• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.199-207
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• 2004

Water supply facilities are recently getting larger according as domestic waterworks become multi regional water supply system. Large water supply facilities generally consist of the intake pumping station, water treatment station and water supply & distribution facilities. Although pumping stations and pipeline systems are used to pump up water, it often happens pipeline damage and flooding accident by the water hammer. As a result of this study, a pumping station is guaranteed by the computer simulation and field test analysis. Therefore these are contributed safety operation in pumping station through adjustment of the pumping station safety plan, air valve and valve closing time.

• 설비공학논문집
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• 제23권6호
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• pp.441-448
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• 2011

The energy consumption of a condensing gas boiler may be greatly reduced by the effective operation of the unit. In this study, the supply water algorithm for a condensing gas boiler control was developed by using the fuzzy logic. This includes the supply water set temperature algorithm, and the control algorithms of a gas valve, a blower and a pump. For the set temperature algorithm, the outside air temperature and the return water temperature were used as input variables. The supply water temperature difference and its slope were used as input variables of the gas valve and blower control algorithm. And the supply water temperature and the return water temperature were used as input variables of the pump control algorithm. In order to analyse performances of these algorithms, the dynamic model of a condensing gas boiler was used. The initial start-up test, the supply water set temperature change test, the outside air temperature change test, and the return water temperature change test were performed. Simulation results showed that algorithms developed in this study may be practically applied for the effective control of a condensing gas boiler.

• 한국유체기계학회 논문집
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• 제9권3호
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• pp.36-43
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• 2006

Recently, micro hydropower and it's useful utilization are taking a growing interest as a countermeasure of global worming by carbon dioxide and exhaustion of fossil fuel. The purpose of this study is to investigate the possibility of extracting micro hydropower wasted by a valve in water supply system using micro cross-flow hydraulic turbine. In order to fulfill the functions of controlling flow rate and pressure in substitute for the valve, air and water are supplied into an air suction hole which is installed on the side wall of micro cross-flow hydraulic turbine. The results show that in case of supplying a lot of air into the air suction hole, about 50% of flow rate and relatively high value of loss coefficient are controlled by the turbine. Moreover, including high possibility of applying the micro cross-flow turbine to water supply system, extended application of the turbine to the water discharge system of drainage and irrigation canal.

• 상하수도학회지
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• 제36권5호
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• pp.261-273
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• 2022

In this study, we collect water control valves that have had accidents due to existing cracks, etc. are collected, and propose investigation items for strengthening the valve structural safety evaluation through a series of analyzes from valve specifications to physicochemical properties are proposed. The results of this study are as follows. First, there was a large variation in the thickness of the body or flange of the valves to be investigated, which is considered to be very important factor, because it may affect the safety of the valve body against internal pressure and the flange connected with the bolt nut. Second, 60% of the valves under investigation had many voids in the valve body and flange, etc. and the decrease in thickness due to corrosion was relatively large on the inner surface in contact with water rather than the outer surface. It is judged that the investigation of depth included voids is very important factor. Third, all valves to be investigated are made of gray cast iron foam, and therefore it is judged that there is no major problem in chemical composition. It is judged that the chemical composition should be investigated. Fourth, as a physical investigation item, the analysis of metal morphology structure seems to be a very important factor for nodular cast iron from rather than a gray cast iron foam water valve with a flake structure. As it was found to be 46.7~68.8% of the standard recommended by KS, it could have a direct effect on damage such as cracks, and therefore it is judged that the evaluation of tensile strength is very important in evaluating the safety of the valve.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.288-293
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• 2001

This paper presents the water-hammer effect due to the rapid opening and closing of isolation valve and thruster valve in the spacecraft propulsion system. The single propellant feed system was modeled to investigate the maximum peak pressure due to the water-hammer effect. The test parameters are tank supply pressure, shape and throat length of orifice and line length. Kerosene was used as the inert simulant propellant liquid instead of hydrazine. As downstream line length after isolation valve increased from 1.5 to 2.5m, the maximum line-filling water-hammer peak pressure decreased, but the average time interval between peak pressures increased. The maximum line-filling water-hammer peak pressure with orifice was lower than without orifice, and the maximum line-filling water-hammer peak pressure with orifice at the back of isolation valve was lower than with orifice in front of isolation valve. Without orifice, the maximum water-hammer peak pressure due to the rapid opening and closing of the thruster valve was about 126% of tank supply pressure. With orifice, it decreased. As orifice throat length increased, it decreased. The maximum water-hammer peak pressure due to the rapid closing of the thruster valve with converging-diverging orifice was lower than normal orifice. It was found that the orifice as a means of pressure drop was very effective to reduce the water hammer peak pressure at the thruster valve. The results of this study can be used for the design of spacecraft liquid propulsion feed system.

