• Title/Summary/Keyword: Pipe flow noise

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Reduction of Refrigerant-induced Noise of the Refrigerator by Modification of the Evaporator Inlet Pipe (증발기 입구 배관의 구조 개선을 통한 냉장고 냉매 소음 저감)

  • Kim, Min-Seong;Han, Hyung-Suk;Kim, Tae-Hun;Jeong, Wei-Bong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.10
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    • pp.1012-1020
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    • 2009
  • This research is focused on the experimental study of the noise induced by two-phase refrigerant flow in the evaporator. The two-phase flow in the evaporator has various flow patterns. The effects of two-phase flow pattern's characteristics on the noise of the evaporator are investigated experimentally. The experimental data shows that the generated noise is mainly related to the layout of the pipe and the certain two-phase flow patterns such as the churn and slug flow. Based on these results, we removed the unnecessary vertical pipe and changed the pipe diameter of the evaporator - inlet into small one in order to avoid the intermittent flow condition. The noise level of newly-designed inlet-pipe of the evaporator was measured experimentally by refrigerant-supplying equipment and compared with that of conventional one.

A study on the Prediction of the Radiated Noise by Fluid Induced Vibration in the pipe (배관의 표면진동을 이용한 소음예측기법 연구)

  • Yi, Jongju;Pak, Kyunghyon;Jung, Woojin;Seo, Youngsoo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.04a
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    • pp.609-614
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    • 2014
  • This study is on the experiment of the pipe noise due to the internal fluid. The straight pipe, the $90^{\circ}$ mitred pipe, rounded $90^{\circ}$ and $1350^{\circ}$ pipe were tested and measured the vibration and noise. In the experiment, the vibration and noise level of the straight pipe and rounded pipes show that the vibration and noise level are almost same. The $90^{\circ}$ mitred pipe shows the high vibration and noise level. In the prediction of noise due to the internal flow, the use of pipe surface vibration and radiation efficiency shows good agreement with experiment result.

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A Study on the Radiated Noise the Prediction in the Pipe by Fluid Induced Vibration using the Radiation Efficiency and Pipe Surface Vibration (배관 표면진동과 방사효율을 이용한 배관 소음예측기법 연구)

  • Yi, Jongju;Park, Kyunghoon;Jung, Woojin;Seo, Youngsoo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.10
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    • pp.763-769
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    • 2014
  • This study is on the experiment and prediction of the pipe noise due to the internal fluid. The vibration of pipe external surface and noise in air were measured according to the internal fluid velocity and pipe type. In the experiment, the vibration and noise level of the straight pipe and rounded pipes show that the vibration and noise level are almost same. The 900 mitred pipe shows the high vibration and noise level. In the prediction of noise due to the internal flow, the method using the pipe surface vibration and radiation efficiency shows good agreement with experimental result.

Reduction of Fire Main Pipe System's Vibration Using Back Flow Prevent Globe Valve (역류방지 글로브 밸브를 이용한 소화 주관계의 진동개선)

  • Park, Mi-You;Han, Hyung-Suk;Lee, Seuk-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.518-523
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    • 2009
  • Main source of URN(Underwater Radiated Noise) which is related to the ship's survivability is divided into two groups. Cavitation is main source of URN when the speed of ship is upper than CIS(Cavitation Inception Speed). But when the speed of ship is lower than CIS, main source of URN is structure-borne noise on the hull which is originated from propulsion system, pump system or transmitted vibration of pipe system. In this paper, to reduce the vibration of discharge pipe and valve system, back flow prevent globe valve and new rubber mount are applied to the ship. As the result of applying new valve and mount, the vibration is reduced drastically.

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Reduction of Fire Main Pipe System's Vibration Using Back Flow Prevent Globe Valve (역류방지 글로브 밸브를 이용한 소화 주관계의 진동개선)

  • Park, Mi-You;Han, Hyung-Suk;Lee, Seuk-Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.6
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    • pp.599-606
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    • 2009
  • Main source of URN(underwater radiated noise) which is related to the ship's survivability is divided into two groups. Cavitation is the main source of URN when the speed of ship is upper than CIS(cavitation inception speed). But when the speed of ship is lower than CIS, the main source of URN is the structure-borne noise on the hull which is originated from propulsion system, pump system and trnasmitted vibration of the pipe system. In this paper, to reduce the vibration of discharge pipe and valve system, back flow prevent globe valve and new rubber mount are applied to the ship. As the result of applying new valve and mount, the vibration is reduced drastically.

