• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.675-680
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• 2001

In this study, a fluid/structure coupled analysis system using computational fluid dynamics and computational structural dynamics has been developed. The unsteady flow fields are predicted using unstructured Euler code. Coupled time-integration method (CTIM) was applied to computer simulation of the flow-induced vibration phenomena. To investigate the interaction effect of shock motions, 2-DOF airfoil systems have been studied in the subsonic and transonic flow region. Also, aeroelastic analyses for the airfoil with an arbitrary object are performed to show the analysis capability and interference effects for the complex geometries. The present results show the flutter stabilities and characteristics of aeroelastic responses with moving shock effects.

• 한국소음진동공학회논문집
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• 제16권10호
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• pp.1082-1089
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• 2006

In this study, advanced computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling Independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Wavier-stokes equations with one equation Spalart-Allmaras and two-equation SST ${\kappa}-{\varepsilon}$ turbulence models are solved for unsteady flow problems and also relative moving and vibration effects of the rotor cascade are fully considered. A coupled implicit time marching scheme based on the Newmark integration method is used for computing the governing equations of fluid-structure interaction problems. Detailed vibration responses for different flow conditions are presented and then vibration characteristics are physically investigated in the time domain as computational virtual tests.

• 한국소음진동공학회논문집
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• 제21권5호
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• pp.437-446
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• 2011

Performance of array sonars towed underwater is limited due to the self-noise induced mainly by the strumming vibration of the towing cable and also turbulent flow around the acoustic sensor module. The vibration of the towing cable generates axisymmetric waves that propagate along the acoustic module of the array sonar and produce self-noise. The present study aims to investigate the characteristics of the self-noise induced by the axisymmetric vibrations of the acoustic module. The waves of interest are the bulge and extensional waves propagating along the fluid-filled elastic hose. Dispersion relations of these waves are predicted by means of the numerical simulation to evaluate the wave speeds. The self-noise induced by the axisymmetric waves are formulated taking into account the damping of the elastic hose and the effect of the damping is investigated.

• 소음진동
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• 제11권3호
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• pp.471-476
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• 2001

This paper focuses on the numerical prediction of airflow-induced sound in DVD drives. As a first step, computational fluid dynamics (CFD) is conducted to evaluate flow field characteristics due to the high-speed disk rotation, and to support the acoustic analysis. Acoustic analogy based on Ffowcs Wi1liams-Hawkings (FW-H) equation is adopted to predict aeroacoustic noise patterns. The integral solution for quadrupole volume source is included to identify the turbulence noise generated inside the DVD tray. The strength of sound pressure revel with respect to rotating speed is discussed to meet upfront demand on the high fidelity product development. The present study also focuses on the noise directivity and examines how much the sound noise is sensitive to change in rotating speed. Near-field noise is strongly affected by the flow field characteristic, which is caused by the complex shape of the tray. For a mid-field, the quadrupole noise play as a counterpart of thickness noise or loading noise, so it generates different sound noise Patterns compared with those in the near field.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.680-681
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• 2009

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.785-786
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• 2011

• 한국소음진동공학회논문집
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• 제25권8호
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• pp.532-538
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• 2015

In a reciprocating compressor, highly impulsive pressure fluctuations induced by a reciprocating piston give rise to serious noise and vibration problems. A muffler is frequently used to reduce this impulsive noise, but also has adverse effects on compressor performance due to additional pressure drop and heat transfer of refrigerants through it. Therefore, the flow and acoustic performances of mufflers used in a compressor should be considered simultaneously. In this study, both of flow and acoustic performances of mufflers are investigated using computational fluid dynamic techniques by solving full three-dimensional compressible Reynolds-Averaged Navier-Stokes equations. For validation purpose, the numerical method is initially applied to predict the transmission loss of a simple expansion muffler, and its predicted results show good agreements with theoretical and experimental results. Then, the flow and acoustic performances of an existing muffler is numerically investigated. On the basis of the analysis results, a new muffler is purposed and its performances are compared with the existing one. Improved performances of the new muffler are confirmed.

• 한국산학기술학회논문지
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• 제13권10호
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• pp.4371-4377
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• 2012

본 논문에서는 수도용 감압밸브에서의 유체유발진동의 원인을 파악하기 위한 위하여 구조-유체 연성 해석을 수행하였다. 감압밸브의 소음을 측정한 결과 250Hz의 저주파 대역의 소음이 있음을 확인하였다. 상용 소프트웨어인 ANSYS/CFX를 사용하여 유체의 유동 해석을 수행한 결과, 감압밸브 내에서 노즐 효과에 의하여 40m/s 정도의 유속이 형성되고, 이에 따라 감압밸브 내에 부압이 발생하였다. 밸브 내에 형성된 유동에 의한 압력 분포를 하중 조건으로 구조해석을 한 결과, 유로를 막을 수 있을 정도의 고무 재질인 디스크의 변형이 발생하였다. 이러한 디스크의 변형이 반복적으로 일어남으로써 소음진동현상이 발생함을 확인하였다.

• 한국소음진동공학회논문집
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• 제22권7호
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• pp.619-625
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• 2012

Since the fuel is always exposed to turbulent flow, the grid strap shows flow induced vibration characteristics that impact on the nuclear fuel soundness. The dynamic behavior of grids in nuclear fuels is quite complex, since two pairs of spring and dimple support are contacted with rods by friction in the limited space. This paper focuses on investigation of the grid strap(test fuel strap, TFS) vibration in one cell. TFS consists of a single spring and double dimples. To identify the grid strap vibration, modal analysis of the strap is performed using finite element method(FEM). Modal testing on a $5{\times}5$ grid structure without rods is performed. The modal testing results are compared to analytic results. In addition, random test considering rod effect is performed about a $5{\times}5$ grid with rods under real contact condition in the air. Finally, the strap vibration of a $5{\times}5$ fuel bundle in investigation of flow induced vibration(INFINIT) facility is measured in real fluid velocity condition without heating. It is shown that modal frequencies from the test are almost equal to those peak frequencies in the INFINIT test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.565-568
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• 2014

Hyundai Motor Company is proposing the fourth evolution of their Hyundai Simplified Model as benchmark results for the validation of CFD codes in aeroacoustics and noise transmission to the interior of a cabin. The focus of this benchmark is on variations in noise level induced by small typical geometry changes that can be found in a car development program. This article presents the noise transmission results obtained with PowerFLOW in combination with a SEA model and shows that it is possible to capture small variations in noise level with a lattice Boltzmann method based code.