• 한국유체기계학회 논문집
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• 제12권5호
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• pp.19-24
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• 2009

This paper is performed to find out the stability of water-hammer in pipe line and pump station that is happened when additional water needs demanded. At first, the water supply construction project is planned to supply $6,000\;m^3/day$ through 17.9 km pipe line. But additional demand ($1,200\;m^3/day$) happened from Cheong-ra water reservoir. In this situation, air-chamber($4\;m^3$) and vacuum breaker valve(${\varphi}100\;mm$) are needed to prevent water-hammer. When the additional water is supplied, the existing facilities (air-chamber, vacuum breaker valve) are sufficient to alleviate shock not changing capacity alteration, judging from the airspace change and rise. Therefore, there is no problem for water-hammer by installing air-chamber($4\;m^3$) and vacuum breaker valve(${\varphi}100\;mm$) at the top of Yeo-ju hill.

• 한국산학기술학회논문지
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• 제13권7호
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• pp.2853-2857
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• 2012

본 논문은 급수 설비시스템의 적정수압을 유지하는 장치로 사용되는 감압밸브(Pressure Reducing Valve)의 구조와 특성을 알아보기 위해 3차원 자동 설계프로그램인 Solidworks를 활용하여 설계하였으며 현장에서 감압밸브의 제작을 위해 2차원 도면을 작성하였다. 또한 감압밸브내의 물의 흐름을 해석하기 위하여 3차원 유한요소해석 코드인 ANSYS를 사용하여 유동해석을 실시하였다.

• 대한설비공학회지:설비저널
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• 제17권4호
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• pp.395-407
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• 1988

Transient flow in a cold-water supply system for cooling the inside of a coal mining pit was numerically simulated. Properly designed and presetted pressure reducing valves control the level of pressures of the piping system at normal or emergent conditions Quasi-steady relations to simulate the valve motion are obtained and the transient performance of the valve is investigated in the present paper. The present method reasonably simulate transient phenomena in the system including the pressure reducing valve. Excessive valve motion and column separation are simulated when the flow is abruptly reduced. A calculated example of the real system is also presented. The simulation can be used for the safety-check and the guidance for design and operation in emergent cases of the system.

• 한국산업융합학회 논문집
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• 제26권2_2호
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• pp.307-313
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• 2023

This study conducts the flow analysis on the basis of the impeller RPM of water metering valve. The software used for the flow analysis is STAR-CCM+. In terms of the structure of the metering valve, it has an impeller installed inside, and a metering chamber has inlet and outlet holes. The flow analysis on the water metering valve drew the following conclusions: Regarding the flow field in the valve, the impeller had the highest velocity distribution, and complex flow field was generated in the metering chamber. In particular, since the path between the inlet and outlet holes in the metering chamber and the valve body was narrow, there was a section that had flow field interference. The flow rate and flow coefficient distribution according to the impeller RPM were on the linear increase. Given that, it showed the feature of the valve used for water metering on the basis of the impeller RPM.

• Journal of Advanced Marine Engineering and Technology
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• 제30권3호
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• pp.396-402
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• 2006

In this study, dynamic characteristics of water hammer pressure in water supply piping system with water hammer arrester has been investigated experimentally to characterize the transient pressure of water hammer in high rise building. Experiments were conducted to verify the absorption effects by water hammer arresters with 3 different gas volumes of water hammer pressure generated by sudden valve closure. As the results, it has been found that zoning and sizing of pipe diameter for suitable flow velocity and water hammer arresters with effective pressure absorption capacity have to be installed to protect water hammer problems in building water supply piping system.