• Title/Summary/Keyword: Static Characteristics

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Pressure Loss and Heat Transfer Characteristics of Heat Exchanger Using Static Mixing Technology (정적혼합기술 응용 열교환기의 압력손실 및 열전달 특성)

  • Park Sang-Kyoo;Yang Hei-Cheon;Jeon Jun-Chul
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.1
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    • pp.65-72
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    • 2006
  • Heat transfer augmentation in heat exchangers has received much attention in recent years, mainly due to energy efficiency and environmental considerations. Many active and Passive techniques are currently being employed in heat exchangers, with some inserts providing a cost-effective and efficient means of augmenting heat transfer. The Purpose of this paper is to determine the pressure loss and heat transfer characteristics of a heat exchanger using static mixing technology. Experimental measurements were taken on two set-ups: a single tube heat exchanger and a shell-tube heat exchanger with two static mixing inserts. It was concluded that the static mixing inserts resulted in an increase in the pressure loss and heat transfer characteristics as can be expected.

Static Deformation Analysis and Dynamic Characteristics Predicton of Compressed Rubber Materials (압축된 고무재료의 정적 변형 해석과 동특성 예측)

  • 김국원;임종락;손희기;안태길
    • Journal of KSNVE
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    • v.9 no.3
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    • pp.472-476
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    • 1999
  • The effect of static preload on the dynamic properties of rubber materials is rather important, especially when good isolation characteristics are required at high frequencies. However, there are still few papers for dynamic characteristics of compressed rubber components. It was demonstrated in reference (4) that for bonded rubber material of a cylindrical shape, a simplified theory equation between linear dynamic and nonlinear static behavior of rubber material was useful to predict their combined effects. This paper presents the second part of the study. It is confirmed that for the compressed rubber material, the stress can be factored into a function of frequency and a function of strain(stretch). The finite element methodis applied to analyze non-linear large deformation of rubber material and its results are compared with those of a simplified theory equation. The predicted dynamic material properties based on non-linear static finite element analyses have a good agreement of experimental results and those based on simplified theory equation.

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The Effect of Water Contact Angles of the Fin Surfaces of the Fin-and-Tube Heat Exchangers on the Water Hold-up (핀-관 열교환기에서의 핀의 물 접촉각이 응축잔수량에 미치는 영향)

  • 신종민;이남교;한성주;하삼철
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.6
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    • pp.490-496
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    • 2001
  • An experimental study on the behavior of the water hold-up by condensation of a fin-and-tube heat exchanger with regard to the surface characteristics, i.e., contact angle, was conducted. The static and dynamic contact angles were measured, and condensation experiments were conducted. Flow patterns on the fins with different surface characteristics were visualized. Results showed that the static contact angle is proportional to the dynamic contact angle within the range of this study. The water hold-up of the heat exchanger increases as the static or dynamic contact angle of its surfaces increases. Existence of transition of flow patterns was found as the static or dynamic angle increase. Due to the transition in the flow patterns, changes in the gradient of the water hold-up is occurred around the static angle of 8$0^{\circ}C$.

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Development of Radial Fin Static Mixers for Emulsion Oil (이멀션유용 방사상 핀 정적믹서 개발)

  • 김기성;박상규
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.4
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    • pp.904-911
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    • 2001
  • The fuels of water-in-oil emulsion have a potential of reducing PM(Particulate Matter) and NOx emissions, and increasing combustion efficiency in the furnaces and the burners. For making the most of the beneficial of the secondary atomization due to the microexplosion, the water droplets distributed in the oil must have the optimal sizes. The purpose of this paper is to investigate the water droplet size distribution characteristics of the different types of the static mixers. For analysis the size distribution characteristics efficiently, image analysis system wes constructed and an appropriate image processing algorithm was developed. Two kinds of static mixers: Kenics type and RF type, were tested. As a results, RF type static mixer shows a better characteristics in the mean drop size, particularly in the condition of high water content.

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Static load test and dynamic characteristics analysis of bogie and body structures of an oil tank (유조화차의 대차 및 구조체 하중시험과 동특성 해석 연구)

  • 홍재성;함영삼;백영남;오택열;김길동
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.780-783
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    • 2003
  • In this study, As The Tae Yang Metal company manufactured oil tank inserts welding structure bogie, it is Contributed in stability security of freight car of oil tank through static load test, dynamic characteristics analysis. vibration performance test etc. to verify intensity of bogie frame & body structure

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EFFECT OF MISALIGNMENT ON THE STATIC CHARACTERISTICS OF 3-LOBE proceeding BEARING

