• 제목/요약/키워드: Circular Tubes

검색결과 238건 처리시간 0.023초

튜브형상에 따른 배기가스 재순환 냉각 장치 열전달 성능 평가 (Heat Transfer Analysis of EGR Cooler with Different Tube Shape)

  • 손창현
    • 한국자동차공학회논문집
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    • 제15권5호
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    • pp.112-117
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    • 2007
  • With the Euro-4 regulation coming into effect, the domestic car industry is forced to look for newer options to reduce NOX in the exhaust. EGR(Exhaust Gas Recirculation) Cooler is an effective method for the reduction of NOX form a diesel engine. High efficiency, low pressure loss and compactness are desirable features of an EGR Cooler. The cooling performance of EGR depends on the shape of tubes and the location of the entrance and exit. This paper reports the computational work conducted to estimate the performance of EGR cooler with three different cross section tubes and a triangular spiral tube. Three dimensional computation results show that the triangular tube is more effective than circular and rectangular tube. The most effective geometry is a triangular spiral tube with offset inlet and outlet locations.

Experimental study on partially concrete-filled steel tubular columns

  • Ishizawa, T.;Nakano, T.;Iura, M.
    • Steel and Composite Structures
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    • 제6권1호
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    • pp.55-69
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    • 2006
  • The results of tests conducted on 11 concrete-filled steel tubular columns were reported. Concrete was partially filled in circular steel tubular columns. The primary test parameters were radius and thickness of steel tubes, concrete height, loading patterns and attachment of diaphragm and studs. Concrete strain was measured directly by embedding strain gauges so that the effect of diaphragm on concrete confinement could be investigated. The effects of concrete height and diaphragm on ultimate strength and ductility of steel tubes were investigated. The comparisons of the test results with the existing results for rectangular cross-sections were made on the basis of ultimate strength and ductility of concrete-filled steel tubular columns.

평행류형 마이크로채널 이산화탄소 증발기에서 냉매분배에 관한 연구 (A Study on the Refrigerant Distribution in a Parallel Flow Micro-Channel $CO_2$ Evaporator)

  • 정시영;김대환
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2009년도 하계학술발표대회 논문집
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    • pp.1079-1083
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    • 2009
  • In this study, the distribution of $CO_2$ in an evaporator with 10 parallel micro channel aluminum tubes are experimentally investigated. Each tube has 6 circular micro channels with a diameter of 0.8mm. The tubes are heated with electric resistance wires, and the distribution of $CO_2$ into each tube is investigated by measuring the outer wall temperature. The outer wall temperature was found to be higher at the exit part of the top tube. It is thought that the $CO_2$ vapor at the upper part of the header reduces the mass flow rate of $CO_2$ into the top tube.

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원형관의 내면정밀가공용 순환식 자기입자분사가공 시스템 개발 (Development of Magnetic Abrasive Jet Machining System for Precision Internal Polishing of Circular Tubes)

  • 강윤희
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 1995년도 추계학술대회 논문집
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    • pp.24-29
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    • 1995
  • A recently developed finishing process using rotating magnetic field is known to be very efficient for the finishing of parts such as vacuum tube, sanitary tube, etc., which are difficult to be finished by the conventional finishing methods as they are generally curbed tubes. But, the finishing system using rotating magnetic field have the defect that is the cross section of workpiece only circle because of internal rotating tool. Therefore, new finishing process of the workpieces which cross section are not circle is important and required. magnetic abrasive jet machining is a new concept finishing process. It is the precision internal finishing method using working fluid mixed with magnetic abrasives, which is jetted into the internal surface of tube. And magnetic poles are equipped on external surface of tube. In this study new concept finishing process or, magnetic abrasive jet machining system was developed. machining condition was predicted using simulation and some characteristics of the finishing process was analyzed.

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Explicit/Implicit FEM에 의한 Lower Arm Hydroforming 공정해석 (FE Analysis of Lower Arm Hydroforming by Implicit and Explicit Method)

  • 강영호;김정;장유철;강범수
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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    • pp.783-788
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    • 2000
  • Hydroforming is a method for forming circular tubes. If this technology is to be applied economically, it is essential to have knowledge of the avoidance of failure cases as well as of the behavior of the tube in the tool under the compressive stress and forces that are exerted by the machine. A finite element simulation for manufacturing of lower arm from straight tubes, using the hydroforming method, was performed to investigate the effects of varying process parameters. Explicit method is used to simulate hydroforming in many cases, but that is not included flow rule. And then it needs simulation for implicit method. It was simulated by two methods, implicit and explicit, to compare the result of the hydroforming.

