• 한국음향학회지
• /
• 제43권1호
• /
• pp.112-121
• /
• 2024

배관시스템은 유체를 장거리로 이송시키는 장비로서 많은 산업군에서 사용되고 있다. 고압의 배관에서는 빠른 유속으로 인하여 소음이 크게 발생하고 있으며, 이러한 소음을 저감 시키기 위한 많은 연구가 수행되고 있다. 이 논문에서는 고온·고압의 배관내 밸브 유동을 원인으로 발생하는 유동유발진동과 음향유발진동을 설계단계에서 예측하고 정량적으로 분석을 위한 배관 소음 해석 기법을 개발하였다. 이를 위하여 배관의 내부 유동 예측을 위한 고정밀 유동 해석기법을 개발하였으며, 파수-주파수 분석법을 이용하여 주파수 대역별 압축성/비압축성 압력의 기여도를 평가하였다. 그리고 유한요소 해석법(Finite Element Method, FEM)을 기반으로 한 저·중 주파수 대역의 진동소음 해석기법을 개발하였으며, 통계적 에너지 분석법(Statistical Energy Analysis, SEA)을 기반으로 한 중·고 주파수 대역에서의 방사소음해석 기법을 개발하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.404-409
• /
• 2004

A compressor loop pipe is the most important part in a refrigerator from the view of structural vibration and noise. Vibration energy generated from a compressor's inner body is transmitted to the shell and outside through the loop pipe. For this reason it is very important to design a compressor loop pipe. But, for geometrical complexity and dynamic nonlinearity of the loop pipe, analysis and design of the loop pipe is very difficult. So the statistical and experimental methods have to be used for design of this system. The response surface method (RSM) becomes a popular meta-modeling technique f3r the complex system as this loop pipe. As starting point of loop pile's optimization, FEA model and simple experimental model are used instead of the real loop pipe model. After RS model was constructed, using sensitivity-based optimizer performed optimization for the loop pipe. And the moving least square method (MLSM) was applied to reduce the approximation error.

• 한국소음진동공학회논문집
• /
• 제18권11호
• /
• pp.1177-1184
• /
• 2008

URN(underwater radiated noise) is one of the important performances of the battle ship related to the stealth. The main source of the URN is the structure-borne noise on the hull. And the pipe vibration transmitted to the hull is the main source of the structure-borne noise when the speed of the ship is lower than CIS(cavitation inception speed). In this paper, the vibration isolator(rubber mount) for the pipe system is described in order to reduce the structure-borne noise transmitted to the hull. The vibrations on the sea-water conveying pipes and their supports are measured in order to know how much vibration occurs on those positions. Based on these test results, the improved design of the rubber mount is suggested by the parametric study and is verified numerically with the pipe and hull model.

• 한국소음진동공학회논문집
• /
• 제12권5호
• /
• pp.374-379
• /
• 2002

A new active muffler system has been developed and its superior performance on both noise reduction and engine torque increase is demonstrated with experiment. Main characteristic of the proposed muffler system is the use of destructive interference by transmission path difference of divided exhaust pipes to reduce major exhaust noise components thereby overcoming problems of other active exhaust noise control methods. The exhaust pipe is divided into two sections and joined again downstream. One divided pipe has a sliding mechanism to vary its length, which is controlled to make half wavelength transmission path difference for the major engine rpm frequency. In this system one divided pipe is used to control major rpm frequency and its Harmonics and another pipe is used to control noise component double the frequency of rpm. An after-market tuning muffler, which has very simple internal structure and minimal back pressure, is also installed to remove remaining wideband noise. To make the system to be small enough to be practical, conventional muffler is also installed and used in low rpm range and active muffler is only employed in high rpm range. Noise reduction of the proposed system is comparable to conventional passive muffler. The engine dynamo test has proved the proposed system can recover almost all the torque lost by conventional muffler.

