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설계 조건에서 작동하는 축류 팬 주위 익단 누설 유동의 큰 에디 모사
박근태(Keuntae Park),최해천(Haecheon Choi),최석호(Seokho Choi),사용철(Yongcheol Sa) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
An axial fan with a shroud generates complicated vortical structures by the interaction of the axial flow with the fan blades and duct near the blade tips. Large eddy simulation (LES) is performed for flow through a forward-swept axial fan, operating at the design condition of Re = 547,000 based on the radius of blade tip and the tip velocity. The present study predicts the mean values of the flow and head coefficients quite well as compared with the experimental measurements. It is found that two unsteady vortical structures are formed near the blade tip: the tip leakage vortex (TLV) and vortex ropes. The TLV is initiated near the leading edge, develops downstream, and impinges on the pressure surface of the next blade, where the pressure fluctuations and turbulence intensity become high. Vortex ropes are initiated at the aft part of the blade and they merge with TLV.
축류 팬의 공력 성능과 소음 성능을 향상시키기 위한 케이싱 펜스의 적용
박근태(Keuntae Park),최해천(Haecheon Choi),최석호(Seokho Choi),사용철(Yongcheol Sa) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
A casing fence is a newly proposed casing treatment to enhance the aerodynamic and aeroacoustic performances of the axial flow fan that exhausts air into the atmosphere for cooling and ventilation. In the present study, the fence is applied on the shroud near the trailing edge of an axial flow fan used in an outdoor unit of an air conditioner operating at the design condition. The Reynolds number of the fan is 547,000 based on the radius of the blade tip and the tip velocity. We simulate turbulent flows and acoustic fields in the fan using large eddy simulation (LES) coupled with Ffowcs-Williams Hawkings (FW-H) equations. From the numerical simulations with the casing fence, the efficiency of the fan is increased by about 9.5% and the propagating noise is reduced by 0.5dB (A) compared with those without the fence. The fence decreases backflows induced by the tip-leakage vortex near the casing, suppressing the circumferential development of the tip-leakage vortex from the previous blade to the next blade. Also, it reduces the double-leakage tipclearance flow generated at the trailing edge of the blade tip. As a result, the blockage effect by the leakage flow is reduced and the efficiency is increased, and pressure fluctuations on blade surfaces due to the tip-leakage vortex are reduced, resulting in a reduction of the propagating noise.
신기종 전륜 8속 자동변속기 인풋샤프트의 비틀림 피로 수명 평가에 대한 연구
박민서(Minseo Park),심현(Hyun sim),송현근(Hyunkeun Song),허재행(Jaehaeng Heo),박근태(Keuntae Park) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11
The Input shaft of the front-wheel 8 speed automatic transmission(A/T) is one of the key components of the driving system that drives the vehicle by receiving engine power for the first time inside the A/T, and it is also one of the most weakness components since the torque converter transmits peak torque generated by the engine suction-compression-explosion-exhaust cycle. The new front wheel 8 speed A/T, developed by the company, first applied the existing integrated input shaft as separation type for the purpose of downsizing including shortening the entire length according to the customers request. The purpose of this study is to analyze the correlation between structural differences and fatigue damage index by evaluating the fatigue life of the input shaft through a single torsional fatigue durability evaluation for the new 8 speed A/T input shaft.
양계 사료첨가제로서 감태 추출 부산물로 인한 체중증가 및 방어효능 평가
박소연,김정요,박보경,김기주,박근태,한종권,한태욱,Park, Soyeon,Kim, Chung Yoh,Park, Bokyoung,Kim, Kiju,Park, Keuntae,Han, Jong Kwon,Hahn, Tae-Wook 대한수의학회 2016 大韓獸醫學會誌 Vol.56 No.4
The Ecklonia cava Kjellman by-product (ECBP) as a feed additive was evaluated in improvement of productivity and immune enhancement against Salmonella Gallinarum (SG). Lohmann Brown chickens proved SG-free were randomly divided into 3 groups of 8 chickens each. Chickens were fed with the experimental diet treatment: T0, Non treatment-commercial feed; T1, commercial feed with 0.5% ECBP; T2, commercial feed with 0.1% Lactobacillus plantarum. In this study, we evaluated the effect of T1 and T2 groups on the body weight and protective efficacy against SG in chickens. The results demonstrated that treatment of T1 group as a feed additive affected significantly body weight gaining in chickens. In addition, T1 group showed a significant different colonization of SG when compared to T2 and T0 groups. We also studied that serum IgG and $interferon-{\gamma}$ levels were significantly different compared with other treatment groups. Therefore, we suggest that ECBP can be used as a good candidate of feed additives in chicken industry.
계범준(Beomjun Kye),박근태(Keuntae Park),최해천(Haecheon Choi),이명성(Myungsung Lee),김주한(Joo-Han Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In a centrifugal pump, due to its complicated geometry and flow phenomena, an accurate prediction of flow features is a challenging task. In the present study, large eddy simulation is performed to investigate the flow in a centrifugal pump including the impeller and the volute. A dynamic global model (Lee et al., 2010) is used for a subgrid-scale model, and an immersed boundary method is adopted in a non-inertial reference frame (Kim & Choi, 2006) to impose the no-slip boundary condition on stationary and rotating surfaces. The pump performances computed are in good agreements with those by experiments. The instantaneous flow fields indicate that recirculation zones are generated on the pressure and suction surfaces of impeller blades and near the volute tongue. Also, notable amounts of backflow and leakage flow are observed near the impeller outlet and the volute casing.
윤원혁(Wonhyuck Yoon),박근태(Keuntae Park),오세형(Sehyeong Oh),최해천(Haecheon Choi),이명성(Myungsung Lee),김주한(Joo-han Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Flow structures in a cross-flow fan at Re = 5400 based on the blade chord length and the tip velocity at the outer radius are investigated using large eddy simulation with an immersed boundary method. An eccentric vortex near a stabilizer, reverse flow between an impeller and the stabilizer, flow separation on blade suction surfaces, and a recirculation region at the corner of inflow region are observed from simulations. To analyze the effects of these flow structures on the fan performance, the variation of the torque coefficient of each blade in the azimuthal direction is examined. Consequently, the flow separation on the blade suction surfaces produces oscillatory variations of the torque coefficient along the azimuthal direction, causing degraded fan performance. Moreover, the recirculation region is shown to produce a considerable loss and the blades nearby suffer from high torque.