보학회:학술대회논문집
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    • 2004.11a
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    • pp.10-13
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    • 2004
  • The PSP(pressure sensitive paint) technique has recently received a large attention as a new revolutionary optical method to measure absolute pressure distribution on a model surface. The PSP technique can be applied to quantitatively investigate flow structure using a CCD camera and image processing technique. In the static calibration, the luminescent intensity of PSP coatings was measured from 0kPa to 11kPa with 0.5, 1, 2kPa increments. In this study, the low-pressure PSP technique was applied to an oblique impinging jet to measure pressure field variations on the impingement plate with varying angle of an oblique jet. The flow structure over the impingement plate was visualized using a surface tracing method. As a result, the detail pressure field distributions of the oblique low-speed impinging jet were visualized effectively using the PSP technique.

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Improving Vertical Airflow Uniformity Considering the Structures of the Lower Plenum in a Cleanroom (하부 플레넘 구조물 조건을 고려한 클린룸의 편류 개선 방법)

  • Kim, Young-Sub;Ha, Man-Yeong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.1
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    • pp.17-25
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    • 2008
  • To achieve the unidirectional airflow in a cleanroom, we need to predict accurately the static pressure losses at the lower plenum and to control properly the opening pressure ratio of access floor panels based on these pressure losses. At first, the present study proposed a correlation to predict the velocity distribution at the lower plenum, because the accuracy to predict pressure losses at the lower plenum depends on how to calculate the velocity correctly against the inner structures at the lower plenum. In the second place, this study proposed correlations which considered the effect of inner structures such as columns, ducts and equipments at the lower plenum on pressure losses. In order to test the accuracy of these correlations, we compared air flow patterns before regulating the opening ratio of access floor with those after regulating. Results after regulating the opening ratio of access floor show good unidirectional uniform airflow pattern. So the present method can be used as an important tool to control the air flow in a cleanroom.

A Numerical Study on the Off-Design Performance of Three-Dimensional Transonic Centrifugal Compressor Diffusers (3차원 천음속 원심압축기 디퓨저의 탈설계 성능에 관한 수치적 연구)

  • Kim, Sang Dug;Song, Dong Joo
    • 유체기계공업학회:학술대회논문집
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    • 1999.12a
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    • pp.134-140
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    • 1999
  • A three-dimensional CSCM upwind flux difference splitting Navier-stokes code with two-equation turbulence models was developed to predict the transonic flows in centrifugal compressor diffuser. The k-$\epsilon$ model of Abe et al. performed well in predicting the pressure distribution in the shock wave/turbulent boundary-layer interaction. Three turbulence models predicted the similar distribution of static pressure through the diffuser and showed a good agreement with the experimental results. The secondary flows in the corner were predicted well by these turbulence models. The pressure increase before the throat of the diffuser vane is important for the overall pressure recovery. As the mass flow rate increased the blockage decreased at the throat. The pressure coefficient distribution through the diffuser depended on the throat blockage not on the rotational speed of the impeller.

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Socket Pressure Distribution of the Uni-Lateral Trans-Femoral Amputee with a Suction Socket (흡착식 소켓을 착용한 일측 대퇴절단환자의 소켓내부압력분포)

  • Chang, Y.H.;Kim, Y.H.;Yang, G.T.;Lim, S.H.;Mun, M.S.
    • Proceedings of the KOSOMBE Conference
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    • v.1997 no.05
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    • pp.249-252
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    • 1997
  • A study on static and dynamic socket pressure distributions on a trans-femoral amputee with a suction socket was performed in order to assess an optimal socket fitting and function. Even for the amputee's static neutral position, pressure concentrations were observed in the lateral, medial, and posterior planes of the socket. During free walking, a significant movement of pressure concentration areas was observed. Large socket pressure was observed in the lateral, medial-anterior and posterior walls during mid-stance or push-off period. Socket pressure measurement will be one of the good tool to determine the optimal socket-limb interface.

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The Effects of the Upright Body Type Exercise Program on Foot Plantar Pressure of Archers

  • Kim, Dong-Kuk;Lee, Joong-Sook
    • Korean Journal of Applied Biomechanics
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    • v.26 no.3
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    • pp.285-292
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    • 2016
  • Objective: This study collected data on muscle fatigue and ground reaction force during walking to provide a basis for development of custom-fitted outdoor walking shoes. The study analyzed an upright body exercise program using spine stabilization technique to determine the effect on foot plantar pressure in archers, demonstrate the effectiveness of upright body exercise, and develop a new, effective, and efficient training program. Method: A 12-week upright body exercise program was evaluated for the effect on plantar pressure in archers. Ten prize-winning archers (3 men, 7 women) in B metropolitan city, each with ${\geq}10years$ of experience, were given an explanation of the content and purpose of the program, and provided informed consent. Upright body exercise was performed 3 times a week for 12 weeks. A resistive pressure sensor was used to measure foot plantar pressure distribution and analyze quantitative information on variation in postural stability and weight shifting in dynamic balance during shooting, as well as plantar pressure in static balance with the eyes open and closed. Results: There were no significant differences in foot plantar pressure before and after participation in the exercise program. There was no statistically significant difference in foot plantar pressure in static balance with the eyes open or closed, or in foot plantar pressure in dynamic balance during shooting. Conclusion: An upright body exercise program had positive effects on foot plantar pressure in static and dynamic balance in archers by reducing body sway and physical imbalance during shooting and with eyes closed. This program is expected to help archers improve their posture and psychological state, and thereby improve performance.

Wind pressure on a solar updraft tower in a simulated stationary thunderstorm downburst

  • Zhou, Xinping;Wang, Fang;Liu, Chi
    • Wind and Structures
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    • v.15 no.4
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    • pp.331-343
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    • 2012
  • Thunderstorm downbursts are responsible for numerous structural failures around the world. The wind characteristics in thunderstorm downbursts containing vortex rings differ with those in 'traditional' boundary layer winds (BLW). This paper initially performs an unsteady-state simulation of the flow structure in a downburst (modelled as a impinging jet with its diameter being $D_{jet}$) using a computational fluid dynamics (CFD) method, and then analyses the pressure distribution on a solar updraft tower (SUT) in the downburst. The pressure field shows agreement with other previous studies. An additional pair of low-pressure region and high-pressure region is observed due to a second vortex ring, besides a foregoing pair caused by a primary vortex ring. The evolutions of pressure coefficients at five orientations of two representative heights of the SUT in the downburst with time are investigated. Results show that pressure distribution changes over a wide range when the vortices are close to the SUT. Furthermore, the fluctuations of external static pressure distribution for the SUT case 1 (i.e., radial distance from a location to jet center x=$D_{jet}$) with height are more intense due to the down striking of the vortex flow compared to those for the SUT case 2 (x=$2D_{jet}$). The static wind loads at heights z/H higher than 0.3 will be negligible when the vortex ring is far away from the SUT. The inverted wind load cases will occur when vortex is passing through the SUT except on the side faces. This can induce complex dynamic response of the SUT.