• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1995년도 춘계학술발표회 프로그램 및 초록
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• pp.57-57
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• 1995

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1995년도 추계 학술발표회
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• pp.63-63
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• 1995

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2002년도 춘계 공동학술발표회
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• pp.406-408
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• 2002

• 터널과지하공간
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• 제12권4호
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• pp.277-283
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• 2002

본 연구는 안쪽축이 회전하고 바깥쪽 실린더는 정지해있는 반경비가0.52이고 30$^{\circ}$ 경사진 동심 환형관내의 헬리컬 유동 특성에 관한 것이다. 비뉴튼 유체인 UC 수용액과 벤토나이트 수용액을 사용하여 안쪽축이 0~400pm으로 회전할 때 축방향 유동을 완전히 발달시킨 후 축방향 압력손실값을 측정하였다. 또한, 헬리컬 유동의 가시화는 불안정한 파를 관찰하기 위해 수행되었다. 현재 연구 결과는 표면마찰계수에 대해 로스비순(Ro)와 레이놀즈수(Re)의 관계를 나타내었다. 또한, 그 결과들은 유동 불안정성 메카니즘의 존재를 보인다. 축회전수가 증가함에 따라 압력손실이 증가하지만, 그 증가폭은 천이 및 난류영역에서는 레이놀즈수가 증가할수록 감소하며, 회전의 영향으로 유동교란이 증진되어 천이가 촉진된다. 또, 이런 유동교란의 증진은 표면마찰계수값의 증가와 함께 임계 레이놀즈수(Re$_{c}$)를 작게 만든다.

• 에너지공학
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• 제18권2호
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• pp.87-92
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• 2009

본 논문은 안쪽축이 회전하는 동심환형관 물과 비뉴튼유체의 고-액 2상 유동연구를 수행하였다. 점탄성유체의 유변학은 굴착구멍의 청결, 입자의 밖으로 수송하는 등 여러 가지 응용에 중요하다. 연구에서 투명한 아크릴관은 고체입자의 이동을 관찰하기 위하여 사용하였다. 환형관 속도는 0.3m/s에서 2.0m/s로 변한다. 머드시스템은 물과 CMC 수용액을 혼합하여 사용하였다. 연구에서 고려된 주요 변수들은 축회전속도, 유체 유동영역과 입자 주입율이다. 입자이송속도와 압력강하는 유체유량(Q, LPM)이 5~30의 범위에서 측정하였다. 물과 0.2% CMC 수용액에서 고체입자의 농도가 높을수록 압력손실이 커짐을 알 수 있었다.

• 설비공학논문집
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• 제4권4호
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• pp.342-350
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• 1992

An experimental investigation of the stenosis effects on the pressure drop and flow change in the internal flow is presented. Stainless steel tubes of small diameter(3.175mm, 3.4mm) are used for the test section of the flow loop. Percent contraction ranges from 35% to 83% and the stenosis length ratio (L/d) is varied from 2.8 to 8. Water and aqueous glycerol solutions are used for Newtonian fluids and polymer solutions of Separan AP-273 (500 wppm, 1000 wppm) for non-Newtonian fluids. Pressure loss coefficients of non-Newtonian fluids decrease just as those of Newtonian fluids. The loss coefficients of Newtonian and non-Newtonian fluids increase as the percent contraction increases and the loss coefficients of non-Newtonian fluids are larger than those of Newtonian fluids for the same stenosed tube. The loss coefficient increases as the stenosis length ratio increases.

• 오토저널
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• 제15권1호
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• pp.45-54
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• 1993

The reattachment lengths of the Non-Newtonian fluid are investigated in the sudden expansion pipes whose ratios are 2.316 and 3.368, and the range of the Reynolds numbers is 100-30000. The reattachment lengths for the viscoelastic fluid in the laminar flow region are found to be much shorter than those of the Newtonian fluid, and decrease significantly with the increase of the concentration of viscoelastic fluid is two or three times longer than those of water, and gradually increases with the increase of the concentration of viscoelastic fluid.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.465-470
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• 2006

An experimental investigation is carried out to study 2-phase vertically upward hydraulic transport of solid particles by water and non-Newtonian fluids in a slim hole concentric annulus with rotation of the inner cylinder. Rheology of particulate suspensions in viscoelastic fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, etc. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Annular fluid velocities varied from 0.2 m/s to 3.0 m/s. Pressure drops and average flow rate and particle rising velocity are measured. For both water and 0.2% CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1634-1639
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• 2004

The present study concerns a experimental study of fully developed laminar flow of a Newtonian and non-Newtonian fluid through a concentric annulus with a combined bulk axial flow and inner cylinder rotation for the various radius ratio. This study shows the fundamental difference between Newtonian and non-Newtonian fluid flow in an annulus for various radius ratio.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.324-329
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• 2001

This experimental study concerns the characteristics of a transitional flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure losses and skin-friction coefficients have been measured for the fully developed flow of $0.1\sim0.4%$ aqueous solution of sodium carbomethyl cellulose (CMC), respectively at inner cylinder rotational speed of $0\sim600rpm$. The transitional flow has been examined by the measurement of pressure losses to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients. The present results show that the skin-friction coefficients have the significant relation with the Rossby numbers, only for laminar regime. The occurrence of transition has been checked by the gradient changes of pressure losses and skin-friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficients due to the rotation in uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, is gradually declined for turbulent flow regime. Consequently, the critical(axial-flow) Reynolds number decrease as the rotational speed increases. Thus, the rotation of inner cylinder promotes the early occurrence of transition due to the onset of taylor vortices.