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오정택(Jeongtaek Oh),위효성(Hyoseong Wi),박진일(Jinil Park),이종화(Jonghwa Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
For more precise analysis of vehicle fuel consumption during experimental driving mode, the measurement of energy loss(pumping friction, mechanical friction, alternator friction and etc.) is performed by pre-experiment. On diesel vehicle, mechanical friction is increased according to engine speed and load increasing. Thus the measurement of mechanical friction on diesel engine usually has performed by engine rig test using a dynamometer. However, for diesel vehicle which is going to be performed driving mode experiment, engine dynamometer test spends much time and effort, because it needs a separate operation from vehicle. In this paper, for more convenient way, chassis dynamometer test is attempted for measuring of mechanical friction for diesel engine on vehicle condition and verified with results of engine dynamometer test and NEDC mode test. Via the chassis dynamometer test, less time and effort can be spent than engine dynamometer.
소음 상사를 이용한 직교류 홴의 유동 소음에 관한 수치해석 연구
이명성(Myungsung Lee),강성원(Seongwon Kang),허남건(Nahmkeon Hur),박정택(Jeongtaek Park) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
The flow noise of a cross-flow fan in an air conditioner indoor unit is investigated by a 2-D CFD simulation and acoustic analogy analysis. Transient flow field is obtained by solving the unsteady Reynolds-Averaged Navier-Stokes equation with the arbitrary sliding interface method to slide the grid for the relative motion of the rotating cross-flow fan. To predict the flow noise generated due to the cross-flow fan, an acoustic analogy analysis is performed with Ffowcs-Williams Hawkings model. The results show the details of transient flow field inside the air-conditioner including the typical eccentric vortex, which is appeared in the vicinity of the stabilizer. The strong interaction between the eccentric vortex and stabilizer is also well predicted, which is well known as the primary factor of the flow noise of the cross-flow fan. In order to validate the present analysis, the numerical result is compared with available experimental data such as the overall sound pressure level.
LES 및 음향상사 모델을 이용한 에어컨 실내기의 공력 소음원에 대한 수치해석적 연구
민윤홍(Yunhong Min),강성원(Seongwon Kang),허남건(Nahmgeon Hur),박정택(Jeongtaek Park) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In the present study, the aerodynamic noise source was analyzed for air-conditioner indoor unit. The 3-D LES was used because the noise prediction using acoustic analogy method requires the accurate flow result in a vicinity of noise source. For 3-D computation, the sound correction method which is derived by Kato was used to take account of longer span length. Since the quadrupole contribution is negligible in subsonic flow of air-conditioner indoor unit, the Farassat formulation 1A which considers only monopole and dipole source was applied to predict far-field acoustic pressure. In air-conditioner indoor unit, the three noise sources are blade and two fan casings. The predicted SPL (Sound Pressure Level) using the three noise sources was good agreement with the experimental data. When the separated vortex interacts with each noise source, the pressure fluctuation on the surfaces causes the main noise in subsonic flow. Especially the blade was dominant source because there were the most active form of interaction between blades and vortex. Also the blade had the effect of BPF (Blade Passing Frequency) peak noise as the specific flow structures in the cross-flow fan.
에어컨 실내기 직교류팬의 공력소음에 대한 소음원의 수치해석적 분석
민윤홍(Yun Hong Min),강성원(Seongwon Kang),허남건(Namkeon Hur),박정택(Jeongtaek Park) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
In the present study, analyze of the noise source was conducted from prediction of aerodynamic noise of cross-flow fan (CFF) in air-conditioner (AC) indoor unit. For accurate prediction of vortex caused the aerodynamic noise, 3-D computation and large eddy simulation (LES) were adopted. The Ffowcs Williams-Hawkings (FW-H) equation, which is one of the acoustic analogy methods for far-field acoustic pressure, was used to predict aerodynamic noise. The sound pressure level (SPL) result of the predicted total noise of AC indoor unit was good agreement with a valid experimental data. The stabilizer, rear guider and blades in AC indoor unit were considered for the main noise source, and each SPL spectra were compared with the tonal noise to analyze the noise source. The dominant component was different as frequency band. Especially, the blade passing frequency (BPF) peak and broadband noise were most affected by the blades. The result also showed flow characteristics caused tonal and broadband noise.