• 한국소음진동공학회논문집
• /
• 제12권7호
• /
• pp.550-556
• /
• 2002

The vibrational system of this study is consisted of a cantilever pipe conveying fluid. the moving mass upon it and an attacked tip mass. The equation of motion is derived by using Lagrange equation. The influences of the velocity and the inertia force of the moving mass and the velocities of fluid flow in the pipe haute been studied on the dynamic behavior of a cantilever pipe by numerical method. As the velocity of the moving mass increases, the deflection of cantilever pipe conveying fluid is decreased. Increasing of the velocity of fluid flow make the amplitude of cantilever pipe conveying fluid decrease. The deflection of the cantilever pipe conveying fluid is increased by moving masses. After the moving mass passed upon the cantilever pipe, the amplitude of pipe is influenced due to the deflection of pipe tilth the effect of moving mass and gravity.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 춘계학술대회 논문집
• /
• pp.679-680
• /
• 2011

The Forced vibration characteristics of elastically restrained pipe conveying fluid with the attached mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Hamilton's principle. The effect of attached mass and spring constant on forced vibration of pipe system is studied. Also, the critical flow velocities and stability maps of the valve-pipe system are obtained as each parameters.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
• /
• pp.67-71
• /
• 2003

The propagation characteristics of the impulse wave discharged from the exit of a perforated pipe is investigated through a simple shock tube facility. The pressure histories and directivities of the impulse wave propagating outside from the exit of pipe with several different configurations are analyzed for the range of the incident weak shock wave Mach number between 1.02 and 1.2. In the shock tube experiments, the impulse wave are visualized by a Schlieren optical system for the purpose of understanding its propagation characteristics. The experimental results show that for the near sound field the impulse noise strongly propagates toward to the pipe axis, but for the far sound field the impulse noise uniformly propagates toward to the omnidirections, indicating that the directivity pattern is almost same regardless of the pipe type. Especially, it is shown that the perforated pipe has a little performance to reduce the impulse noise only for the near sound field

• 한국추진공학회지
• /
• 제7권3호
• /
• pp.15-21
• /
• 2003

본 연구에서는 다공관의 출구로부터 전파하는 충격성 소음의 전파특성을 실험적으로 파악하였다. 다공관은 공극율, 구멍지름 그리고 관의 길이를 각기 다르게 제작하여 충격파 관 출구에 부착하여 실험하였다. 충격파 전파마하수는 실제의 적용조건을 참고하여 1.02-1.2의 범위로 하였다. 지향성은 근음장과 원음장으로 구분하여 측정하였다. 또한 충격성 소음원인 펄스파의 전파과정을 조사하기 위하여 쉴리렌 광학장치를 이용하였다. 실험결과로부터 다공관의 소음저감 성능은 음장조건에 좌우됨을 알았다. 즉 근음장 조건에서는 다공관의 공극율과 관의 길이가 소음저감에 다소간의 영향을 미치지만, 원음장 조건에서는 다공관이 충격성 소음의 저감에 거의 기여하지 못하였다. 이와 같이 음장조건에 따라 충격성 소음의 저감성능이 다르게 되는 것은 근음장 조건에서는 관축방항으로 강한 지향성을 보이지만, 원음장 조건에서는 모든 방향으로 같은 세기로 전파하는 무지향성이기 때문이다.

• 한국기계가공학회지
• /
• 제8권1호
• /
• pp.71-76
• /
• 2009

In a running blower, there are various exciting forces which can generate noise. The noise of an running industrial fan or blower depends on the structure of a fan, the machining accuracy of each element, and assembled conditions. Many studies have been carried out to reduce the noise of it. In this study, 3-hole buffs are used in pipe of blower to study the influence the number and position of buffs on the noise reduction at inlet and outlet in pipe. Commercial engineering software ANSYS and SYSNOISE were employed to analyze the characteristics and reduction ratio of pressure. It is concluded that optimal position and number of buffs in pipe of blower to show the least reduction ratio of pressure.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 춘계학술대회논문집
• /
• pp.308-311
• /
• 2005

In this paper, we studied about the effects of the rotating cantilever pipe conveying fluid with a moving mass. The influences of a rotating angular velocity, the velocity of fluid flow and moving mass on the dynamic behavior of a cantilever pipe have been studied by the numerical method. The equation of motion is derived by using the Lagrange's equation. The cantilever pipe is modeled by the Euler-Bemoulli hew theory. When the velocity of a moving mass is constant, the lateral tip-displacement of a cantilever pipe is proportional to the moving mass and the angular velocity. In the steady state, the lateral tip-displacement of a cantilever pipe is more sensitive to the velocity of fluid than the angular velocity, and the axial deflection of a cantilever, pipe is more sensitive to the effect of a angular velocity.