• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.10a
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• pp.34-34
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• 1999

일반적으로 배관계를 통하는 유체 유량을 조절하거나 감압하는 목적으로 각종 밸브가 널리 이용되고 있다. 이러한 밸브는 작동 유체의 종류나 밸브형상에 따라 여러 가지로 분류할 수 있으나, 밸브가 유동에 미치는 저항특성, 밸브에서 발생하는 유동관련 소음진동, 기밀도, 내구 및 보수성 등을 고려하여 적절한 밸브를 선정하게 된다. 종래 버터플라이 밸브는 주로 비압축성 유체유동을 조절하기 위하여 사용되어 왔으나, 최근 다양한 방면에서 압축성 유동을 제어하기 위하여 그 활용이 증대되고 있다. 이것은 버터플라이 밸브의 형상이 매우 단순하여 밸브가 유동에 미치는 저항이 작으며, 제작 및 설치가 용이하기 때문이다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.98-103
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• 1992

전세계적인 에너지 절약과 환경보존에 대한 관심과 요구가 증가함에 따라 소비전력규제와 CFC삭감에 대응한 국제경쟁력 확보가 중요한 과제로 대두 되고 있다. 이러한 상황변화에 따라 냉동 공조기기의 심장부인 압축기에 대 해서도 고효율 및 저소음화의 요구가 한층 높아졌다. 따라서 가혹한 환경에 도 견딜 수 있는 압축기의 개발은 필수적이라 할 수 있다. 소형밀폐형 압축 기는 크게 두 부분으로 나뉘어진다. 그 하나는 모터에 의한 회전구동부이고, 다른 하나는 실린더와 피스톤 그리고 밸브로 구성된 압축기구부이다. 그 중 에서 밸브는 진동 및 소음에 영향을 미치는 기본요소가 된다. 압축기의 밸브 는 근본적으로 밸브포트와 실린더 형상에 의해 결정되며, 이런 형상조건하에 서 밸브는 연속적인 운전이 되어야 하므로, 그 응답성이 좋아야 하고 무엇보 다도 자체의 신뢰성도 확보되어야 한다. 따라서 밸브의 동적특성과 응력 분 포를 정확히 예측하는 것이 중요한 과제가 된다. 본 논문에서는 컴퓨터를 이 용한 밸브의 동적특성과 응력해석을 위해 밸브의 형상을 유한요소 패키지인 ANSYS를 이용하여 해석하고, 그 모델링 및 해석이 타당성을 검토하기 위하 여 동적 특성해석은 홀로그래피(Holography) 기술을 이용하여 실험하고, 응 력해석은 스트레인 게이지(strain gage)를 이용하여 결과를 얻어서 서로 비 교하여 보았다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.731-736
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• 2011

A pneumatic driving solenoid valve operates pneumatic control devices by opening/closing operating flow passage when the command is given by control system for the liquid-propellant feeding system of space launch vehicle. The simulation model of pneumatic driving solenoid valve is designed with AMESim to verify the designs and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of their operating durations of valve by AMESim analysis are compared with the results of experiments. In addition, the results of internal flow simulation with FLUENT are utilized to improve the accuracy of valve-modeling. Using the model, we analyze performance of valve; opening/closing pressure, operating time on various design factors; shape of control valve seat, drainage seat, rate of sealing diameter, volume of control cavity. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditions, which shall be used in Korea Space Launch Vehicle-II.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.50-55
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• 2015

This study examined the relationship between the shape of the inside of the PRV and the cavitation of the water supply system of an apartment house. In this paper, nine types of PRV with different gaps and shapes were analyzed numerically using a 3D model embedded in the commercial code, ANSYS-CFX. The lowest pressure and the maximum velocity occurred at the narrow gap, which is located at the between the stem and the disk. When the gap size was increased, the vapor volume fraction was always greater than 0, but the vapor volume fraction of the type of expansion pipe approached 0. These results indicate that the cavitation of PRV can be reduced by a shape change to the type of expansion pipe.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2049-2058
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• 1992