Reduction of the Refrigerant-Induced Noise from the Transition of Flow Pattern by Decreasing Tube Diameter

  • Takushima, Akira;Han, Hyung-Suk;Jung, Wei-Bong
    • International Journal of Air-Conditioning and Refrigeration
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    • v.17 no.2
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    • pp.37-44
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    • 2009
  • It is well known that a refrigerant-induced noise is caused by two-phase flow in the indoor unit of a heat pump air-conditioner. Especially when the flow pattern in a pipe is intermittent flow, the irregular noise occurs frequently. But it is very difficult to avoid this kind of the noise for the application of air-conditioner. Therefore, in this research, the flow patterns at two-phase flow state in a pipe of the indoor unit for the air-conditioner are researched using cycle simulator at typical cycle conditions. In order to find the relationship between refrigerant-induced noise and flow pattern, the noise patterns are investigated with respect to the estimated flow pattern from the various flow pattern maps. Base on the estimations of the flow patterns by those maps, the refrigerant-induced noise is evaluated as decreasing tube diameter, which can transit the flow pattern from slug to annular flow.

An Experimental Study on the Propagation of Impulse Noise in the Far Sound Field (원음장에서의 충격성 소음전파에 관한 실험적 연구)

  • 송화영;제현수;이주원;이성태;이동훈
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.852-855
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    • 2004
  • This experimental study describes the propagation characteristics of the impulse noise emitted from the exit of a straight pipe attached to the open end of a simple shock tube. The sound pressure level and directivity of the impulse noise propagating from the exit of pipe with several different diameters are measured in the far sound fold for the range of the incident shock wave Mach number between 1.07 and 1.26. The experimental results showed that the peak values of impulse noises had a strong dependance on the exit diameter of a pipe and the shock wave Mach number. The impulse noise had the directivity propagating toward to the pipe axis and the characteristics of inverse square law of propagation distance. Moreover, it was shown that the one-third octave band SPL of impulse noise was almost constant regardless of the frequency band.

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Development of numerical method to predict broadband radiation noise resulting in fluid-induced vibration and acoustic-induced vibration of pipe (배관의 유동 유발 진동 및 음향 유발 진동 기인 광대역 방사 소음 예측을 위한 수치 해석 기법 개발)

  • Sangheon Lee;Cheolung Cheong;Songjune Lee
    • 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).

Influence of Tip Mass on Stability of a Rotating Cantilever Pipe Conveying Fluid (유체유동 회전 외팔 파이프의 안정성에 미치는 끝단질량의 영향)

  • Son, In-Soo;Yoon, Han-Ik;Kim, Dong-Jin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.10
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    • pp.976-982
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    • 2007
  • In this paper the vibration system is consisted of a rotating cantilever pipe conveying fluid and tip mass. The equation of motion is derived by using the Lagrange's equation. The system of pipe conveying fluid becomes unstable by flutter. Therefore, the influence of a rotating angular velocity, mass ratio, the velocity of fluid flow and tip mass on the stability of a cantilever pipe by the numerical method are studied. The critical flow velocity for flutter is proportional to the angular velocity and tip mass of the cantilever pipe. Also, the critical flow velocity and stability maps of the pipe system are obtained by changing the mass ratios.

Improvement of an Ultrasonic Transducer for Measuring Both Flow Velocity and Pipe Thickness (유속 및 파이프 두께 측정 겸용 초음파 트랜스듀서 개선)

  • Kim, Ju Wan;Kim, Jin Oh
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.2
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    • pp.148-156
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    • 2016
  • The paper deals with improvement of a piezoelectric ultrasonic transducer for measuring both pipe thickness and flow velocity. The transducer structure is based on the conventional transducers for measuring flow velocity by obliquely transmitting ultrasonic waves to the flow direction. The transducer invented earlier for measuring flow velocity and pipe thickness had an advantage of including only one piezoelectric disc, but for the thickness measurement the ultrasonic wave had to be reflected twice in a wedge material to be transmitted vertically to a pipe, and thus the wave signal was too weak. The transducer has been improved to transmit waves for thickness measurement vertically to a pipe without any prior reflection by electrically connecting two piezoelectric discs, one for flow velocity and the other for pipe thickness measurement. By comparing the measured results of specimen thickness with the improved transducer and conventional transducers, the accuracies of the improved one have been evaluated in the pipe thickness measurements.