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나인(Md. J. Nine),이경환(G. H. Lee),정효민(H. M. Jeong),정한식(H. S. Chung) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The article represents an experimental investigation on pressure drop and friction loss behaviors of free airflow through a rectangular duct fitted with semicircular ribs of uniform height on one principle wall. The aspect ratio of the rectangular duct is AR= 5, duct height was of H= 30 ㎜ and uniform rib heights (e = 3.5 ㎜m) were used for three different rib pitches of 30 mm, 35 ㎜ and 42 ㎜. For this cases, the rib height to hydraulic diameter ratio were e/D = 0.07 and rib height to channel height ratio were e/H = 0.11. The experimental results show some significant effects of static pressure near the wall and at various configurations and different numbers of rib arrangements within test section. Each result is compared with another among different configurations of rib arrangement over the 90 ㎝ X 15 ㎝ copper plate test section. The Reynolds number in the inlet of calculation domain was in a range of 10000 to 30000. Digital micro manometer and pressure transducer were used for taking static pressure of this experiment. Darcy friction factor was used and isothermal pressure drop had been considered in data evaluation. These experiment will be the preliminary investigation for turbulence analysis as heat transfer enhancement using periodic semicircular ribs.
열교환기 표면 거칠기에 의한 난류 모델의 유동 특성 비교
이경환(Gyeonghwan Lee),나인(Md. J. Nine),최순호(Soonho Choi),정효민(Hyomin Jeong),정한식(Hanshik Chung) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
A numerical analysis of flow characteristics on the roughed rectangular duct for turbulent flow has been carried out. The aspect ratio of the rectangular duct was AR=5, the rib height to hydraulic diameter ratio were 0.07 and rib height to channel height ratio were e/H=0.11. The v2-f turbulence model and SST k- ω turbulence model were used for the modified near-wall function which are suited for realistic phenomena. The numerical analysis results show turbulent flow characteristics and pressure drop at the near the wall as observed experimentally. The results predict that turbulent kinetic energy k is closely relative to the diffusion of recirculation flow. and v2-f turbulence model's simulation results have a good agreement with experiment.