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에어컨 실외기 홴의 강풍(역풍)조건하에서의 신뢰성 평가에 대한 해석적 연구
송우석(Woo-Seog Song),김병건(Byung-Ghun Kim),길성호(Seong-Ho Kil),이창선(Chang-Seon Lee) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
Sometimes damaged fans by the storm or hurricane have been reported in the air-conditioner industry. High-speed reverse rotating of the fan caused by the external force from strong winds, especially without-driving condition. In this paper, a numerical analysis procedure to evaluate the reliability of the high-speed reverse rotating fan in air-conditioner outdoor unit by ultimate exterior flow velocities is proposed. Information of the reverse RPM and pressure distributions of blade surfaces are determined from 3-dimensional CFD analysis method and link directly to the structural analysis method to evaluate the structural stability factors. In addition, the results of this procedure expect to be useful to evaluate the reliability of outdoor unit fan and the suitability of the installing condition for system.
비선형 열원모델을 이용한 Rijke tube 내열음향 불안정 곡선의 수치예측기법
송우석(Woo-Seog Song),이승배(Seungbae Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
The thermal system like a combustion chamber is believed to experience a significant instability problem with vibration in case that the thermal energy or the acoustic energy are transformed into a different form through a relevant path. This study deals with a numerically-predicted, Thermoacoustic instability in a Rijke tube by using a non-linear model for a heat source. The heating part where the energy transformation occurs actively is modeled after simulating two-dimensional cylinder case with constant surface temperature, and a nonlinear model that accounts for the transfer function of magnitude- and phase-characteristics is properly implemented so as to be dependent on the pulsation strength in the tube. The heat source model is observed to result in equivalent Thermoacoustic instabilities in the Rijke tube except low flow-rate cases in which the natural convection is dominant.
송우석(Woo-Seog Song),서형준(Hyeong-Joon Seo),김종문(Jong-Moon Kim),김영재(Young-Jae Kim),서용호(Yong-Ho Seo),주영주(Youngju Joo),황준(Jun Hwang) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.6
In this study, we introduced the improved airflow-direction-control-method without the control-blade using PCM(Pressure Control Method) and the new indoor unit of cassette type air conditioner as its actual application. In order to demonstrate the feasibilities of PCM, we defined the two plane - the pressure difference forming plane, and flow direction control plane - in 2-Dimensional domain and analyzed the control factor and the effect. Because the direct wind of 4-way cassette cause discomfort and is often unable to reach all areas evenly, we developed the circular type cassette by this technology which distribute fast and even airflow in all directions. We examined the thermal comfort index ADPI(Air Diffusion Performance Index) in the residential space about two types. Experimental result shows that circular type is 13% higher than 4-way type due to high-efficiency flow control and even air distribution.
송우석(Woo-Seog Song),신승열(Seungyeol Shin),이승배(Seungbae Lee) 대한기계학회 2012 大韓機械學會論文集B Vol.36 No.11
16채널 어레이 마이크로폰을 이용하여 난류 유동장 내 벽면 압력섭동에 대한 측정을 수행하였다. 본 실험에 사용된 코팅재질은 약 50 ppi (pores per inch)의 다공성 구조로 이루어진 우레탄 물질로 이루어져 있다. 코팅의 주된 목적은 난류 유동장 내 최소한의 공간을 유지하면서 대류속도로 진행하는 난류 와들을 필터링하는 역할을 하는 것이다. 평판 위 경계층의 측정은 열선 유속계를 이용하였으며 표면 마찰계수 값을 얻기 위해 CPM법을 사용하였다. 벽압력 스펙트럼과 파수-주파수 스펙트럼 측정은 코팅에 의해 얼마나 에너지가 저감되는 지를 비교하기 위해 사용되었다. 벽면 코팅은 대류하는 무차원 벽면섭동압력에너지를 저감시켰지만, 컴플라이언트 코팅된 벽면 거칠기로 인해 일반 강체 평판에 비해 상대적으로 발달된 경계층을 형성하였으며 벽면 평균전단응력과 저주파수 압력스펙트럼 레벨도 함께 증가하였다. Fluctuating wall pressures were measured using an array of 16 piezoelectric transducers beneath a turbulent boundary layer. The coating used in this experiment was an open-cell, urethane-type foam with a porosity of approximately 50 ppi. The ultimate objective of the coating is to provide a mechanical filter to reduce the wall pressure fluctuations. The boundary layer on the flat plate was measured by using a hot wire probe, and the CPM method was used to determine the skin friction coefficient. The wall pressure autospectra and streamwise wavenumber-frequency spectra were compared to assess the attenuation of the wall pressure field by the coating. The coating is shown to attenuate the convective wall pressure energy. However, the relatively rough surface of the coating in this investigation resulted in a higher mean wall shear stress, thicker boundary layer, and higher low-frequency wall pressure spectral levels compared to a smooth wall.
박용민,송우석,이승배,Park, Yong-Min,Song, Woo-Seog,Lee, Seung-Bae 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.6
The BEM is a highly efficient method in the sense of economical computation. However, boundary integration is not easy for the complex geometry and moving surface, e.g. a rotating blade. Thus, Kirchhoff surface is designed in an effort to overcome the difficulty resulting from complex boundary conditions. A Kirchhoff surface is a fictitious surface which envelopes acoustic sources of main concern. Acoustic sources may be distributed on each Kirchhoff surface element according to their acoustic characteristics. In this study, an axial fan is assumed to have unsteady loading noise as a dominant source. Dipole sources can be modeled to solve the FW-H equation. Acoustic field is then computed by determining Kirchhoff surface on which near-field is implemented, to analyze the effect of Kirchhoff surface on it. The optimal shape and the location of Kirchhoff surface are discussed by comparing with experimental data acquired in an anechoic chamber.
김진혁(Jin-Hyuk Kim),송우석(Woo-Seog Song),이승배(Seungbae Lee),김광용(Kwang-Yong Kim) 한국유체기계학회 2009 유체기계 연구개발 발표회 논문집 Vol.2009 No.-
This paper presents a procedure for the aerodynamic and aeroacoustic characteristics of sirocco fan. For the aerodynamic and aeroacoustic analyses of sirocco fan, three-dimensional steady state and unsteady Reynolds-averaged Navier-Stokes equations are solved with the shear stress transport turbulence model as a turbulence closure model. Flow analyses are performed on a hexahedral grid through a finite-volume solver. The validation of the numerical results is performed through experimental data for the pressure, efficiency and power. The internal flow analyses of sirocco fan are performed in order to understand the unstable flow phenomenon in casing through the wall pressure and internal flow characteristics at each position. As results of these analyses, it is found that the fluctuations of the pressure value and locally concentrated noise sources are observed near the cut-off and expansion region of casing.
김병국(Byung-Kook Kim),김영호(Young-Ho Kim),송우석(Woo-Seog Song),이승배(Seungbae Lee),남상규(Sang-Kyu Nam),김사만(Sa-Man Kim) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
This paper presents the design procedure of a drag-type, vertical wind turbine named jet-wheel turbine, and the numerical and the experimental verification procedures. The design parameters such as the chord length, the exit angle of inlet guide and side guide vanes, and the rotor blade inlet angle were optimized to minimize the energy loss and increase the effective torque together with the efficiency by considering the effect of the angle of attack. The maximum power coefficient of 0.42 was experimentally confirmed while the maximum power coefficient of 0.5 was predicted based on the numerical simulation. This vertical-axis model can be applied to the large-scale power generation system by the modular design and the control algorithm for the wide range of operation.