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스티프너로 보강한 콘크리트 충전 원형 강관기둥의 부착응력에 관한 실험적 연구 (An Experimental Study on a Bond Stress in Concrete Filled Circular Steel Tubular Column Strengthened by the Stiffener)

  • 박성무;김성수;김원호;이형석
    • 한국공간구조학회논문집
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    • 제2권2호
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    • pp.51-58
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    • 2002
  • This paper is presented an experimental studies on bond stress between steel and concrete in concrete filled steel tubes. In the actual building frames, vertical dead and live loads on beams are usually transferred to columns by beam-to-column connections. In case when concrete filled steel tubes are used as columns of an actual building frame which has a simple connection, shear forces in the beam ends are not directly transferred to the concrete core but directly to the steel tube. Provided that the bond effect between steel tube and concrete core should not be expected, none of the end shear in the beams would be transferred to the concrete core but only to the steel tube. Therefore, it is important to investigate the bond strength between steel tube and concrete core in the absence of shear connectors.

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유동조건과 내부관 구명형상의 변화에 따른 소음기의 소음저감 특성 (Characteristics of Noise Attenuation with the Variation of Flow Condition and Hole Shape of Perforated Intruding Tues in Muffler)

  • 정진년;김원진;조범례
    • 한국정밀공학회지
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    • 제16권10호
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    • pp.87-93
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    • 1999
  • To propose a useful modelling method for an actual muffler, the noise attenuation effects of muffler was investigated according to the flow condition and the hole shape of tubes. In this work, the finite element method was used to calculate the transmission loss of muffler, The noise attenuation characteristics of four different types of muffler in the hole shape of tubes were compared mutually to find a more simple equivalent model. Analytical results showed that the overall value of transmission loss increases and the peaks of transmission loss curve shift to the low frequency with mean flow for the given muffler, Also the noise attenuation characteristics of the equivalent model having the split holes is almost the same as those of the actual muffler having many circular holes.

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Degradation of buckling capacity of slender concrete-filled double skin steel tubular columns due to interface compliance

  • Cas, Bojan;Schnabl, Simon
    • Structural Engineering and Mechanics
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    • 제82권5호
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    • pp.643-650
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    • 2022
  • In this paper a novel mathematical model and its analytical solution of global buckling behaviour of slender elastic concrete-filled double-skin tubular (CFDST) columns with finite compliance between the steel tubes and a sandwiched concrete core is derived for the first time. The model is capable of investigating the influence of various basic parameters on critical buckling loads of CFDST columns. It is shown that the elastic buckling load of circular and slender CFDST columns is independent on longitudinal contact stiffness, but, on the other hand, it can be considerably dependent on circumferential contact stiffness. The increasing of the circumferential contact stiffness increases the critical buckling load. Furthermore, it is shown that analytical results can agree well with the experimental and numerical results if the calibrated values of circumferential contact stiffness are used in the calculations. Moreover, it is shown that the contact between the steel tubes and a sandwiched concrete core of tested large-scale CFDST columns used in the comparison is relatively weak. Finally, the proposed analytical results can be used as a benchmark solution.

비대칭으로 보강된 복합재 원형 스파의 파손하중 예측 (The Prediction of Failure Load for an Unsymmetrically Stiffened Circular Composite Spar)

  • 김성준;이동건;박상욱
    • 한국항공우주학회지
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    • 제48권7호
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    • pp.505-511
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    • 2020
  • 원형 복합재 튜브를 고고도 장기체공 무인기의 주요 스파에 사용하였다. 본 논문에서는 수정된 Brazier 방법을 이용하여 비대칭으로 보강된 원형 스파의 파단하중을 예측할 수 있는 이론적인 모델을 제안하였다. 이 모델을 이용하여 비대칭으로 보강된 원형스파의 최대 허용 굽힘 모멘트를 예측하였다. 해석 결과로부터 원형 스파의 상단에 위치한 보강된 캡은 최대 허용 굽힘 모멘트를 증가시키는 것을 알 수 있다. 4점 굽힘 실험을 수행하여 스파 캡이 파손하중에 미치는 영향을 평가하였고 제안된 모델과 비교하였다. 그리고 수치해석을 수행하여 보강된 원형 스파의 거동을 분석하였다. 제안된 이론적인 모델은 실험 및 수치해석 결과와 잘 일치함을 보였다.

원형관내 나노유체의 강제대류에 관한 수치적 연구 (NUMERICAL STUDY OF NANOFLUIDS FORCED CONVECTION IN CIRCULAR TUBES)

  • 최훈기;유근종
    • 한국전산유체공학회지
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    • 제19권3호
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    • pp.37-43
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    • 2014
  • In this paper, hydraulic & thermal developing and fully developed laminar forced convection flow of a water-$Al_2O_3$ nanofluid in a circular horizontal tube with uniform heat flux at the wall, are investigated numerically. A single phase model employed with temperature independent properties. The thermal entrance length is presented in this paper. The variations of the convective heat transfer coefficient and shear stress are shown in the entrance region and fully developed region along different nanoparticles concentration and Reynolds numbers. Convective heat transfer coefficient for nanofluids is larger than that of the base fluid. It is shown that heat transfer is enhanced and shear stress is increased as the particle volume concentration increases. The heat transfer improves, as Reynolds number increases.