• 한국가스학회지
• /
• 제23권4호
• /
• pp.65-73
• /
• 2019

스파이럴 강관은 기존 UOE 강관에 비해 경제적이며 연속적으로 강관 제작이 가능해 수송관뿐만 아니라 구조부재로 사용이 점차 확장되고 있다. 최근 제작기술의 발달로 스파이럴 강관의 고강도 및 대형화가 가능하게 됨에 따라 대규모 장거리 수송용 파이프라인에도 적용이 시도되고 있고, 이로 인해 스파이럴 강관의 구조적 건전성과 경제성 확보를 위한 변형률 기반 설계가 요구된다. 그러나 이를 뒷받침하기 위한 스파이럴 강관의 설계 기준 전반이 제시되지 않은 실정이고, 구조적 거동에 대한 명확한 규명이 이뤄지지 못하고 있다. 본 논문은 스파이럴 파이프의 조관 과정에서 발생되는 잔류응력이 스파이럴 파이프의 휨 거동에 미치는 영향을 분석하였다. 조관으로 인한 잔류응력 평가를 위해 조관 성형각, 두께, 강도를 달리하여 스파이럴 파이프의 유한요소해석을 수행하고, 해석결과를 파이프 휨 해석에 대한 초기 조건으로 반영하여 수치해석적으로 휨 거동 변화를 조사하였다.

• 대한기계학회논문집A
• /
• 제27권11호
• /
• pp.1824-1830
• /
• 2003

The vibrational system of this study is consisted of a rotating cantilever pipe conveying fluid and the tip mass. The equation of motion is derived by using the Lagrange equation. The influences of the rotating angular velocity and the velocity of fluid flow in a cantilever pipe have been studied on the dynamic characteristics of a rotating cantilever pipe by the numerical method. The effects of a tip mass on the dynamic response of a cantilever pipe are also studied. The tip-amplitude and maximum tip-deflection of each direction are directly proportional to the tip mass of the cantilever pipe in steady state. It identifies that the influence of the fluid velocity and the rotating angular velocity of the cantilever pipe give much variation the bending tip-displacement of steady state and the bending tip-displacement of non-steady state, respectively. The influence of the rotating angular velocity gives much the deflection of axial direction.

• 한국소음진동공학회논문집
• /
• 제18권2호
• /
• pp.177-184
• /
• 2008

The dynamic stability of elastically restrained cantilever pipe conveying fluid with crack is investigated in this paper. The pipe, which is fixed at one end, is assumed to rest on an intermediate spring support. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by the energy expressions using extended Hamilton's Principle. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The influence of a crack severity and position, mass ratio and the velocity of fluid flow on the stability of a cantilever pipe by the numerical method are studied. Also, the critical flow velocity for the flutter and divergence due to variation in the support location and the stiffness of the spring support is presented. The stability maps of the pipe system are obtained as a function of mass ratios and effect of crack.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2005년도 동계학술발표대회 논문집
• /
• pp.317-322
• /
• 2005

This study is aimed to analyze the effects of heat pipe shape on the heat transfer in solar collector with a axial grooved heat pipe. In the design of a heat pipe. two of the most important criteria to be met are the operating temperature range and the maximum heat transport capacity, When the operating temperature range is known and the working fluid has been selected, the maximum heat transport capacity depends strongly on capillary pressure and liquid flow. The heat transport capacity of the heat pipe will depend on the geometry of the heat pipe, the wick structure. the vapor channel shape. groove number. cooling temperature. condenser length and pipe diameter. So various shapes are used for mathematical models of two-phase flow in grooved heat pipe. From the results. the adequate groove shape and scale are presented by considering the heat transport and capillary limitation.