  • Strzelecki, S.;Radulski, W.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.95-96
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    • 2002
  • The operation of proceeding bearing in the conditions of misaligned axis of proceeding and bush leads to the load concentration on the bearing edges causing further mixed lubrication conditions, unstable operation and intensive wear of mating parts. For the design process of proceeding bearing the knowledge of static characteristics determined from the oil film pressure and temperature distribution is very important. For the 3-lobe proceeding bearing, the pressure, temperature and viscosity fields, load capacity, minimum oil film thickness, power loss, oil flow and maximum oil film temperature have been determined by iterative solution of the Reynolds', energy and viscosity equations. The paper introduces the results of theoretical investigations of static characteristics of 3-lobe proceeding bearing operating at misaligned axis of proceeding and bush. An effect of misalignment ratio, length to diameter ratio of the proceeding bearing, the lobe clearance ratio on the static characteristics was investigated. Laminar, adiabatic model of oil film for the solution of Reynolds, energy and viscosity equations was applied.

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NUMERICAL INVESTIGATION ON STATIC STIFFNESS CHARACTERISTICS OF POROUS AIR BEARING CONSIDERING ROUGHNESS EFFECTS (조도효과를 고려한 다공질 공기베어링의 정강성 특성에 관한 수치해석 연구)

  • Gwon, H.R.;Lee, S.H.;Lee, J.E.
    • Journal of computational fluids engineering
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    • v.13 no.2
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    • pp.62-67
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    • 2008
  • This study aims to investigate numerically the static stiffness characteristics of porous air bearing and to estimate appropriate permeability values of porous medium. In particular, a new roughness model is proposed and implemented into the commercial CFD code (FLUENT Ver. 6.2) by using C language based user subroutine. The predicted results are extensively compared with experimental data. The roughness model is also validated through comparison with the results from open literature. It is found that the predictions for static stiffness are in good agreement with experimental data. Therefore, the suggested model based on the roughness Reynolds number can be used in studying the stiffness characteristics of porous air bearing effectively. In addition, numerical simulations of various diameter size and conditions are conducted. According the results, it is expected that the static stiffness of porous air bearing has the non-linear characteristics.

Compromise Optimal Design using Control-based Analysis of Hypersonic Vehicles

  • Liu, Yanbin;bing, Hua
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.2
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    • pp.137-147
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    • 2015
  • Hypersonic vehicles exhibit distinct dynamic and static characteristics, such as unstable dynamics, strict altitude angle limitation, large control bandwidth, and unconventional system sensitivity. In this study, compromise relations between the dynamic features and static performances for hypersonic vehicles are investigated. A compromise optimal design for hypersonic vehicles is discussed. A parametric model for analyzing the dynamic and static characteristics is established, and then the optimal performance indices are provided according to the different design goals. A compromise optimization method to balance the dynamic and static characteristics is also discussed. The feasibility of this method for hypersonic vehicles is demonstrated.

Development of a Static and Dynamic Characteristics Analysis System for Machine -Tool Spindle Systems with 3 Lobe Sliding Bearings (3원호 미끄럼 베어링을 적용한 공작기계 주축계의 정적 및 동적 특성 해석시스템 개발)

  • 조재완
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.4
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    • pp.99-107
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    • 2000
  • In this study, a static and dynamic characteristics analysis system for machine tool spindle systems with 3 lobe sliding bearing is developed based on Timoshenko theory, finite element method and windows programming techniques. And the characteristics value of 3 lobe sliding bearing such as eccentricity ratio, attitude angle, friction coefficient , stiffness coefficients, damping coefficients and so on, are determined by using the thermal equilibrium conditions of spindle systems. Since the developed system has various analysis modules related to static deformation analysis, modal analysis, frequency responses analysis and so on, it can be utilized to perform systematically the design an devaluation process of spindle systems with 3 lobe sliding bearing under windows GUI environment.

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Mixing Characteristics of Static Mixers (스태틱 믹서의 혼합특성)

  • Yang, Hei-Cheon;Park, Sang-Kyoo;Oh, Seung-Won
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1955-1960
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    • 2003
  • Static mixers have found a large range of applications, including blending, reaction, dispersion, heat transfer and mass transfer. All static mixers have in common a straight pipe or transfer tube into which individual elements are inserted to cut, fold, twist and re-combine the mixing fluid. The operations virtually ensure uniformity in composition, concentration, viscosity and temperature. The objective of this study is to perform the experimental investigations of mixing characteristics for three mixing element types. The resulting mixing patterns were recorded with a digital camera. OPTIMAS was used to analysis the visualized images. The results clearly indicated that the mixing characteristics was highly influenced by the mixer types or mixing mode.

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