• 한국자동차공학회논문집
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• 제15권1호
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• pp.186-192
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• 2007

In general, pulsation damper is installed in fuel rail for conventional MPI engine to decrease undesirable noise in vehicle cabin room. However, pulsation damper is so expensive that there are prevailing studies to reduce fuel pressure pulsations with integrated damping effect. This paper is one of basic studies for development of fuel rail to abate pulsations with self-damping effect. Primarily, the pressure pulsation characteristics was investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. A high aspect ratio or thin wall was found to absorb the pressure pulsations effectively. But volume effects on the fuel pressure pulsation reductions were not especially significant than cross section effects because volume increment rate is larger than pressure pulsation reduction rate. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure change period increases on the basis of same lengths of supply line and fuel rail as the volume is enlarged and/or the thickness of wall is thinned.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.813-816
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• 2006

Complex pressure pulsation phenomenon in fuel rails is generated by rapid opening and closing of injectors and it commonly causes undesirable noise. In this study, fluid-structure interaction analyses based on CFD and FEM have been conducted to examine the pulsation damping characteristics for different shapes of fuel rails. It is shown from the present results that the fuel rail with a high aspect ratio rectangular cross section seems to be best in order to reduce the pressure pulsations. It also agrees well with the previous experimental test by Mizuno, K. et al.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.332-336
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• 2008

A pulsation damper is usually mounted on the fuel rail to diminish undesirable noise in the vehicle cabin room. However, pulsation dampers are quite expensive. Therefore, several studies have focused on reducing fuel pressure pulsations by increasing the self-damping characteristics of the fuel rail. This paper is a basic study in the development of a fuel rail that can reduce pulsations via a self-damping effect. In this study, the pressure pulsation characteristics were of investigated with respect to the aspect ratio of the cross section, wall thickness, and fuel rail material through oil hammer simulations. An oil hammer simulation was performed in advance to simulate the pressure pulsations at the resonant speed, which is a time-saving way. The pressure pulsation peak of fuel rail was observed to rise as the injection period increases. Increase of the aspect ratio and decrease of the wall thickness can reduce the pressure pulsation efficiently.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1143-1147
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• 2004

A mechanical type pulsation dampener for the diaphragm metering pump has been developed. The pulsation pressure is an inevitable phenomenon for the positive displacement pump such as cam operated or solenoid operated metering pump. The pulsation pressure of the metering pump could be the noise source and would be harmful for the piping system which delivers hydraulic fluid. Developed pulsation dampener consists of three coil springs which have different spring constant and height each other. Depending on pressure magnitude of the piping system, total hydraulic pressure on damping diaphragm which compresses coil springs will be varied. Force equilibrium of the pulsation dampener will be set by manual by adjusting the compressed coil spring height. During the discharge stroke, pulsation dampener stores potential energy that is released as the pumping diaphragm back to an initial position during the suction stroke.

• 한국소음진동공학회논문집
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• 제15권8호
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• pp.988-995
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• 2005

Vibration has been severly increased at the branch pipe of main steam header since the commercial operation of nuclear power plant. Intense broad band disturbance flow at the discontinuous region such as elbow, valve, and header generates the acoustical pulsation which is propagated through the piping system. The pulsation becomes the source of low frequency vibration at piping system. If it coincide with natural frequency of the pipe system, excessive vibration is made. High level vibration due to the pressure pulsation related to high dynamic stress, and ultimately, to failure probability affects fatally the reliability and confidence of plant piping system. This paper discusses vibration effect for the branch pipe system due to acoustical pulsations by broad band disturbance flow at the large main steam header in 700 MW nuclear power plant. The exciting sources and response of the piping system are investigated by using on-site measurements and analytical approaches. It is identified that excessive vibration is caused by acoustical pulsations of 1.3 Hz, 4.4 Hz and 6.6 Hz transmitted from main steam balance header, which are coincided with fundamental natural frequencies of the piping structure. The energy absorbing restraints with additional stiffness and damping factor were installed to reduce excessive vibration.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.933-938
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• 2002

A pulsation of fluid in a pipe sometimes causes severe vibration of pipe. The inertia, damping and stiffness characteristics of pipe will be changed by the effect of fluid-structure interaction. The velocity and pressure of fluid will impose the force to a bended shape pipe. In this paper, a pipe with fluid flow is modeled by finite element method and the fluid force from pulsation is also modeled by the fluid dynamics. The vibration of pipe conveying pulsating fluid flow can be estimated by taking into consideration of fluid-structure interaction.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.391.1-391
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• 2002

A pulsation of fluid in a pipe sometimes cause severe vibration of pipe. The inertia, damping and stiffness characteristics of pipe will be changed by the effect of fluid-structure interaction. The velocity and pressure of fluid will impose the force to a bended shape pipe. In this paper, a pipe with fluid flow is modeled by finite element method and the fluid force from pulsation is also modeled by the fluid dynamics. The vibration of pipe conveying pulsating fluid flow can be estimated by taking into considering of fluid-structure interaction.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.592-596
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• 2012

This paper presents numerical analysis result of rotor-bearing system of a multi-stage high pressure pump. Especially resonance possibility, stability and damping factor are estimated for a selected commercial multi-stage high pressure pump. The result shows that it is not easy to avoid resonance of rotor-bearing system against main excitation forces which are residual unbalance force and pressure pulsation. This makes damping effect be more important.

• Journal of Mechanical Science and Technology
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• 제18권11호
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• pp.1909-1915
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• 2004

The hermetic rotary compressor is one of the most important components of an air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration occurs due to gas pulsation during the compression process and to unbalanced dynamic force. In order to reduce noise and vibration, it is necessary to identify their sources and transmission path and effectively control them. Many approaches have been tried in order to identify the noise transmission path of a compressor. However, identification has proven to be difficult since the characteristics of compressor noise are complicated due to the interaction of the compressor parts and gas pulsation. In this study, the statistical energy analysis has been used to trace the energy flow in the compressor and to identify the transmission paths from the noise source to the exterior sound field.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.964-968
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• 2003

Hermetic rotary compressor is one of the most Important components for air conditioning system since it has a great effect on both the performance and the noise and vibration of He system. Noise and vibration of rotary compressor is occurred due to gas pulsation during compression process and unbalanced dynamic force. In order to reduce noise and vibration. it is necessary to identify sources of noise and vibration and effectively control then. Many approaches have been tried to identify noise sources of compressor. However, compressor noise source identification has proven to be difficult since the characteristics of compressor noise are complicated due to the interaction of the compressor parts and gas pulsation. In this work, Statistical Energy Analysis has been used to trace the energy flow in the compressor and identify transmission paths from the noise source to the sound field.