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회전 사각유로에서 냉각유체의 유출량이 열전달에 미치는 효과
전윤흥(Yun Heung Jeon),김상인(Sang In Kim),김경민(Kyung Min Kim),이동현(Dong Hyun Lee),조형희(Hyung Hee Cho) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
The present study investigates the effects of bleed flow on heat/mass transfer in a rotating square channel. The hydraulic diameter (Dh) of the channel is 40.0 ㎜ and the diameter of the bleed holes (d) on leading surface is 4.5 ㎜. The tests were conducted under the condition of various bleed flow rates (0%, 10%, 20%) and rotation numbers (0, 0.2, 0.4), where Reynolds number was fixed at 10,000. A naphthalene sublimation method was employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy. A numerical calculation was conducted to analyze the flow patterns of the internal flow. The results suggests that the heat/mass transfer characteristics in internal cooling passages are influenced by bleed flow and Coriolis force induced by rotation. The heat/mass transfer on leading surface is more increased than without bleed flow, while that on trailing surface is a little decreased due to the diminution of the internal flow.
유출유동을 가진 회전사각유로 내 열/물질전달에 45도 요철이 미치는 영향
전윤흥(Yun Heung Jeon),박석환(Suk Hwan Park),김경민(Kyung Min Kim),이동현(Dong Hyun Lee),조형희(Hyung Hee Cho) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The present study investigated the effects of channel rotation and bleed flow on heat/mass transfer in a square channel with 45° rib turbulators. The bleed holes were located between the rib turbulators on the leading surface and those on the trailing surface case by case. The tests were conducted under the conditions of various bleed ratios (0.0, 0.2, 0.4) and rotation numbers (0.0, 0.2, 0.4) at Re=10,000. The results suggested that heat/mass transfer characteristics were influenced by the Coriolis force, decrement of main flow rate, secondary flow by angled ribs and bleed hole location. As the bleed ratio (BR) increased, heat/mass transfer decreased on both surfaces due to the reduction of main flow rate. With increment of the rotation number, heat/mass transfer also decreased except the trailing surface with bleed holes because the reattachment of the secondary flow induced by angled ribs was weakened on the leading surface and the secondary flow was disturbed on the trailing surface by the Coriolis force.
윤남건(Namgeon Yun),김경민(Kyung Min Kim),전윤흥(Yun Heung Jeon),이동현(Dong Hyun Lee),조형희(Hyung Hee Cho),김문영(Moon Young Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Numerical analyses are carried out in order to understand complex thermal characteristics of a gas turbine combustor liner such as combustion gas temperatures, wall temperatures and heat transfer distributions. As results, The maximum internal and external heat transfer is 2218W/㎡K and 2358W/㎡K, respectively. The combustion gas temperatures range is 673K to 1760K. A range of temperature on TBC is 676K to 1382K. Lastly, temperature range on outer surface of combustion liner cooled by compressed air is 676K to 1188K.
회전 사각유로 내 후연면에 유출유동이 열/물질전달에 미치는 영향
박석환(Suk Hwan Park),전윤흥(Yun Heung Jeon),김경민(Kyung Min Kim),이동현(Dong Hyun Lee),조형희(Hyung Hee Cho) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The present study investigates the effects of bleed flow on heat/mass transfer in a rotating square channel with transverse rib turbulators. The bleed holes are located between the rib turbulators and are installed on leading or trailing surface. The tests were conducted under the conditions of various bleed flow rates (0%, 20%, 40%) and rotation numbers (0, 0.2, 0.4), where Reynolds number was fixed at 10,000. The results suggest that the heat/mass transfer characteristics in the internal cooling passage are influenced by rib turbulators, bleed flow rate and bleed hole location. The heat/mass transfer on the surface with bleed holes is more increased than that without bleed flow, while that on the opposition surface is a little decreased. It is because of the diminution of the internal flow. The results also show that effects of bleed flow is different according to bleed holes location.
90도 요철이 설치된 회전덕트에서 유출홀이 열/물질전달에 미치는 영향
박석환(Suk-Hwan Park),전윤흥(Yun Heung Jeon),김경민(Kyung-Min Kim),이동현(Dong-Hyun Lee),조형희(Hyung Hee Cho) 한국유체기계학회 2005 유체기계 연구개발 발표회 논문집 Vol.- No.-
The present study investigates the effects of bleed flow on heat/mass transfer and pressure drop in a rotating channel with transverse rib turbulators. The hydraulic diameter (Dh) of the square channel is 40.0 ㎜. The bleed holes are located between the rib turburators on leading surface and the hole diameter (d) is 4.5 ㎜. The square rib turbulators are installed on both leading and trailing surfaces. The rib-to-rib pitch is 10.0 times of the rib height (e) and the rib height-to-hydraulic diameter ratio (e/Dh) is 0.055. The tests were conducted at various rotation numbers (0, 0.2, 0.4), while the Reynolds number and the rate of bleed flow to main flow were fixed at 10,000 and 10%, respectively. The results suggest that the heat/mass transfer characteristics in the internal cooling passage are influenced by rib turbulators, bleed flow and the Coriolis force induced by rotation. For the rotating ribbed passage with bleed flow, the heat/mass transfer on the leading surface is hardly affected by bleed flow, but that on the trailing surface decreases due to the diminution of main flow. The results also show that the friction factor decreases with the bleed flow.
회전하는 사각덕트 유로에서 벽면 유출홀에 따른 열전달 특성변화(Ⅰ) - 회전수 변화에 따른 영향 -
김상인(Sang In Kim),김경민(Kyung Min Kim),이동현(Dong-Hyun Lee),전윤흥(Yun Heung Jeon),조형희(Hyung Hee Cho) 대한설비공학회 2005 설비공학 논문집 Vol.17 No.10
The present study has been conducted to investigate convective heat/mass transfer in the cooling passage with bleed holes. The rotating square channel has 40.0 ㎜ hydraulic diameter and the bleed holes on the leading surface of the channel. The hole diameter of bleed hole is 4.5㎜ and its spacing is (p/d=4.9) about five times of hole diameter. Exit mass flow rate through bleed holes is 10% of the main mass flow rate and rotation number is changed form 0.0 to 0.4. A naphthalene sublimation technique is employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy. The cooling performance is influenced by exit mass flow rate through bleed holes and Coriolis force of rotating channel for fixed Reynolds number. The heat transfer on the leading surface is decreased due to Coriolis force. However the total heat transfer is enhanced around holes on the leading surface because of trapping flow by bleeding.