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진동 신호를 이용한 블로워 모터 틱/클릭과 톤 소음의 진단 지수 개발
이송준,정철웅,이인혁,Lee, Songjune,Cheong, Cheolung,Lee, In-Hyuk 한국음향학회 2019 韓國音響學會誌 Vol.38 No.3
복잡한 회전 기계의 소음 상태 진단을 위한 다양한 연구가 수행되고 있다. 본 연구에서는 진동신호를 이용하여 블로워 모터의 효율적이고 객관적인 소음 상태진단을 위한 지수를 개발하였다. 블로워 모터의 이상 시 가장 흔히 나타나는 소음으로 틱/클릭 소음과 톤 소음이 있다. 발생 원인과 소음 특성에 따라 틱/클릭 소음의 상태 진단에는 시간-주파수 분석법을 그리고 톤 소음 상태 진단에는 주파수 영역에서의 평활화 기법을 이용하였다. 개발한 지수를 이용하여 블로워 모터의 소음 상태 진단을 수행하고 이를 전문가에 의한 진단 결과와 비교하였다. 그 결과 약 95 %의 일치율을 보였다. Various studies have been conducted for the diagnosis of noise condition of complex rotary machines. In this study, diagnosis index using vibration signal is developed for the efficient and objective assessment of noise condition of a blower motor. The noise most commonly caused by the abnormal blower motor are Tick/Click noise and Tone noise. According to cause and noise characteristics, time-frequency analysis is used to diagnose Tick/Click noise, and smoothing in frequency domain is used to diagnose tone noise condition. The noise condition of the blower motors were diagnosed using the developed index and these results are compared with the diagnostic results by the experts. As a result, the agreement rate was about 95 %.
격자 볼츠만 방법을 이용한 덕트 내 쌍둥이 직렬배열 사각 실린더에 의한 Aeolian 순음소음 고찰
이송준(Songjune Lee),정철웅(Cheolung Cheong) 한국소음진동공학회 2014 한국소음진동공학회 논문집 Vol.24 No.12
The lattice Boltzmann method(LBM) has attracted attention as an alternative numerical algorithm for solving fluid mechanics since the end of the 90’s. In these days, its intrinsic unsteadiness and rapid increase in computing power make the LBM be more applicable for computing flow-induced noise as well as fluid dynamics. The lattice Boltzmann method is a weakly compressible scheme, so we can get information about both aerodynamics and aeroacoustics from single simulation. In this paper, numerical analysis on Aeolian tone noise generated by tandem-twin square cylinders in duct is performed using the LBM. For simplicity, laminar two-dimensional fluid models are used. To verify the validity and accuracy of the current numerical techniques, numerical results for the laminar duct and the cylinder flows are compared with the analytical solution and the measurement, respectively. Then, aerodynamic noise of the twin tandem square cylinders is investigated. It is shown that the aerodynamic noise from the twin tandem square cylinders can be reduced by controlling the distance between the cylinders.
격자 볼츠만법을 이용한 자동차 뒷 창문 버페팅 소음 특성해석
이송준(Songjune Lee),최형규(Hyunggyu Choi),조문환(Munhwan Cho),이강덕(Kang-duck Ih),정철웅(Cheolung Cheong) 한국소음진동공학회 2015 한국소음진동공학회 논문집 Vol.25 No.10
Buffeting noise through a rear window in an automobile is investigated by using lattice Boltzmann method. The generation mechanism of the buffeting noise can be understood as the resonance mechanism in a Helmholtz resonator, which is driven by the convecting vortex in a shear-layer flow over the neck of the resonator. Two methods to suppress the buffeting noise are proposed, and their effects are quantitatively assessed. Opening front window reduces the observed buffeting tonal noise by 25 dB and the overall SPL by 4 dB, and the installation of a Helmholtz resonator acting as a dynamic damper reduces the tonal component that by 35 dB and the overall SPL by 10 dB.
파수-주파수 분석을 이용한 자동차 옆 창문 표면 압력 섭동의 비압축성/압축성 성분 분해
이송준(Songjune Lee ),정철웅(Cheolung Cheong) 한국소음진동공학회 2016 한국소음진동공학회 논문집 Vol.26 No.7
The vehicle interior noise caused by exterior fluid flow field is one of critical issues for product developers in a design stage. Especially, turbulence and vortex flow around A-pillar and side mirror affect vehicle interior noise through a side window. The reliable numerical prediction of the noise in a vehicle cabin due to exterior flow requires distinguishing between the aerodynamic (incompressible) and the acoustic (compressible) surface pressures as well as accurate computation of surface pressure due to this flow, since the transmission characteristics of incompressible and compressible pressure waves are quite different from each other. In this paper, effective signal processing technique is proposed to separate them. First, the exterior flow field is computed by applying computational aeroacoustics techniques based on the Lattice Boltzmann method. Then, the wavenumber-frequency analysis is performed for the time-space pressure signals in order to characterize pressure fluctuations on the surface of a vehicle side window. The wavenumber-frequency diagrams of the power spectral density shows clearly two distinct regions corresponding to the hydrodynamic and the acoustic components of the surface pressure fluctuations. Lastly, decomposition of surface pressure fluctuation into incompressible and compressible ones is successfully accomplished by taking the inverse Fourier transform on the wavenumber-frequency diagrams.
격자 볼츠만법을 이용한 단순 확장형 소음기 음향특성 해석
이송준(Songjune Lee),이광세(Gwang-Se Lee),정철웅(Cheolung Cheong) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10
The Lattice Boltzmann Method (LBM) has attracted attention as an alternative numerical algorithm for solving fluid mechanics, and its intrinsic unsteadiness and weak numerical damping make it more suitable for aeroacoustic problems. In this paper, applicability of the LBM for solving flow noise problems is tested by applying it to predict transmission loss of a simple expansion silencer. The time history of the static pressure is recorded at the inlet and outlet pipes. The transmission loss (TL) of the muffler is computed by using three point method and two source method, respectively. The TL calculated using the LBM is compared with that computed using finite element method (FEM) and measured data. It is found through these comparisons that the LBM is capable of predicting TL of the simple expansion silencer accurately, which it is difficult to predict using the conventional CFD methods based on the RANS solvers.