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정백조건에 따른 백미의 정백 및 탁도 특성 -주축 송풍속도에 따른 특성-
강태환 ( T. H. Kang ),조병효 ( B. H. Cho ),강신형 ( S. H. Kang ),원진호 ( J. H. Won ),이희숙 ( H. S. Lee ),한충수 ( C. S. Han ) 한국농업기계학회 2016 한국농업기계학회 학술발표논문집 Vol.21 No.2
백미의 품질특성 중 탁도는 쌀을 씻는 과정에서 발생하는 쌀뜨물의 탁한 정도이며, 쌀뜨물은 다량의 유기물을 포함하여 하천으로 유입될 경우 수질오염의 주요 원인이 되고 있다. 따라서 본 연구에서는 정백공정 중 백미의 정백 및 탁도 특성을 분석하기 위하여 중공인 주축 송풍속도에 따른 적정 정백조건을 구명하고자 하였다. 공시재료는 전라북도 김제시에서 생산된 2015년산 신동진 백미를 사용하였고, 정백 중 백미의정백 및 탁도 특성은 주축 송풍속도에 따라 25, 30, 35 m/s의 3수준에서 측정하였다. 1회 시료량은 20 kg을 사용하였고, 백미 가공기계 1, 2단의 회전속도는 각각 1,000 rpm과 1,100 rpm으로 하였으며, 미강을 흡인하기 위한 송풍기의 속도는 1단의 경우 40 m/s, 2단은 31 m/s로 하였다. 또한 가공롤러의 통풍구 수는 1단은 3구, 2단은 4구로 하였으며, 가공롤러의 유도가이드 각도는 1, 2단 모두 0°로 하였다. 주축 송풍속도에 따른 백미의 백도는 큰 영향을 미치지 않는 것으로 판단된다. 정백 후 싸라기율은 주축 송풍속도에 따라 25, 30 및 35 m/s에서 각각 0.99, 1.34, 1.06%로 나타나, 주축 송풍조건에 따른 싸라기율은 큰 차이가 없는 것으로 판단된다. 주축 송풍속도에 따른 가공 전·후 백미의 탁도 감소는 주축 송풍속도가 빠를수록 탁도 감소가 높은 경향을 보였으며, 주축 송풍속도 25 m/s 조건의 경우 15.1 ppm, 30 m/s는 16.8 ppm 탁도가 감소하였고, 주축 송풍속도 35 m/s에서는 탁도가 20.2 ppm 감소하는 것으로 나타났다.
공병진,박다인,변상호,이상호 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.6
Air blower has been widely used in many industrial fields such as wind tunnel and large ventilation systems. Its performance is affected by operating conditions and system geometry of inpeller and duct, and these design parameter optimization is essential for the effective development. CFD analysis is carried out to investigate the air flow field characteristics with outlet total pressure in a blower system. Intake air into the impeller blade through the inlet is compressed, and then gradually discharged from the outlet with ascending total pressure, and predicted results are compared with test data. Especially this overall pressure difference in the blower system severely depends on the flow rate. These results are expected to be used as applicable design data for blower performance improvement.
전용두,이종수 공주대학교 생산기술연구소 2002 論文集 Vol.10 No.-
Cross flow fan system is widely used for various applications, especially for the air-moving device of heaters, air-conditioners, and air-curtains. Although there are efforts for the optimization of cross-flow fan flow path with different methods of approach, it is still being investigated by many researchers through experimentally and/or theoretically, because the flow pattern of the cross flow fan is not stereotyped. This paper presents some results from numerical experiments for optimization of the flow path through a cross-flow fan to be applied to indoor wall-mounted room heater. Two dimensional analysis has been applied to a specific fan system including inlet and diffuser outlet. Flow characteristics are presented and discussed for two different flow path at three different operating conditions represented by rotational speed(800, 1,000, 1,200 rpm) of the fan. According to the simulated results for the specific fan system under consideration, it could be found that the flow pattern resembles each other at different rotational speed (to say from 800 rpm to 1,200 rpm) for a fixed flow path, while the secondary flows mostly absorbs the speed effects. By changing the flow path significant increase in volume flow rate is estimated upto 2.65 at the same rotational speed. According to the present experience, fan flow path design can be performed more efficiently by incorporating this type of numerical experiments combined with the model tests.
Desktop Personal computer 內附의 流動特性에 관한 硏究
이행남(Haeng-Nam Lee),박길문(Gil-Moon Park),정한별(Han-Byul Jung) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
This study speculates flowing at upper edge and slots of a case occurring by fans installed in different axises inside the PC case through PIV(Particle Image Velocimetry). Parasiticalphenomenon occurring inside the PC case decreases efficiency of discharge and causes noise. This study put a particle for tracing inside the case and then a camera recorded the field of flowing of mean time under proper lighting to analyse data on distributions of re-stress, velocity vector and kinetic energy. This study is expected to contribute to resolve many engineering problems such as cooling efficiency of CPU, parasitic phenomenon and noise occurring inside the PC case.
상류 후류의 익렬 유동에 미치는 영향에 대한 실험적 연구
김형주,조강래,주원구,Kim, Hyeong-Ju,Jo, Gang-Rae,Ju, Won-Gu 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.3
This paper is concerned with the effect of cylinder wakes upstream on blade characteristics of compressor cascade(NCA 65 series). At first, it is found that the velocity defect ratio of cylinder wake varies according to the acceleration and deceleration in a flow field but, is conserved nearly constant at flow downstream the cascade, irrespective of the flow path in the cascade. When a cylinder wake flows along near the suction surface of the blade, or impinges on the leading edge, the turbulent velocities are supplied on or inside the outer edge of boundary layer near the leading edge of suction surface, and the transition to a transitional or turbulent boundary layers is induced, so that the laminar separation is prevented, but the profile loss increases. The transition of boundary layer to a transitional or turbulent one is strongly related with the strength of added turbulent velocities near the leading edge on the suction surface, which is influenced by the flow path of a cylinder wake.