• The KSFM Journal of Fluid Machinery
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• v.4 no.4 s.13
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• pp.16-21
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• 2001

The field tests on the waterhammer were carried out for PalDang intake pumping station of the metropolitan water supply 5th stage project. The pumping station was equipped with the pump control valve as the main surge suppression device and the surge relief valve as auxiliary. However, the pump control valve had not been early controlled in the planned closing mode, and the slamming occurred to the valve which abruptly closed during the large reverse flow. Because the pressure wave caused by the pump failure was superposed on the slam surge, the upsurge increased so extremely that the shaft of the valve was damaged. It was desirable that the surge relief valve was installed in the pumping station or near the pump exit for the delay of response. After reforming the oil dashpot of the pump control valve, the sliming disappeared and the measured pressure was in fairly good agreement with the results of simulation. In case of three pumps for ${\phi}2,600$ pipeline being simultaneously tripped, the pressure head in the pumping station increased to 95.6 m, and the upsurge caused by the emergency stop of four pumps for ${\phi}2,800$ pipeline was 89.6m. We concluded that the pumping station acquired the safety and reliability for the pressure surge.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.115-122
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• 2018

Direct spring loaded pressure relief valve(DSLPRV) is a safety valve to relax surge pressure of the pipeline system. DSLPRV is one of widely used safety valves for its simplicity and efficiency. However, instability of the DSLPRV can caused by various reasons such as insufficient valve volume, natural vibration of the spring, etc. In order to improve reliability of DSLPRV, proper selection of design factors of DSLPRV is important. In this study, methodology for selecting design factors for DSLPRV was proposed. Dynamics of the DSLPRV disk was integrated into conventional 1D surge pressure analysis. Multi-objective genetic algorithm was also used to search optimum design factors for DSLPRV.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.70-77
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• 2011

A ventilation-relief valve performs as a safety-valve assembly for the liquid-propellant feeding system of space launch vehicle. This valve plays a role of relieving the vaporized propellants from propellant tanks during the filling and storing stages of propellants. Also it regulates to maintain the pressure of ullage volume of on-board propellant tanks within the safety-margin during the flight. The simulation model of ventilation-relief valve is designed with AMESim to predict and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of the opening and closing pressures and their operating durations of valve by AMESim analysis are compared with the results of mathematical methods. In addition, the results of internal flow simulation with FLUENT are utilized to improve the accuracy of valve-modeling. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditionss, which shall be used in Korea Space Launch Vehicle-II.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.813-816
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• 2011

The actuation and leakage tests of solenoid valve for propellant tank pressurization system have been conducted. The response time of solenoid valve manufactured is satisfactory to perform requirement. However, leakage was found at the upper part seat of relief valve inside solenoid valve. Solenoid valve was disassembled in order to discover leakage causes. We found out that the upper seat of relief valve was damaged. Through this study, the development possibility of propellant tank pressurization solenoid valve was confirmed.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.115-123
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• 2003

In this paper, in order to guarantee successful operation of KSR-III TVC actuator in the presence of excessive external disturbances, a relief valve is designed as a key component of the actuator. It is shown that the relief valve can resolve the stability problems which occur due to actuator failure in the presence of excessive disturbance torques on the actuator. Six degree-of-freedom simulation shows that relief valves with low operating pressure and low LOHM parameter may be better is stability and performance of the TVC actuator system.

• The KSFM Journal of Fluid Machinery
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• v.8 no.3 s.30
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• pp.16-25
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• 2005

The purpose of this study is localization of safety relief valves for Nuclear Service. The safety relief valve is the important equipment used to protect the pressure vessel, the steam generator and the other pressure facility from overpressure by discharging the operating medium when the pressure of system is reaching the design pressure of the system. We developed design technology used FEM ' CFM about safety relief valve for Nuclear Service according to ASME (or KEPIC) Code and KHNP's Technical Specification. To prove validity of a design technology, actually, we manufactured and inspected and tested the sample products designed according to a developed technology. The capacity qualification test was achieved according to requirement of ASME(or KEPIC) Code by NBBI and the functional qualification test was achieved according to ASME QME-1 for operating condition in technical specification of KHNP by NLI. Therefore we have to achieve the development of safety relief valves for Nuclear Service with our own technologies.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.741-747
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• 2010

Vent-relief valve performed as a safety-valve combination for liquid propellant feeding system of space launch vehicle, which can vent the vaporized oxygen vapor during both filling cryogenic oxidizer into tank and flight. We have designed vent-relief model by using the AMESim code to predict dynamic characteristics and simulate pneumatic behavior of valve. To validate valve model we have compared by opening time in vent model, and opening/closing pressure by mathematical methods and improved the accuracy through numerical flow analysis by using FLUENT code. In this study, we had verified design parameters and analyzed operating performances. We can use these analysis results to precedent development study on propellant feeding system of Korea Space Launch Vehicle.

• Journal of Drive and Control
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• v.12 no.4
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• pp.54-59
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• 2015

Due to the tendency to use high speed pneumatic cylinders to improve productivity, cushioning devices are adopted to decelerate the piston motion of pneumatic cylinders to reduce noise, vibration, and impact. This paper presents a comparison of the cushion characteristics of a high speed pneumatic cylinder with a relief valve type cushioning device. The system parameters selected are the damping coefficient, Coulomb friction, heat transfer coefficient, and cracking pressure of the relief valve in the air cushioning device. The integral of the time multiplied square error (ITSE) is used to quantitative measure the cushioning performance to assess the effect of varying these. The cushioning performance achieved good results when the ITSE is a minimum value. In a comparison of the piston displacement and velocity with the variations in system parameters, the heat transfer coefficients are not as significantly affected as the other. Also, the cracking pressure of the relief valve is mainly affected by the pressure and temperature in the cushion chamber.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.5
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• pp.696-704
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• 2009

In this paper, the flow characteristics through an industrial safety relief valve used to protect the crankcase room in a large-sized marine engine have been numerically investigated using the moving-mesh strategy. With the room pressure higher than the cracking one, the spring-loaded disc becomes open and then the air in the room blows off into the atmosphere, resulting in the reduction of the room pressure and then the shutoff of the disc. Numerical simulations are performed on the compressible air flow through the relief valve (${\phi}160mm$) with the initial room pressure (0.11 bar or 0.12bar) higher than the cracking one (0.1 bar). The numerical method has been validated by comparing the results with the empirical ones. Results show that the disc motion and flow characteristics can be successfully simulated using the moving-mesh strategy and depend strongly on the spring stiffness and the flow passage shape. With increasing spring stiffness, the maximum disc displacement decreases and thus the total disc-opening time also decreases. In addition, the flow passage shape makes a significant effect on the velocity and direction of the flow.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.77-84
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• 2013

The proportional pressure control valve that was used to relief valve has different dynamic characteristics on each case. Because this valve has different assembling or processing error and environmental condition. However, a customer who used the relief valve wants to have a steadily performance even if the dynamic characteristics of valve was changed. For this reason, the manufacturer try to make the robust controller that has simple structure. This paper concerns about the design of robust controller that didn't affected by plant parameter's changing. The control strategy is a model reference control that conducted by on line identification problem, gradient method and Lyapunov equation. This adaptvie control law's validity that this paper deal with was confirmed by an results of step response test or hysteresis test.