• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.116-121
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• 2000

During the operation, fatigue failures and cracks of duct plate due to excessive duct vibration occurred in the fan-duct systems of fossil fueled boilers. We measured static pressure variation(pressure pulsation) in the outlet, and also measured vibration at the outlet duct of a centrifugal fan. It was found that strong pressure Pulsation caused by the inlet vortex occurred in inlet vane of centrifugal fan in the middle range of vane opening. Thus, excessive duct vibration is caused by strong pressure pulsation. In this paper, it is shown that the frequency and amplitude of pressure pulsation depend mainly on vane opening and are compared with duct vibration. Also, effective solution for reducing pressure pulsation and vibration are presented.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.82-87
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• 2000

During the operation, fatigue failures and cracks of duct plate due to excessive duct vibration occurred in the fan-duct systems of fossil fueled boilers. We measured static pressure variation(pressure pulsation) in the outlet, and also measured vibration at the outlet duct of a centrifugal fan. It was found that strong pressure pulsation caused by the inlet vortex occurred in inlet vane of centrifugal fan in the middle range of vane opening. Thus, excessive duct vibration is caused by strong pressure pulsation. In this paper, it is shown that the frequency and amplitude of pressure pulsation depend mainly on vane opening and are compared with duct vibration. Also, effective solution for reducing pressure pulsation and vibration are presented.

• 드라이브 ㆍ 컨트롤
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• 제11권2호
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• pp.1-8
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• 2014

In this study, the authors carried out experiments and numerical simulations in order to clarify the pressure pulsation characteristics in multiple-delivery rotating-cam and stationary-cylinder type radial piston pumps. Also, a tee filter was applied to the pump in order to mitigate the pressure pulsation. Through the experiments and simulations, it was known that pressure pulsation with a magnitude higher than 40% of the mean load pressure could occur in the pump used in the experiments. Moreover, it was confirmed that a tee filter designed in this study could effectively mitigate the pressure pulsation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.667-669
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• 2014

Development of 3 cylinder turbo charger engine is increasing due to engine down-sizing, cost reduction and emission regulations. However, 3 cylinder engine makes higher Exhaust manifold gas pressure(P3) pulsation than 4 cylinder engine and it generate boosting air with high pulsation. The mechanical waste-gate turbocharger just controlled by the boosting air has higher movement because of this high pulsation boosting air. This causes high vibrations to wasted gate and accelerate wear of the linkage system. So we need to understand out of the exhaust gas pressure pulsation changed by turbocharger compressor pressure(P2) Pulsation. In this study, we discuss how to prevent to abnormal movement of the turbo actuator by stabilized P2 Pulsation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.699-702
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• 2002

Shunt valves implanted in the subcutaneous tissue of brain to treat patient with hydrocephalus were numerically simulated to investigate influence of pressure pulsation on their flow control characteristics. Shunt valves are subjected to pressure variation since ventricles enclosing the brain are under pressure pulsation rather than uniform pressure due to blood pressure variation. We modeled flow orifice through shunt valve and imposed pulsating pressure and valve diaphragm movement to compute flow through the valve. The results of our study indicated that flow rate increased by $40{\%}$ by introducing pressure pulsation and diaphragm movement on the shunt valve. Our results demonstrate the pressure-flow control characteristics of shunt valves unplanted above human brain may be quite different from the characteristics obtained by syringe pump test with uniform pressure and no diaphragm movement.

• Journal of Advanced Marine Engineering and Technology
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• 제22권5호
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• pp.635-642
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• 1998

In automobile exhaust system. Internal pressure pulsation and shell vibration greatly affect the surface sound radiation. This noise is emitted from the muffler outer shell due to the pulsation of the exhaust gas pressure. This paper describes an analytical study of these characteristics as influenced by exhaust system structure. An exhaust simulator was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was identified by finding FRF.

• 신재생에너지
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• 제10권4호
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• pp.9-15
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• 2014

In this study pressure and shaft torque pulsation were measured with variation of head and flow during the model test for a 15 MW Francis Turbine. Pressure pulsations were measured at the inlet of the spiral casing and 4 points in the cone of the diffuser and shaft torque pulsation at the upper position of the turbine. The maximum amplitude of pressure pulsation appeared 2.03% of the maximum rated head with the frequency of 25% of the rated revolution and at the guide vane opening of $10^{\circ}$. Shaft torque pulsation appeared 0.01% of the rated shaft torque, fairly low value. Air was admitted through the cone and pressure pulsation gradually decreased with increase of air flow and kept nearly constant after 5% of the rated flow. A new Francis turbine of which specific speed is 115 m-kW had been designed to rehabilitate the old one and the model test was performed at EPFL. The commercial code, STAR-$CCM^+$ was used for numerical simulation of flow.

• 대한의용생체공학회:의공학회지
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• 제26권4호
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• pp.193-197
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• 2005

Shunt valves used to treat patients with hydrocephalus were tested to investigate influence of intracranial pressure pulsation on their flow control characteristics. Five commercial shunt valves were tested in the flow loop that simulates pulsed flow under pressure pulsation. As 20cc/hr of flow rate was adjusted at a constant pressure, application of $40mmH_2O$ of pressure pulse increased the flow rate by $67.9\%.$ As a 90cm length catheter was connected to the valve outlet, increase in the flow rate was substantially reduced to $17.5\%.$ As the flow rate was adjusted to 40cc/hr at a constant pressure, increase in the flow rate was $51.1\%$ with the same pressure pulsation of $40mmH_2O$. The results indicated that pressure-flow control characteristics of shunt valves implanted above human brain ventricle is quite different from those obtained by syringe pump test at constant pressures right after manufacture. The influence of pressure pulsation was observed to be more significant at low flow rate and the flexibility of the outlet silicone catheter was estimated to significantly reduce flow increase due to pressure pulsation.

• 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.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.1020-1028
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• 2021

The nuclear reactor coolant pump transferring heat energy inherently brings with it the unsteady flow and inevitably threatens to the safe operation of the pump unit, especially with the pressure pulsation induced by the rotor-stator interaction. In this paper, the characteristics of pressure pulsation of the diffuser in a nuclear reactor coolant pump were investigated by the numerical simulation with experimental validation. Pressure pulsation signals measured synchronously from sensors mounted on the radial diffuser of a model pump were analyzed via Welch's method. Frequency components induced by the rotor-stator interaction can be revealed by the diameter mode analysis method. The pressure pulsation of the diffuser is dominated by the blade passing frequency and its harmonics, which are free from the effect of flow rate and rotational speed while the corresponding amplitudes are easily affected by different operational conditions and measuring positions. The non-uniformity is much more affected by the rotational speed than the flow rate. This research is helpful for further work to reduce the pressure pulsation for the reactor coolant pump.