• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.6
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• pp.599-606
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• 2009

Main source of URN(underwater radiated noise) which is related to the ship's survivability is divided into two groups. Cavitation is the main source of URN when the speed of ship is upper than CIS(cavitation inception speed). But when the speed of ship is lower than CIS, the main source of URN is the structure-borne noise on the hull which is originated from propulsion system, pump system and trnasmitted vibration of the pipe system. In this paper, to reduce the vibration of discharge pipe and valve system, back flow prevent globe valve and new rubber mount are applied to the ship. As the result of applying new valve and mount, the vibration is reduced drastically.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.518-523
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• 2009

Main source of URN(Underwater Radiated Noise) which is related to the ship's survivability is divided into two groups. Cavitation is main source of URN when the speed of ship is upper than CIS(Cavitation Inception Speed). But when the speed of ship is lower than CIS, main source of URN is structure-borne noise on the hull which is originated from propulsion system, pump system or transmitted vibration of pipe system. In this paper, to reduce the vibration of discharge pipe and valve system, back flow prevent globe valve and new rubber mount are applied to the ship. As the result of applying new valve and mount, the vibration is reduced drastically.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.102-107
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• 1996

The blowdown transient pipe flows resulting from the actuation of the safety/relief valve (SRV) under valve opening conditions have been analyzed. The analytical model has been developed for a uniform pipe with friction through which the flow is discharged into a suppression pool in case of a sudden opening of the SRV The piping flow characteristics and dynamic loads are calculated. Effects of system pressure, pipe length and submergence depth are included.

• Nuclear Engineering and Technology
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• v.36 no.4
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• pp.285-294
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• 2004

Pressure wave propagation in the discharge piping with a sparger submerged in a water pool, following the opening of a safety relief valve, is analyzed. To predict the pressure transient behavior, a RELAP5/MOD3 code is used. The applicability of the RELAP5 code and the adequacy of the present modeling scheme are confirmed by simulating the applicable experiment on a water hammer with voiding. As a base case, the modeling scheme was used to calculate the wave propagation inside a vertical pipe with sparger holes and submerged within a water pool. In addition, the effects on wave propagation of geometric factors, such as the loss coefficient, the pipe configuration, and the subdivision of sparger pipe, are investigated. The effects of inflow conditions, such as water slug inflow and the slow opening of a safety relief valve are also examined.

• International Journal of Fluid Machinery and Systems
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• v.6 no.4
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• pp.213-221
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• 2013

The characteristics of the thrust for ship propulsion equipment directly driven by air compressed by pressure fluctuation in a blower piping system are investigated. The exhaust valve is positioned upon the air ejection hole in the discharge pipe in order to induce the large-scale pressure fluctuation, and the effects of the valve on the pressure in the pipes and the thrust for the propulsive nozzle are examined. The pressure in the pipes decreases immediately after the valve is opened, and it increases just before the valve is closed. The thrust for the propulsive nozzle monotonically increases with increasing number of revolutions and depth. The interfacial wave in the nozzle appears in the frequency of approximately 4Hz, and it is important for the increase of the thrust to synchronize the opening-closing cycle for the exhaust valve with the generation frequency of the interfacial wave. The finite difference lattice Boltzmann method is helpful to investigate the characteristics of the flow in the nozzle.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.259-264
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• 2000

The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve Uk: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient( $C_v$) and the resistance coefficient( K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and $C_v$ and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.

• The KSFM Journal of Fluid Machinery
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• v.9 no.5 s.38
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• pp.14-21
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• 2006

In general, the hollow jet valve, the fixed cone valve had been used for the urgency released or maintenance of the flow rate. Nowadays, the butterfly valve, the gate valve are applied in economic performance and operation maintenance more than the hollow jet valve, the fixed cone valve. However, in the case of butterfly valve, it should be required the strict application standard to the cavitation coefficient because the structural axis and disk were situated in pipe channel and the occurring the shock problem by Karman Vortex. Therefore, there were investigated the valve cavitation and accident investigation by field survey to establish the applicable extensibility of the urgency released valve as the preliminary study.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.105-109
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• 2008

A safety valve has a valve mechanism for the automatic release of gas from piping system when the pressure exceeds preset limit cause of a defect of a pressure regulator, condensation of water in a pipe. Therefore, for the safety of pressure regulating station, it is essential to study the flow regime and characteristics of safety valve. This article presents the numerical analysis on the flow analysis, the ejection capacity and required effective discharge area of the safety valve that is established in pressure regulating station. Then, the results are compared and analyzed with domestic and foreign regulations such as API(America Petroleum Institute), EN(European Standard), and NF(Norme Francise). Moreover, the installation number of safety valve is considered by using domestic and foreign regulations and maximum reguired effective discharge area of safety valve.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.613-616
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• 2005

In general, the hollow jet valve, the fixed cone valve had been used for the urgency released or maintenance of the flow rate. Nowadays, the butterfly valve, the gate valve are applied in economic performance and operation maintenance more than the hollow jet valve, the fixed cone valve. However, in the case of butterfly valve, it should be required the strict application standard to the cavitation coefficient because the structural axis and disk were situated in pipe channel and the occurring the shock problem by Karman Vortex. And, the judgment data for choice were slight lowdown in water supply and drainage facilities standard or Japanese penstock technology standard, various standard of KOWACO etc. Therefore. there were investigated the valve inside phenomenon (cavitation, disk chattering, vibration) by velocity of flow and the stability examination of body by high velocity of flow through flow scale model test using the numerical analysis and PIV to establish the applicable extensibility of the butterfly valve for the urgency released valve.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.196-201
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• 1997

In point of noise and vibration, it is easy to occur a noise and vibration, because the reciprocal compressor is composed of crank shaft, rod piston and etc. Therefore, it is important to understand the mechanism of reciprocal compressor. In this study, we measured the sound pressure level of compressor. There are two dominent frequencies. The first of one results from the suction part. In suction process, the suction valve flutteres, and it produces the noise of the first frequency. The other results from the structural vibration of the shell resonated by discharge pipe. Thus, to reduce the noise of compressor, it will be most efficiency to redesign muffler for the first frequency and discharge pipe for the second frequency.