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고분자물질(高分子物質) 첨가(添加)에 따른 마찰저항감소(摩擦抵抗減少)에 관한 연구(硏究)
김재근,차경옥,최형진,김종보,Kim, J.G.,Cha, K.O.,Choi, H.J.,Kim, C.B. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.2
It is well known that drag reduction in single phase liquid flow is affected by polymer material, molecular weight, polymer concentration, pipe diameter, and flow velocity. Drag reduction in two phase flow can be applied to the transport of crude oil, phase change system such as chemical reactor, pool and boiling flow, and to present cavitation which occurs in pump impellers. But the research of drag reduction in two phase flow is not sufficient. The purpose of the present work is to evaluate the drag reduction by measuring pressure drop, void fraction, mean liquid velocity, and turbulent intensity whether polymer is added in the horizontal two phase system or not. Experiment has been conducted in a test section with the inner diameter of 24mm and the length of 1,500mm. The polymer materials used are two kinds of polyacrylamide[PAAM] and co-polymer[A611P]. The polymer concentration was varied with 50, 100 and 200 ppm under the same experimental conditions. Experimental results showed that the drag reduction of co-polymer is higher than that of polyacrylamide. Mean liquid velocities increased as polymer was added, and turbulent intensity decreased inversely near the pipe wall.
김재근(J.G.Kim),이민호(M.H.Lee),유병구(B.G.You),양희준(H.J.Yong),차경옥(K.O.Cha) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.6_2
Drag reduction in polymer solutions is the phenomenon where by extremely dilute solutions of high molecular weight polymers exhibit frictional resistance to flow much lower than the pure solvent This effect, largely unexplained as yet, has attracted the attention of polymer scientists and fluid flow specialists. Although applications are beginning to appear, the principle interest to data has been in attempting to relate the effect to the fluid mechanics of turbulent flow. Also we want to is to evaluate the drag reduction in horizontal flow by measuring pressure drop, mean liquid velocity, and turbulent intensity. Polyacylamide and co-polymer are used for various polymer conditions. Experimental results show higher drag reduction using co-polymer then using polyacrylamide and faster degradation using polyacrylamide than using co-polymer under the same Reynolds number. Mean velocities increase as adding more polymer, and turbulent intensities decrease as the distance for the wall in inversed.<br/>
김재근(J.G.KIM),이준서(J.S.LEE),양희준(H.J.Yong),차경옥(K.O.Cha) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_1
Twisted tape ratio swirl generators have been to be effective in increasing single phase and boiling heat transfer coefficients and in suppressing the critical heat flux in boiling equipments. But the phenomenon are greatly complicated with turbulence, vortex mixing effect, buoyance action, and secondary circulation. Many investigations have been made to determine the presser drop and heat transfer characteristics for single phase flow in tape generated swirl flow. But few studies have been carried out to investigate the heat transfer in two component, two phase swirl flow with non-boiling. An experimental study has been conducted to determine the effects of tape twist ratios on two phase convective heat transfer coefficients, pressure drop, and void fraction distribution in a non-boiling, air-water, two phase flow, the flow conditions were both swirl and non swirl flows. This study has concluded that no significant difference in void fraction distribution were observed both isothermal and nonisothermal conditions, the pressure drop for two phase flow with twisted tape swirler increase as the tape twist ratio decrease, and that values of two phase heat transfer coefficients increase when the tape twist ratio decreases.<br/>