• Title/Summary/Keyword: groove depth

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Shape Optimization of A Micromixer with Herringbone Grooves Using Kriging Model (헤링본 미세혼합기의 크리깅 모델을 사용한 최적형상설계)

  • Ansari, Mubashshir Ahmad;Kim, Kwang-Yong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.8
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    • pp.711-717
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    • 2007
  • Shape optimization of a staggered herringbone groove micromixer using three-dimensional Navier-Stokes analysis has been carried using Kriging model. The analysis of the degree of mixing is performed by the calculation of spatial data statistics. The calculation of the variance of the mass fraction at various nodes on a plane in the channel is used to quantify mixing. A numerical optimization technique with Kriging model is applied to optimize the shape of the grooves on a single wall of the channel. Three design variables, namely, the ratio of groove width to groove pitch, the ratio of the groove depth to channel height ratio and the angle of the groove, are selected for optimization. A mixing index is used as the objective function. The results of the optimization show that the mixing is very sensitive to the shape of the groove which can be used in controlling mixing in microdevices.

A Study on the Optimized Design of O-rings for LPG Filling Unit (LPG 충전노즐에 장착된 O-링의 최적설계에 관한 연구)

  • Kim Chung-Kyun;Kim Do-Hyun
    • Journal of the Korean Institute of Gas
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    • v.10 no.3 s.32
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    • pp.34-40
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    • 2006
  • This paper presents the optimized design of O-rings with a rectangular groove and dovetails, which are strongly related on the sealing performance of LPG filling unit. The computed results on the optimal design are analyzed by non-linear MARC finite element program with Taguchi method. O-rings with 4 different groove models are analyzed for 3 different elastomeric materials. The design parameters are given to polymer materials, groove depth, groove width, and diameter of O-rings. The FEM computed results showed that the affection ratios of O-ring diameter and material property are the most influential parameter among the groove width, groove depth, and compression ratio. Thus, this paper recommends model III for a rectangular groove and model IV for a dovetail groove with a given gas supply pressure of 1.764 MPa.

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Improvement of the Lubrication Characteristics of Fuel Injection Pump for Medium-Speed Diesel Engines: Part II - Application of Grooves (연료분사펌프의 윤활 특성 개선: 제2부 - 그루브의 적용)

  • Hong, Sung-Ho;Lee, Bora;Cho, Yongjoo
    • Tribology and Lubricants
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    • v.31 no.5
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    • pp.213-220
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    • 2015
  • This study evaluates the effect of grooves on the stem part of a plunger on the lubrication characteristics of a fuel injection pump (FIP) by using hydrodynamic lubrication analysis. The current study uses the two-dimensional Reynolds equation to evaluate the changes in lubrication characteristics with variations in clearance, viscosity, and grooves for a laminar, incompressible, and unsteady state flow. This study investigates the lubrication characteristics by comparing the dimensionless minimum film thickness or the film parameter, which is the ratio of the minimum film thickness to surface roughness. The analysis method for the groove section differs depending on the depth of the groove. For instance, in the case of a shallow groove, the film thickness equation considers the depth of the groove, while in the case of a deep grove, it considers the flow continuity. The lubrication characteristics of the FIP are more sensitive to changes in the groove width than to changes in other design variables. Moreover, the application of a groove is more effective under low viscosity conditions. The smaller the distance from the edge of the stem part to the first groove in the case of shallow grooves, the better are the lubrication characteristics of the FIP. In contrast, in the case of deep grooves, the lubrication characteristics of the FIP improve as the distance increases. The application of shallow grooves is more effective for improving the lubrication characteristics than the application of deep grooves.

Large eddy simulation of turbulent flows in a grooved channel (홈이 파진 평판 사이 난류유동의 대와동모사 (LES))

  • Yang, Gyeong-Su;Kim, Do-Hyeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.1
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    • pp.34-49
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    • 1998
  • In this study, turbulent flows in a grooved channel are numerically investigated by Large Eddy Simulation (LES). Especially, a parametric study is carried out to study effects of length and depth of a groove on large-scale flow structures. For one test case, comparison of LES results with those of DNS reveals a good agreement even though the number of grid points of LES is only 6.5% of that of DNS. This confirms that LES is a suitable tool for a parametric study of turbulent flows. The subsequent parametric study using LES shows that the large-scale turbulent structures are significantly affected by the geometry of the groove. Especially, when the length of the groove is short such that the recirculation region occupies the entire groove, the turbulent flow in the groove becomes very weak in both mean and fluctuation quantities.

An Analysis of Load Characteristics of Air-Lubricated Herringbone Groove Journal Bearing By Finite Element Method (공기윤활 빗살무늬 저널베어링의 부하특성에 대한 유한요소해석)

  • 박신욱;임윤철
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.11a
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    • pp.353-362
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    • 2000
  • Herringbone groove journal bearing (HGJB) is developed to improve the static and dynamic performances of hydrodynamic journal bearing. In this study, static and dynamic compressible isothermal lubrication problems are analyzed by the finite element method together with the Newton-Raphson iterative procedure. This analysis is introduced for prediction of the static and dynamic characteristics of air lubricated HGJB for various bearing configurations. The bearing load characteristics and dynamic characteristics are dependent on geometric parameters such as asymmetric ratio, groove depth ratio, groove width ratio and groove angle.

