• 한국기계가공학회지
• /
• 제9권1호
• /
• pp.19-24
• /
• 2010

The noise of an running industrial fan or blower depends on the type of a fan, the machining accuracy and assembled conditions of each element, and buffs. Many studies have been carried out to reduce the noise through silencer in blower. In this study, 3 types of buffs which have different hole are employed in pipe of blower to study the influence the number and arrangement of buffs on the noise reduction at inlet and outlet in pipe. Commercial engineering software ANSYS was employed to analyze the characteristics and reduction ratio of pressure. Experimental results shows that optimal one can reduce the reduction ratio of noise as much as 16 percents in the laboratory. Good agreement was found between the analysed ratio of noise reduction and those obtained from the experiments.

• 한국산학기술학회논문지
• /
• 제15권7호
• /
• pp.4659-4664
• /
• 2014

산업 현장에서 발생하는 소음은 작업자의 건강과 작업 효율에도 영향을 줄 뿐 아니라, 주변의 주거지역의 소음 민원의 원인이 된다. 본 논문에서는 중소규모 공장에서 많이 사용되는 송풍기에서 발생하는 소음을 3차원 공간에서 능동소음제어기(ANC)를 이용하여 저감하는 기술 개발을 위한 기초 연구를 수행하였다. 이를 위해 ANC의 설정과 결과 데이터를 용이하게 파악할 수 있는 시뮬레이터 프로그램을 Labview를 이용하여 작성하여 음압레벨, 스펙트럼, 등가소음도 등의 데이터를 비교하였다. 소음 데이터는 현재 중소규모 공장에서 운전 중인 터보팬 송풍기에서 발생하는 소음을 기기 주변 17개의 위치에서 녹음하여 사용하였다. 모의실험 결과 17 지점 모두 500Hz 이하 저주파 대역에서 파워 스펙트럼이 최대 40dB 줄었으며 등가소음레벨이 평균 12.6dB 감쇄되는 결과를 보였다.

• 한국자동차공학회논문집
• /
• 제12권6호
• /
• pp.158-165
• /
• 2004

The DC motor in a vehicle may cause noise and vibration because of high speed revolution, which can make a driver feel uncomfortable. There have been various studies attempting to solve these problems, focusing mostly on the causes of and ways to reduce noise and vibration. It is suggested that the noise in a DC motor may be primarily due to interaction between a brush and a commutator. Brush noise, the most common noise in a DC motor, results from a brush bounced from the surface of the commutator, fluctuation of the friction between the brush and the commutator, and the impact on the brush when passing over slots of the commutator. Based on the noise test, one of the most important design parameters was shown to be the roundness of the commutator. As the DC motor is used, the roundness of the commutator gets bigger with subsequent increase of the level of brush noise and vibration. There must be a threshold in order to prevent the brush noise from getting worse. Using the method of CAE is more efficient than the real test for purposes of looking for various design parameters to maintain the roundness of the commutator. In this study, the design process to reduce the brush noise is presented with the use of a computer model. The design parameters to reduce the brush noise and vibration are proposed by using FEM. The design parameters are used to reduce the noise and vibration of a DC motor and it is verified with the test results on a fan DC motor in a vehicle. This method may be applicable to various DC motor.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.961-966
• /
• 2001

Micro fans of randomly swept-blades were designed to provide C.P.U. in a personal computer with effective cooling in a very quiet mode. The proto--type axial micro-fans machined by a laser sintering machine were tested against manufactured products by comparing the performance and overall sound pressure level with spectral measurements in an environment suggested by ASHRAE and ANSI standards. The predicted OSPLs and directivity patterns of fans by iDesignFan software were in good agreements with measured data. The newly introduced fans of randomly swept-blades were proved to provide a very promising mode of low noise at small loading conditions.

• 한국소음진동공학회논문집
• /
• 제21권4호
• /
• pp.339-345
• /
• 2011

The purpose of this study is reduction the vibration of the personal computer by developing the vibration absorber and damper. The eccentricity of the cooling fan causes the vibration of the computer. We designed the material properties of the vibration absorber and damper by FEM model within operation frequencies of the cooling fan. We experiment the overall analysis and system analysis by using a laser vibrometer. The result shows that the proposed dynamic absorber and damper reduce the vibration of the personal computer.

• Journal of Advanced Marine Engineering and Technology
• /
• 제24권4호
• /
• pp.509-514
• /
• 2000

A numerical study has been performed to design duct parameters in the freezer of a domestic refrigerator. The visualization results of FDM analysis using the standard k-$\varepsilon$ model with inlet boundary conditions modelled in this paper show good agreements with the experimental ones in prediction overall flow characteristics. Dominant vortex flows are found in the left upper and right lower corners, while there exists large turbulent kinetic energy around the fan and right upper side of the fan. It, in turn, has effects on the performance and noise. It is recommended to locate the outlet far away from the fan in order to reduce the noise level.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
• /
• pp.116-122
• /
• 2002

It is addressed that the turbulent broadband sound power from a sirocco fan can be modeled by the trailing edge noise. The trailing edge noise is usually influenced by inflow turbulenca separation, and boundary layer thickness on the blade. The design parameters such as solidity (c/s) and stagger angle are specified to predict performance and noise level because the separation and slip velocity are strongly affected by them along with the flow coefficient. This paper reports the effects of the stagger angle upon the trailing edge noise for various trailing edge shapes. It is believed that the serrated trailing edge provides break-up mechanism for organized convecting vortices, thereby reduce the overall noise level for every case of stagger angle.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 추계학술대회논문집
• /
• pp.208-211
• /
• 2006

Flow resistance induced by each element in suction nozzle of a vacuum cleaner with a rotary fan is investigated numerically and its relation with flow-induced noise is examined. Flow resistance and vorticity in suction nozzle are calculated and it is found that they are closely related with flow-induced noise. From numerical results, it is suggested that reduction of flow resistance effectively increases all-suction performance and decreases sound pressure level of noise generated in the suction nozzle.

• 한국유체기계학회 논문집
• /
• 제6권3호
• /
• pp.7-14
• /
• 2003

It is addressed that the turbulent broadband sound power from a sirocco fan can be modeled by the trailing edge noise. The trailing edge noise is usually influenced by inflow turbulence, separation, and boundary layer thickness on the blade. The design parameters such as solidity (c/s) and stagger angle are specified to predict performance and noise level because the separation and slip velocity are strongly affected by them along with the flow coefficient. This paper reports the effects of the stagger angle upon the trailing edge noise for various trailing edge shapes. It is believed that the serrated trailing edge provides break-up mechanism for organized convecting vortices, thereby reduce the overall noise level for every case of stagger angle.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
• /
• pp.137-142
• /
• 2000

The turbulent broadband sound power from a forward curved bladed fan can be modeled by the trailing edge noise. The trailing edge noise is usually influenced by inflow turbulence, separation, and boundary layer on the blade. This paper reports the effects of the solidity (C/s) and the stagger angles upon the trailing edge noise with respect to the trailing edge shapes of circular-arc cambered blade of multi-bladed fan, and discusses the major physical mechanism of reduced noise lot the circular trailing-edged case.