• Title/Summary/Keyword: 온도 점프

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Numerical Investigation of Flows around Space Launch Vehicles at Mid-High Altitudes (중/고고도 영역에서의 우주발사체 주위 유동에 대한 수치적 연구)

  • Choi, Young Jae;Choi, Jae Hoon;Kwon, Oh Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.1
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    • pp.9-16
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    • 2019
  • In the present study, to investigate flows around space launch vehicles at mid-high altitudes efficiently, a three-dimensional unstructured mesh Navier-Stokes solver employing a Maxwell slip boundary condition was developed. Validation of the present flow solver was made for a blunted cone-tip configuration by comparing the results with those of the DSMC simulation and experiment. It was found that the present flow solver works well by capturing the velocity slip and the temperature jump on the solid surface more efficiently than the DSMC simulation. Flow simulations of space launch vehicles were conducted by using the flow solver. Mach number of 6 at the mid-high altitude around 86km was considered, and the flow phenomena at the mid-high altitude was discussed.

Numerical Analysis of the Slip Velocity and Temperature-Jump in Microchannel Using Langmuir Slip Boundary Condition (미소채널내의 Langmuir 미끄럼 경계조건을 통한 미끄럼 속도 및 급격한 온도변화에 관한 수치해석)

  • Kim, Sang-Woo;Kim, Hyun-Goo;Lee, Do-Hyung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.3
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    • pp.164-169
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    • 2009
  • The slip velocity and the temperature jumps for low-speed flow in microchannels are investigated using Langmuir slip boundary condition. This slip boundary condition is suggested to simulate micro flow. The current study analyzes Langmuir slip boundary condition theoretically and it analyzed numerically micro-Couette flow, micro-Poiseuille flow and grooved microchannel flow. First, to prove validity for Langmuir slip condition, an analytical solution for micro-Couette flow is derived from Navier-Stokes equations with Langmuir slip conditions and is compared with DSMC and an analytical solution with Maxwell slip boundary condition. Second, the numerical analysis is performed for micro-Poiseuille flow and grooved microchannel flow. The slip velocity and temperature distribution are compared with results of DSMC or Maxwell slip condition and those are shown in good agreement.

NUMERICAL STUDY OF WEDGE FLOW IN RAREFIED GAS FLOW REGIME USING A SLIP BOUNDARY CONDITION (희박기체 영역에서 미끄럼 경계조건을 적용한 쐐기 형상 주위의 유동 해석)

  • Choi, Y.J.;Kwon, O.J.
    • Journal of computational fluids engineering
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    • v.19 no.2
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    • pp.40-48
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    • 2014
  • For rarefied gas flow regimes, physical phenomena such as velocity slip and temperature jump occur on the solid body surface. To predict these phenomena accurately, either the Navier-Stokes solver with a slip boundary condition or the direct simulation Monte Carlo method should be used. In the present study, flow simulations of a wedge were conducted in Mach-10 flow of argon gas for several different flow regimes using a two-dimensional Navier-Stokes solver with the Maxwell slip boundary condition. The results of the simulations were compared with those of the direct simulation Monte Carlo method to assess the present method. It was found that the values of the velocity slip and the temperature jump predicted increase as the Knudsen number increases. Also, the results are comparatively reasonable up to the Knudsen number of 0.05.

Study on Optimization of Temperature Jump-Bending Process for Reducing Thickness Attenuation of Large-Diameter Steel Pipe (대구경 곡관 두께감소율 제어를 위한 온도점프 벤딩 공정의 최적화에 관한 연구)

  • Xu, Zhe-Zhu;Kim, Lae-Sung;Jeon, Jeong-Hwan;Liang, Long-Jun;Choi, Hyo-Gyu;Lyu, Sung-Ki
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.4
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    • pp.21-27
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    • 2015
  • Induction bending is a method that allows the bending of any material that conducts electricity. This technology applies a bending force to a material that has been locally heated by an eddy current induced by a fluctuating electromagnetic field. Induction bending uses an inductor to locally heat steel through induction. This results in a narrow heat band in the shape to be bent. In general, the reduction of thickness attenuation of a large-diameter steel pipe is not allowed to exceed 12.5%. In this paper, in order to meet the standard of thickness attenuation reduction, a non-uniform heating temperature jump-bending process was investigated. As a result, the developed bending technique meets the requirements of thickness attenuation reduction for large-diameter steel pipes.