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축류 가스터빈내 동익의 허브면에 장착된 경계층 펜스의 효과에 대한 수치 해석적 연구
윤덕규(Deok-Kyu Yoon),이우상(Wu Sang Lee),김대현(Dae Hyun Kim),정진택(Jin Taek Chung) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
The objective of this study is to investigate the effects of the boundary layer fence equipped on the hub of the rotor in an axial gas turbine which occurs the interaction between the stator and rotor. The complicate three-dimensional flows in an axial gas turbine cause secondary loss and increase the total pressure loss. In order to reduce or control these secondary flows, the boundary layer fence which has the height of one third of the inlet boundary layer thickness was equipped on the hub of the rotor. This study was performed numerically. The result shows that wake generated by the stator reduces the development of secondary flow in the rotor blade passage but doesn't interrupt the formation of horseshoe vortex generated in front of the rotor blade leading edge. Although boundary layer fence gives rise to additional loss, it can reduce total pressure loss compared to the case without fence by enervating downstream secondary vortices.
자유유동 난류강도가 터빈 캐스케이드내 3차원 난류유동 특성에 미치는 영향에 관한 전산해석
윤덕규(Deok-Kyu Yoon),이우상(Wu Sang Lee),김대현(Dae Hyun Kim),정진택(Jin Taek Chung) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
The objective of this study is to determine the influence of free-stream turbulent intensity on the three-dimensional turbulent flow in a linear turbine cascade. The range of free-stream turbulence intensity considered is 0.7~10%. This study was performed numerically. The results show that the mass averaged loss coefficient increased according to the increase of free-stream turbulence intensity due to increased value of the mass averaged total pressure loss coefficient which was higher than the decreased value of the mass averaged secondary flow loss coefficient. The loss coefficient distribution was changed suddenly at a free-stream turbulence intensity of 10% while the loss coefficient distribution was rarely changed at a lower free-stream turbulence intensity of 5%.
1단 축류 터빈의 정익/동익 상호작용하에서 축 간격에 따른 동익내 열전달 특성에 관한 수치해석
윤덕규(Deok Kyu Yoon),이우상(Wu Sang Lee),김대현(Dae Hyun Kim),정진택(Jin Taek Chung) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The objective of this study is to investigate the heat transfer characteristics on the rotor blade with the wake from the stator in an axial turbine stage which has the interaction between the stator and rotor blade. This study was performed numerically and dimensionless St number to represent the degree of heat transfer was calculated on the hub, shroud and blade suction surface as the distance variation between stator and rotor blade. The results show that heat transfer on the hub and blade suction surface was decreased as the distance between stator and rotor blade increases because the wake from the stator was decreased by friction on the hub, shroud and the passage vortex in the rotor stage. When the wake from the stator run into the leading edge of the rotor, the heat transfer on the suction surface occurred the most actively; however, heat transfer near the trailing edge was little decreased by the flow separation.
끝벽의 형상이 터빈 캐스케이드 내열전달 특성에 미치는 영향에 관한 전산해석
이우상(Wu sang Lee),윤덕규(Deok kyu Yoon),곽현주(Hyun ju Kwag),정진택(Jin Taek Chung) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
The Objective of this study is to document the three-dimensional flow in a turbine cascade with Contoured endwall in terms of Stanton number distribution to proposes an appropriate contraction ratio of endwall contouring which show the best performance. This study was numerically performed. The results show that heat transfer coefficient on the contoured endwall which has the height of 15% of the axial chord showed best performance. The numerical method and results in this study can be applied to the design of gas turbine cascade with high performance.
세그먼트 스퀼러팁을 갖는 터빈블레이드의 특성에 대한 수치해석
김대현(Dae Hyun Kim),김재춘(Jae Choon Kim),윤덕규(Deok Kyu Yoon),정진택(Jin Taek Chung) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
The purpose here is to explore a little further into characteristics of squealer and segment squealer tip. Tip leakage flow is caused by damage of blade tip between shroud and blade tip. Gas turbine blade install groove or rim to reduce the thermal stress in blade tip. But internal cavity of turbine blade squealer tip isdifficult to cooling. Squealer tip come out crack for a long work time. To reduce thermal stress of squealer tip set up segment at Squealer tip crack place of radial direction. Thermal stress for leakage flow is dependent on temperature and pressure conditions. And squealer tip find out crack positions. In addition, squealer tip is instituted segment at crack position. Consequently, Squealer tip and Segment Squealer tip are a lot of difference. Each of segments are absorbed heat and pressure.