• Journal of Power System Engineering
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• v.12 no.5
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• pp.20-26
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• 2008

양산되는 승용차용 토크 컨버터 내부의 유동을 LDV 측정 기술을 이용하여 정량화했다. 속도비 0.4와 0.8 경우에 대한 속도 측정을 통해 임펠러 유로 중간과 출구 영역의 질량 유동율 특성을 분석했다. 측정 단면의 속도 분포는 유로의 위치와 속도비에 따라 많은 차이를 보이며, 특히 속도비 0.8 조건에서 임펠러 유로 중간영역 흡입면 부근의 유동은 유동박리에 의한 재순환 현상을 나타내며, 이와는 대조적으로 출구 영역에서는 흡입면을 따라 역류 현상이 발생한다. 임펠러 유로 내부의 유동은 각 영역에서 속도비에 따라 개별적 유동 특성을 보인다. 질량 유동율은 모든 속도비와 측정단면에서 주기적인 변화를 보이며, 또한 터빈의 순간적인 위치가 임펠러 유로 측정단면의 질랑 유동율에 매우 큰 영향을 미치는 것이 밝혀졌다 따라서 토크 컨버터 임펠러의 유로 방향 유동 특성 변화는 컨버터 설계에 중요하게 고려되어야 할 것으로 보인다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1128-1146
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• 1989

본 논문에서는 2상 횡유동의 진동 메카니즘을 규명하기 위한 실험계획의 일환으로 실시된 실험으로 부터 튜브집합체의 추가질량(hydrodynamic mass)과 감쇠 (damping)에 대해 고찰하였다. 실험은 튜브배열과 피치 대 직경비(pitch-over-di- ameter:.rho./ｄ)가 상이한 튜브집합체에 대해 2상 유체를 모의한 공기-물(air-water) 혼합물에서 수행하였다. 액체상태로부터 99%의 보이드율까지 변화된 2상 유체의 유량은 튜브가 유체탄성 불안정성 (fluidelastic instability)에 도달할 때까지 점진적으로 증가하였다.

• Journal of Energy Engineering
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• v.9 no.3
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• pp.221-227
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• 2000

본 논문은 냉각된 원관내에서 유동하는 프로필렌글리콜 수용액의 제빙에 관하여 실험한 것이다. 실험은 수용액의 질량농도, 수용액의 유속, 관벽의 온도, 펌프의 압력 등을 변화시키면서 행하였다. 그 결과 관내에서의 제빙량은 프로필렌글리콜 수용액의 관내유속, 벽면과 냉각도 및 수용액의 농도에 영향을 받고 있었고, 수용액의 질량농도가 낮을수록 또 시험수용액의 유속이 빠를수록 관내에서의 제빙량은 증가하는 경향을 띄었다. 그리고 관내제빙율에 영향을 미치는 인자들의 효과를 검토하여 관내제빙율에 관한 우차원식을 얻었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.10
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• pp.817-824
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• 2015

Experiments were carried out to investigate the flow and mass transfer characteristics of an orifice nozzle. Measurements of primary and suction flow rates, dissolved oxygen concentration, and electric power were obtained. Vertically injected mixed-jet images were captured by a direct visualization technique with a high speed camera unit. The mass ratio, volumetric mass transfer coefficient, and mass transfer performance were calculated using the measured data. As the primary flow pressure increases, the mass ratio decreases slightly, while the volumetric mass transfer coefficient and electric power increase. As the primary flow pressure increases and the mass ratio decreases, the mass transfer rate increases because of the fine bubbles and wider distribution of the bubbles.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.699-704
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• 2001

The purpose of this study is to present the atomization characteristics of 2-phase internal mixing nozzle. The obtained results are considered as the essential information of understanding the spray characteristics from the nozzle exit of an aerated nozzle. In this study, SMD and AMD are mainly measured at the distance of Z=10, 20, 50, 80, 120 and 170mm from the nozzle tip. The liquid flow rate was kept at 1.8g/s and the air feeding pressure was changed from 10kpa to 100kpa increasingly. The analysis of the acquired data was performed by 2-D PDPA system and in order to get the realibility, the number of data used in calculating the SMD & AMD were 10,000 samples.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.745-751
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• 2012

Hybrid rocket shows interesting characteristics of complicated mixing layers developed by interactions between turbulent oxidizer flow and mass flow from surface due to fuel vaporization. In this study, compressible LES with a ring structure attached at the entrance of the combustor are performed. According to one recent report, adding a ring structure in the middle of the combustor helps increasing regression rate. From the numerical results, it is seen that vortex structures near the wall becomes stronger due to the interaction with surface mass injection, and the local heat flux increases due to the vortices. This phenomenon is obviously related to the generation of dimple structures which are seen in the number of experiments. Also, the ring structure at the entrance induces strong vortex flow which enhances heat transfer to the wall surface and mixing between fuel and oxidizer as well as reaction efficiency.

• Computational Structural Engineering
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• v.9 no.1
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• pp.55-64
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• 1996

Sloshing frequencies of the fluid in rectangular tanks with a bottom-mounted rectangular block are determined by linear water wave theory. Velocity potential is decomposed into those for the wall-induced waves, and the reflected, transmitted, and scattered waves by the block. The reflection and transmission coefficients are determined using the continuity conditions of mass flux and energy flux on the common vertical boundaries of the fluid regions, and the boundary conditions on the both sides of the block. The analysis results indicate that the sloshing frequencies reduce, as the block becomes tall and vade and as the block moves toward the center. The variations of the sloshing frequencies due to the block are found to be more sensitive in broad thanks than is tall tanks.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.476-482
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• 2009

The effect of pintle shape on the thrust level of pintle-nozzle Solid Rocket Motor(PNSRM) was studied numerically using the Spalart-Allmaras turbulent model of Fluent. Mass flow rate of PNSRM was always less than theoretical value and the extent of decrease in mass flow rate grew in the large pintle because of increase in the relative boundary layer thickness between pintle body and nozzle wall. The bigger pintle size was, the more thrust of pintle tip pressure was obtained. Meanwhile the more thrust of nozzle and chamber pressure decreased. Hence, total thrust of big pintle was less than a small pintle under same throat area condition. Specific impulse was relatively flat for all pintle shape.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.75-83
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• 2005

A steady transonic dilute premixed combustion in a diverging channel is investigated by using asymptotic analysis. This model explores the nonlinear interactions between the near-sonic speed of the flow, the small changes in geometry from a straight channel, and the small heat release due to the one-step first-order Arrhenius chemical reaction. The reactive flow is described by a nonhomogeneous transonic small-disturbance (TSD) equation coupled with an ordinary differential equation for the calculation of the reactant mass fraction in the combustible gas. Also the asymptotic analysis reveals the similarity parameters that govern the reacting flow problem. The results show the complicated nonlinear interaction between the convection, reaction, and geometry effects and its effect on the flow behavior.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.382-388
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• 2006

This study experimented to understand the effect of transporting ice slurry through in pipe with valve. And at this experiment it used ethylene glycol-water solution and a concentration is 30wt%. The experimental apparatus was constructed of ice slurry generation tank, turbo flow meter, manometers for differential pressure measuring, PIV system for flow pattern measuring. illumination and along a horizontal circular tube with valve as test section. The experiments were carried out under various conditions, with velocity of fluid at the entry ranging from 0.5 to 1.5 m/s and concentration of IPF is 30%. Also valve open rate is 50%, 75%, 100%.