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A Study on the Flow around a D-shape Bluff Body with Arc-Groove (Arc-Groove를 가진 D-형상 물체 주위 유동에 관한 연구)

  • Seo, Seong-Ho;Nam, Chung-Do;Lee, Hyoung-Woo;Hong, Cheol-Hyun
    • The KSFM Journal of Fluid Machinery
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    • v.17 no.6
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    • pp.59-63
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    • 2014
  • Object of this study is to see whether the arc-groove on a D-shape bluff body effects the drag reduction or not. To this end, the changes of the boundary layer on the surface of the object, the downstream flow field and wake flow were found by experiments. The experiments are conducted by changing number and depth of the groove, angle of the first groove and Reynolds number(Re). Groove did not effect on the surface in the downstream boundary layer of the object and was minimal impact on the time mean velocity recovery of the wake flow. Also the effects of Groove did not have a significant impact on the structure of the wake and the wake frequency. Therefore it is found that the arc-groove of the drag reduction effect on the D-shape bluff body was smaller.

Nanoscale Processing on Silicon by Tribochemical Reaction

  • Kim, J.;Miyake, S.;Suzuki, K.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.67-68
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    • 2002
  • The properties and mechanism of silicon protuberance and groove processing by diamond tip sliding using atomic force microscope (AFM) in atmosphere were studied. To control the height of protuberance and the depth of groove, the processed height and depth depended on load and diamond tip radius were evaluated. Nanoprotuberances and grooves were fabricated on a silicon surface by approximately 100-nm-radius diamond tip sliding using an atomic force microscope in atmosphere. To clarify the mechanical and chemical properties of these parts processed, changes in the protuberance and groove profiles due to additional diamond tip sliding and potassium hydroxide (KOH) solution etching were evaluated. Processed protuberances were negligibly removed, and processed grooves were easily removed by additional diamond tip sliding. The KOH solution selectively etched the unprocessed silicon area. while the protuberances, grooves and flat surfaces processed by diamond tip sliding were negligibly etched. Three-dimensional nanofabrication is performed in this study by utilizing these mechanic-chemically processed parts as protective etching mask for KOH solution etching.

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Contact Stress Evaluations for the Ball Groove of Weiss Type Constant velocity joint (Weiss형 등속조인트 볼 홈의 접촉응력평가)

  • 김완두;이순복
    • Tribology and Lubricants
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    • v.5 no.2
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    • pp.60-67
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    • 1989
  • For the life prediction and fatigue failure prevention of the constant velocity joint, the maximum equivalent stress and its location in depth from the contact area are essential. These values give the fundamental information to determine the depth of the surface hardening treatment at the contact area. Contact stresses are evaluated at the surface and subsurface of the ball groove of the Weiss type constant velocity joint. The maximum contact pressure and the maximum equivalent stress are obtained. The effects of various parameters such as the radius of ball groove, friction coefficient, and residual stress are studied. The maximum equivalent stress and the maximum contact pressure increase as the radius of the ball grove increases. The location of the maximum equivalent stress moves toward surface as the friction coefficient increases. It was also found that the maximum equivalent stress becomes minimum when the compressire residual stress is about 0.16 times of the maximum contact pressure.

Radial Performances of Spiral-Grooved Spherical Air Bearings (나선홈을 갖는 반구형 공기 베어링의 반경 방향 성능 측정)

  • Park, Keun-Hyung;Choi, Jeong-Hwan;Choi, Woo-Chon;Kim, Kwon-Hee;Woo, Ki-Myung;Kim, Seung-Kon
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.2 s.95
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    • pp.23-30
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    • 1999
  • This paper investigates the radial performance of self-acting spiral-grooved air bearing, used to support small high-speed rotating bodies. Repeatable runout, nonrepeatable runout, stiffness and supporting load are selected as the performance. The clearance between rotor and stator, the stator groove depth, and the rotating speed are chosen as three main parameters affecting the performances. Force application and displacement measurement are done in a noncontact manner, in order not to disturb operation: electromagnetic force is applied to the rotor and gap sensors are used to measure the displacement of the rotor. Experimental results show that repeatable runout decreases as speed, groove depth and clearance decrease. Nonrepeatable runout decreases as clearance decreases, and it has a minimum value at $5.5{\mu}m$ of grove depth and a maximum value at speed of 18.000rpm. Stiffness increases as speed increases and clearance decreases, and has a maximum value around $5.5{\mu}m$ of groove depth. The relationship between force and displacement is linear for small displacement, but becomes nonlinear for large displacement. Supporting load is linearly proportional to the stiffness, and it is a maximum value around $4.75{\mu}m$ of clearance.

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Fabrication of the Micro-structured DVD-RAM Substrates (미세 형상을 갖는 DVD-RAM 기판의 성형에 관한 연구)

  • 문수동
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.04a
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    • pp.167-170
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    • 2000
  • Recently the sub-micron structured substrates of 0.74 ${mu}ell$ track pitch and 800 $\AA$groove depth are required for DVD-RAM and the track pitch is expected to be narrower as the need for the information storage density is getting higher. For the accurate replication of the land-groove structure in the stamper to the plastic substrates it is important to control the injection -compression molding process such that the integrity of the replication for the land-groove structure is maximized. in the present study polycarbonate substrates were fabricated by injection comression molding and the land-groove structure regarded as one of mold temperature and the compression pressure on the integrity of the replication were examined experimentally. An efficient design methodology using the response surface method (RSM) the central composite design(CCD) technique and the analysis-of-variance (ANOVA) was developed to obtain the optimum processing conditions which maximize the integrity of the replication with a limited number of experiments.

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