• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.175-178
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• 2007

Valves has been used widely in various industries. There are many purposes for valve usage in a piping system. One of them is to control the flow rate. For a design of ball valves, it is important to know the characteristics of flows inside a ball valve. In this study, the computation fluid dynamics were conducted to observe flow velocity, flow coefficient and pressure distribution using CFX 10 according to the valve angles and uniform incoming velocity.

• 한국기계기술학회지
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• 제13권1호
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• pp.81-88
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• 2011

The triple eccentric butterfly valve has metal sheet and this study about butterfly valve ceiling is an innovative approach. But it is affected by the static pressure as well as cross-current. The damage at the valve on the pipe resulted from the reflux is due to valve leakage. This study is investigated on the triple eccentric disk and it is applied with angle and the static pressure in all cases to develop cross-current triple eccentric butterfly valves. The disc with the diameter of 300A is valve against flow velocity. The entrance pressure by flow characteristics is performed with numerical analysis. As the result, valve torque production is reduced more than the conventional triple eccentric valve and entrance pressure is decreased on the increase of valve open angle. And flow coefficient can be known to be increased.

• 대한기계학회논문집B
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• 제21권6호
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• pp.725-734
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• 1997

The effect of helical intake port geometry on in-cylinder swirl flow characteristics was studied. Two helical intake ports were selected to change swirl ratio, mean flow coefficient with the variation of valve lifts, valve eccentricity ratios and axial distance. The measurements were made by using an impulse swirl meter. The port B modified to increase the swirl ratio( $R_{s}$) had the tendency of the increased non-dimensional rig swirl ( $N_{r}$) distribution in comparison with that of the port A. And the $N_{r}$ distribution was remarkably improved at low valve lifts. The modification of the geometry to increase the swirl ratio ( $R_{s}$) in helical intake port resulted in the decrease of the mean flow coefficient ( $C_{f(mean)}$) regardless of valve eccentricity ratio ( $N_{y}$). And also non-dimensional rig swirl ( $N_{r}$) in the high valve lift affected the calculation of swirl ratio considerably.onsiderably.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.59-72
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• 1998

This experimental study was carried out to investigate the characteristics of the in-cylinder eccentricity swirl flow generated by a 4 valve cylinder head with a tangential and a helical intake port. the measurements of the in-cylinder velocity field have been made by a two-channel LDA system. The mean flow coefficient(Cf(meam)), swirl ratio(Rs) and mass flowrate with valve eccentricity ratios and an intake port partition between the two intake ports were measured in the steady flow test fig using the ISM(impulse swirl meter). The experimental results indicated that the mass flowrate through the tangential intake port was 19% and 7.7% more than that of the helical intake port in case of with and without intake port partition respectively. There was a tendency to be a single rotation flow in swirl flow fields formed by a 4 valve cylinder head because of the interaction between the two intake ports. As the intake port partition was not set between flow coefficient(Cf(mean)) was 7.35%.

• 대한기계학회논문집A
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• 제35권5호
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• pp.487-494
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• 2011

LNG / LNG-FPSO선박에 사용되는 안전밸브는 배관 시스템으로부터 유체를 방출하여 시스템의 압력을 일정하게 유지시키는데 중요한 역할을 한다. 이러한 안전밸브의 기능적 특성으로 인해 유출계수는 밸브의 성능 중 가장 큰 비중을 차지하며, 선급의 인정을 받기 위해서는 0.8이상의 유출계수가 요구되고 있다. 밸브 성능을 향상시키기 위해서 밸브 내부에서 발생하는 유동특성에 대한 정확한 이해가 필요함에도 불구하고 대부분의 밸브 설계의 경우 현장 작업자들의 경험과 실험에 의한 시행착오에 의존하고 있다. 본 논문에서는 안전밸브에 대한 유동해석을 통해 밸브 내부에 발생하는 압축성 유동현상을 고찰하였고, 실험과 해석에 의한 유출계수를 비교하여 유동해석의 타당성을 검증하였으며, 안전밸브를 지나는 공기의 질량유량을 예측하기 위한 유동해석 모델을 확립하였다.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.82-88
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• 1999

The object of this study is to find new evaluation index for in-cylinder flow chracteristics istead of current swirl, tumble coefficient using steady flow test rig on intake port system. To this end, port flow system. To this end, port flow rig test was conducted on DOHC head varying intake valve lift respectively. Finally combination angular coefficient and inclination angle were introduced as new evaluation index for in-cylinder angularflow characteristics instead of swirl and tumble coefficient.

• 한국산업융합학회 논문집
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• 제25권4_2호
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• pp.541-547
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• 2022

Before making a prototype, we predicted the inlet/outlet differential pressure and flow coefficient, which are the most basic design data for the valve through the design and numerical analysis of the trim, which is the most important in the localization development of the 1500Ib high differential pressure control valve used for boiler feed water. As a result, the design value and the analysis value were found to be about 98% similar. The flow field within the fluid velocity of 23m/s to prevent cavitation was also found. The result of the numerical analysis on thermal stress due to the characteristics of valves exposed to high temperatures showed that it was found to be about 18% less than the allowable stress of the bolt fixing the trim. When all loads such as pressure, self-weight, and vibration are applied, however, it is judged to go beyond the currently calculated thermal stress, exceeding the allowable stress.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.177-180
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• 2007

A three dimensional numerical analysis has been made for the cone disk control valve and the flat disk control valve. The simulation of the incompressible flow in the each control vale are performed by using the commercial code. Six flow cases of each control valve are investigated.

• 한국유체기계학회 논문집
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• 제14권6호
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• pp.11-17
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• 2011

The cause of waterhammer phenomenon due to valve closing which is installed on pipeline is clarified in this study. Also if waterhammer phenomenon occurs on simple pipeline, expensive facilities like pressure relief valve is adapted to protect pipeline from waterhammer so far. But this study shows that waterhammer phenomenon can be suppressed by just simple modification of valve control sequence, and this technique is verified by simulation and site experiment.

• 한국자동차공학회논문집
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• 제2권1호
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• pp.26-37
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• 1994

In this study, flow of a model intake port/valve system is analyzed by using low Reynolds number $k-{\varepsilon}$ model. Discharge coefficient was obtained from computational results for the various cases of valve lifts. Discharge coefficient becomes maximum when the valve lift is 20mm, and does not increase or decrease in proportional to valve lift. Most of pressure drop and production of turbulent kinetic energy occur at the edge points of the valve and the valve seat Thus, in order to improve discharge coefficient, rounding of edge points in valve and valve seat is recommended. As valve lift is increased, the velocity of the intake jet in the valve passage decreases, and the direction of the jet is more inclined toward the valve seat.