Department News
Investigation of Three-Dimensional Unsteady Flows in a Two-Stage Shrouded Axial Turbine
Seminar Date
2005-11-16
Author
임아주
Date
2005-11-15
Views
1802
1. 제 목 : Investigation of Three-Dimensional Unsteady Flows in a Two-Stage Shrouded Axial Turbine
2. 연 사 : YONG IL YUN (윤용일)
School of Mechanical and Aerospace Engineering
Seoul National University, Seoul, Korea
3. 일 시 : 2005년 11월 16일(수) 오후 4시~
4. 장 소 : 301동 1221호
5. 내 용 : This thesis presents an experimental study of the behavior of leakage flow across shrouded turbine blades. Stereoscopic particle image velocimetry and fast response aerodynamic probe measurements have been conducted in a low-speed two-stage axial turbine with a partial shroud. Within the shroud cavity, two vortical flows are developed: one is a vortex shed at the second shroud knife tip and the other is a vortex due to flow separation at the shroud trailing edge. The latter is a unique structure in the current partially shrouded turbine. Initially the vortex is generated with tangential vorticity and axial vorticity is generated via tilting of the tangential vorticity.
Downstream of the shroud cavity, three layers (the seal leakage layer, cavity flow layer, and main flow) are formed. This result is different from the two layer structure which is found downstream of conventional shroud cavities. The seal leakage jet formed through the seal clearance still exists at 25.6 percent axial chord downstream of the second rotor. This delay of complete dissipation of the seal leakage jet and its mixing with the cavity flow layer is due to the contoured casing wall. The three layer structure forms two skewed shear layer and the axial vorticity generated within the cavity interacts with these skewed shear layer. Due to this interaction, mixing is enhanced.
Time-averaged flow downstream of the shroud cavity shows the upstream stator’s influence on the cavity flow. The time-averaged main flow can be viewed as a wake flow induced by the upstream stator whose separation at the shroud trailing edge induces pitchwise non-uniformity of the cavity flow. Thus, it is concluded that the partially shrouded rotor geometry effect combined with the contoured casing determines the spanwise variation of flow parameters while the upstream stator’s effect is more important in determining the pitchwise non-uniformity of the cavity flow layer.
6. 문 의 : 기계항공공학부 송 성 진 교수 (☎880-1667)
2. 연 사 : YONG IL YUN (윤용일)
School of Mechanical and Aerospace Engineering
Seoul National University, Seoul, Korea
3. 일 시 : 2005년 11월 16일(수) 오후 4시~
4. 장 소 : 301동 1221호
5. 내 용 : This thesis presents an experimental study of the behavior of leakage flow across shrouded turbine blades. Stereoscopic particle image velocimetry and fast response aerodynamic probe measurements have been conducted in a low-speed two-stage axial turbine with a partial shroud. Within the shroud cavity, two vortical flows are developed: one is a vortex shed at the second shroud knife tip and the other is a vortex due to flow separation at the shroud trailing edge. The latter is a unique structure in the current partially shrouded turbine. Initially the vortex is generated with tangential vorticity and axial vorticity is generated via tilting of the tangential vorticity.
Downstream of the shroud cavity, three layers (the seal leakage layer, cavity flow layer, and main flow) are formed. This result is different from the two layer structure which is found downstream of conventional shroud cavities. The seal leakage jet formed through the seal clearance still exists at 25.6 percent axial chord downstream of the second rotor. This delay of complete dissipation of the seal leakage jet and its mixing with the cavity flow layer is due to the contoured casing wall. The three layer structure forms two skewed shear layer and the axial vorticity generated within the cavity interacts with these skewed shear layer. Due to this interaction, mixing is enhanced.
Time-averaged flow downstream of the shroud cavity shows the upstream stator’s influence on the cavity flow. The time-averaged main flow can be viewed as a wake flow induced by the upstream stator whose separation at the shroud trailing edge induces pitchwise non-uniformity of the cavity flow. Thus, it is concluded that the partially shrouded rotor geometry effect combined with the contoured casing determines the spanwise variation of flow parameters while the upstream stator’s effect is more important in determining the pitchwise non-uniformity of the cavity flow layer.
6. 문 의 : 기계항공공학부 송 성 진 교수 (☎880-1667)
