• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3092-3097
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• 2007

Although noise of a RAC can be reduced effectively by decreasing RPM, condensation problems can occur to reduce reliability of the RAC for low RPM. Thus, this research has been performed to propose a design guideline of the RAC for low-noise RPM with high reliability. The internal and external flows of the RAC have been visualized and analyzed by a PIV technique to solve the condensation problem at an outlet and impeller. Then, the design guideline has been proposed by the analyzed results and confirmed by wind-tunnel and noise tests to reduce the condensation problem. Finally the shapes of the outlet with reduced condensation problem and the impeller with low noise have been obtained in this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.569-569
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• 2014

The interior vehicle noise due to the exterior aerodynamic field is an important topic in the acoustic design of a car. The air flow detached from the A-pillar and impacting the side windows are of particular interest as they are located close to the driver / passenger and provides a lower insulation index than the trimmed car body parts. This paper presents a numerical analysis method for a simplified vehicle model. The internal air cavity including trim component are included in the simulation. The car body includes the windshield and two side windows. The body is made of aluminum and trimmed with porous layers. The methodology proposed in this paper relies on two steps: the first step involves the computation of the exterior flow and turbulence induced non-linear acoustic field using CFD Code. The second step consists in the computation of the vibro-acoustic transmission through the window using the finite element vibro-acoustic solver Actran.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.849-855
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• 2015

A better flow condition for the intake of pump is provided by the sump pump that connects the forebay to the intake of the pump station. If the suction sump is improperly shaped or sized, air-entraining vortices or submerged vortices may develop. These phenomena may greatly affect pump operation if vortices become sufficiently large. Moreover, any remaining vortices in the pump flow passage may result in an increase in the noise and vibration of the pump. Therefore, the vortices in the pump flow passage must be reduced to achieve good pump sump station performance. In this study, the effect of suction pipe leaning angle on the pump sump's internal flow is investigated. Additionally, a pipe type with an elbow shape is investigated. The results show that the air entraining vortices occur under the condition of a water level ratio H/D = 1.31 for each suction pipe type.

• Journal of KSNVE
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• v.8 no.1
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• pp.171-179
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• 1998

The present paper deals with the dynamic stability and vibration suppression of a cantilevered flexible pipe having a tip mass under an internal flowing fluid. The equations of motion are derived by energy expressions using extended Hamilton's principle, and some analytical results using Galerkin's method are presented. Finally, the vibration suppression technique by means of an internal fluid flow is demonstrated experimentally.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.856-862
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• 2010

In this paper, the power flow analysis(PFA) method was developed to predict the vibrational responses of coupled co-planar orthotropic plates in frequencies ranging from medium to high. To cover the power transmission and reflection at the joint of the orthotropic plates, the wave transmission approach is applied with the assumption that all the incident waves are normal to the joint. Through numerical analyses, the power flow energy density and intensity fields of coupled co-planar orthotropic plates were compared with those of classical modal solutions by changing the frequency and internal loss factor, and they show good agreement in terms of the global decay and the attenuation patterns of the energy density.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.911-916
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• 2003

A method for the dynamic analysis of thin-walled cylindrical shell conveying steady fluid flow presents. The dynamics of thin-walled shell is based on Sanders' theory and the fluid flow in cylindrical shell is treated inviscid, incompressible fluid. A dynamic coupling conditions at fluid-structure interface is used. The equations of motion are solved by a finite element method and validated by comparing the natural frequency with other published results and Nastran. The influence of fluid velocity on the frequency response function is illustrated and discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.466-471
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• 2014

The interior vehicle noise due to the exterior aerodynamic field is an important topic in the acoustic design of a car. The air flow detached from the A-pillar and impacting the side windows are of particular interest as they are located close to the driver / passenger and provides a lower insulation index than the trimmed car body parts. This paper presents a numerical analysis method for a simplified vehicle model. The internal air cavity including trim component are included in the simulation. The car body includes the windshield and two side windows. The body is made of aluminum and trimmed with porous layers. The methodology proposed in this paper relies on two steps: the first step involves the computation of the exterior flow and turbulence induced non-linear acoustic field using PowerFlow. The second step consists in the computation of the vibro-acoustic transmission through the window using the finite element vibro-acoustic solver Actran. Additionally in order to validate the numerical process, an experimental set-up has been created based on the simplified vehicle. The vibration of the windshield and windows, the total wind noise level results and the relative contributions of the different windows are then presented and compared to measurements. The influence of the flow yaw angle (different wind orientation) is also assessed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.291-291
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• 2013

The interior vehicle noise due to the exterior aerodynamic field is an important topic in the acoustic design of a car. The air flow detached from the A-pillar and impacting the side windows are of particular interest as they are located close to the driver / passenger and provides a lower insulation index than the trimmed car body parts. HMC is interested in the numerical prediction of this aerodynamic noise generated by the car windows with the final objective of improving the products design and reducing this noise. The methodology proposed in this paper relies on two steps: the first step involves the computation of the exterior flow and turbulence induced non-linear acoustic field using the CAA(Computational aeroacoustics) solver CAA++. The second step consists in the computation of the vibro-acoustic transmission through the side window using the finite element vibro-acoustic solver Actran. The internal air cavity including trim component are included in the simulation. In order to validate the numerical process, an experimental set-up has been created based on a generic car shape. The car body includes the windshield and two side windows. The body is made of aluminum and trimmed with porous layers. First, this paper describes the method including the CAA and the vibro-acoustic models, from the boundary conditions to the different components involved, like the windows, the trims and the car cavity is detailed. In a second step, the experimental set-up is described. In the last part, the vibration of the windshield and windows, the total wind noise level results and the relative contributions of the different windows are then presented and compared to measurements. The influence of the flow yaw angle (different wind orientation) is also assessed.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.112-121
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• 2024

The pipping system is widely used in many industries as equipment for transporting fluids over long distances. In high-pressure pipe, as the speed of the fluid increases, a loud noise is generated. Therefore, various studies have been conducted to reduce pipe noise. In this paper, a pipe noise analysis was developed to predict and quantitatively assess the flow-induced vibration and acoustic-induced vibration due to valve flow in high-temperature and high-pressure. To do this, a high-fidelity fluid analysis technique was developed for predicting internal flow in the pipe with valve. In additional, the contribution of compressible/incompressible pressure by frequency band was evaluated using the wavenumber-frequency analysis. To predict a low/middle frequency pipe noise, the vibroacoustic analysis method was developed based on Finite Element Method (FEM). And the pipe noise prediction method for the middle/high frequency was developed based on Statistical Energy Analysis (SEA).

• Journal of KSNVE
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• v.8 no.6
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• pp.1053-1061
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• 1998

In this paper. the power flow analysis(PFA) method is applied to the prediction of the vibrational energy density and intensity of coupled co-planar plates. To cover the energy transmission and reflection at the joint of the plates. the wave transmission approach is Introduced with the assumption that all the incident waves are normal to the joint. By changing the frequency ranges and internal loss factors. we have obtained the reliable PFA results. and compared them with the analytical exact solutions.