• 한국지반환경공학회 논문집
• /
• 제9권3호
• /
• pp.11-15
• /
• 2008

대구경 상수도 관로는 제작 및 경제성 요인에 의해 주로 강관을 사용해 오고 있다. 상수도시설기준(건교부, 1992)에 강관두께를 결정하는 기준을 제시하고 있다. 그러나, 이 기준에는 강관 두께를 결정하는 체계적인 기준이 없다. 그래서, 매설관로에는 적용이 부적합한 Stewart 공식을 적용하여 강관두께를 결정해 왔다. 개정된 상수도시설기준(환경부, 1997) 에 부합되도록 지반여건과 각종응력을 고려하여 강관두께를 산정하였다. 그 결과를 기존의 방법에 의해 산정된 결과와 비교 검토한 후 최적 강관두께를 결정하는 방법을 제시하였다.

• 대한기계학회논문집B
• /
• 제25권3호
• /
• pp.366-372
• /
• 2001

The ice plugging process consists of placing liquid nitrogen around a pipe and removing heat until the water in the pipe freezes and provides a solid plug or seal against fluid movement. This technique enables us to repair or inspect a pipe system without shutdown of entire system. A set of test apparatus for investigation of the liquid freezing phenomena during ice plugging is prepared. This study shows the characteristics of the liquid freezing and the heat transfer with various pipe and freezing jacket conditions. And in case there is flow of the fluid inside the pipe, the flow rate which can be able to form the ice plug is identified with the effect of the pipe diameter and freezing jacket length on the plug formation. The permissible maximum flow rate for the complete plug formation is approximately proportional to the freezing jacket length at the same pipe diameter condition.

• 한국소음진동공학회논문집
• /
• 제18권1호
• /
• pp.101-109
• /
• 2008

The stability of a rotating cantilever pipe conveying fluid with a crack and tip mass is investigated by the numerical method. That is, the effects of the rotating angular velocity, mass ratio, crack severity and tip mass on the critical flow velocity for flutter instability of system are studied. The equations of motion of rotating pipe are derived by using the Euler-Bernoulli beam theory and the extended Hamilton's principle. The crack section of pipe is represented by a local flexibility matrix connecting two undamaged pipe segments. Also, the crack is assumed to be in the first mode of fracture and always opened during the vibrations. When the tip mass and crack are constant, the critical flow velocity for flutter is proportional to the rotating angular velocity of pipe. In addition, the stability maps of the rotating pipe system as a rotating angular velocity and mass ratio ${\beta}$ are presented.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1058-1062
• /
• 2004

High-temperature cylindrical stainless steel/sodium heat pipe was manufactured and tested under long-term operation. The container material was stainless steel 316L and the working fluid was sodium. The heat pipe was 25.4 mm in diameter and 1000 mm in length with a two-layer screen mesh wick. The evaporator part was 600 mm and the condenser part was 300 mm in length. Total measurement points on heat pipe were 15 points and 12 points were located in condenser part. The heat pipe was heated for 142 days(3400 hours) at $800^{\circ}C$. In the test period, the maximum temperature difference was increased from $18^{\circ}C$ o $28^{\circ}C$ and the maximum thermal resistance was as low as $0.015^{\circ}CW$.

• 한국안전학회지
• /
• 제20권2호
• /
• pp.18-25
• /
• 2005

This study performed finite element analysis on the pipe bend with various bend angles under loading conditions of internal pressure and combined pressure and bending, to investigate the effect of bend angle on the collapse behavior of pipe bend and on the stress state in the bend region. In the analysis, the pipe bends with bend angle of $5\~90^{\circ}$ were considered, and the bending moment was applied as in-plane closing and opening modes. From the results of analysis, it was found that the collapse moment of pipe bend increases with decreasing bend angle. As the bend angle decreases, also, the equivalent stress at intrados region increases regardless of bending mode. Under closing mode bending especially, the increase in stress at intrados is significant so that the maximum stress region moves from crown to intrados with decreasing bend angle.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.7-10
• /
• 2007

In case of large steel water pipe, it have been observed that its fracture mostly occurs due to the complicated outside fatigue load on the pipe in the underground. It is also well known that its damage and leakage happen mainly in a weld zone. In this study we evaluated the fatigue characteristics based on size effect and residual stress by comparing the test results on the standard specimen collected from real pipe with those on full scale pipe.