In this work, a 6 degree of freedom lumped mass model is constructed for an OHC-type cam valve train analysis, and the model is verified experimentally. Using the verified model, an optimum cam profile is designed to minimize the maximum contact force between cam and follower under the constraints such as cam lift and cam event angle. The designed cam was carefully machined and tested experimentally. As operating the designed cam shaft on the test rig, the valve motion was precisely measured with laser displacement meter and the contact force was indirectly monitored by measuring strain at a certain point of the finger follower. Judging from the model simulation and experiment results, the maximum contact force can be reduced as much as more than 16.7 percent under maintaining the original valve flow area by adopting the optimum cam profile.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.35-47
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• 2011

Dynamic characteristics of a flow control valve, which plays an important role in thrust and O/F control of liquid rocket engines, have been analyzed by the AMESim simulator modeling. The speed control method was proposed for the control of the flow valve equipped with a BLDC motor. The experimental results demonstrated the feasibility of systematical application as well as the performance of the speed control method. Moreover, the speed control method for BLDC motor is much simpler than the P control method in complex flow systems. With the speed control method, the control flow characteristics were evaluated according to plunger shapes. Consequently, same plunger shape proved to be more efficient in the mixture ratio control operated by two flow valves. It was also shown that the appropriate modification of plunger shapes could reduce the mixture ratio perturbation by 0.5%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.995-999
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• 2017

The factors affecting the flow coefficient of a control valve were identified and analyzed. The flow coefficient of a control valve are affected by not only Reynolds Number but also the figure and the roughness of the inlet/outlet pipes. Therefore, the flow coefficient is not a constant value. For the purpose of use in the system such as LRE, requiring the exact flow-coefficient of a control valve, the flow-coefficient should be measured under similar Reynolds Number using the inlet and outlet pipes which have the same figure and roughness with a real system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.1
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• pp.14-21
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• 2008

In this study, flow characteristics of a small-sized butterfly valve with the valve disk diameter of 25.4 mm have been investigated experimentally for the valve closed angles. In order to examine the flow characteristics of the butterfly valve, loss coefficient (Kv) was obtained at the valve closed angles of 0$^{\circ}$, 5$^{\circ}$, 10$^{\circ}$, 20$^{\circ}$ and 30$^{\circ}$. In addition, the effects of the valve disk edge shape were examined. As the result of the experiment, the maximum loss coefficient (Kvmax) was decreased with the increase of the valve closed angle, and it had the maximum decrease ratio at the valve disk angles of 0$^{\circ}$~5$^{\circ}$. The valve disk edge shape have an effect on the loss coefficient of the valve around the small valve closed angle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.913-918
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• 2016

A three-way reversing valve, which provides rapid and accurate changes in the water flow direction without requiring any precise control device, is used in automotive washing machines to remove oil and dirt that remain on the machined engine and transmission blocks. Because of the complicated shape of the bottom-plug, however, cavitation occurs in the plug. In this study, the cavitation index and POC (percent of cavitation) were used to quantitatively evaluate the cavitation effect occurring in the bottom-plug on the downstream side. An optimal shape design was conducted via parametric study with a simple CAE model to avoid time-consuming CFD analysis and hard-to-achieve convergence. To verify the results of the numerical analysis, a flow visualization test was conducted using a specimen prepared according to ISA-RP75.23. In this test, the flow characteristics, such as cavitation occurring on the downstream side, were investigated using flow test equipment that included a valve, pump, flow control system, and high-speed camera.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.24-27
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• 2010

This paper presents the design optimization of a linear actuator for fast response of electromagnetic engine valve. The optimization is performed using generic algorithm which is one of global search techniques and not highly dependent on either initial conditions or constraints in the solution domain to maximize the mechanical frequency of the armature mass and valve spring stiffness for fast response of the engine valve. In the results, the mechanical frequency is improved by 30 %.