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김진욱(Jin Wook Kim),김동범(Tongbeum Kim),송성진(Seung Jin Song) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Although compressor blades have long been shrouded for aerodynamic and structural reasons, the importance of the leakage flow in the shrouded axial compressor has been investigated recently. However, the effects of the leakage tangential velocity variation on the blade passage flow are unknown. Therefore, this paper reports on an experimental investigation of the loss and flow turning in the blade passage in shrouded axial compressor cascades subject to the variation of the leakage tangential velocity. The newly found results are as follows. First, increasing the leakage tangential velocity reduces overall loss up to 32.6% compared to the reference case. Second, increasing the leakage tangential velocity spreads loss core in the pitch-wise direction. Thus, loss core becomes more two-dimensional. Third, increasing the leakage tangential velocity makes the near hub passage flow more radially uniform.
슈라우드 축류압축기에서 누수접선방향속도가 블레이드 구간 유동에 미치는 영향
김진욱(Jin Wook Kim),손대웅(Dae Woong Sohn),김동범(Tongbeum Kim),송성진(Seung Jin Song) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
Although compressor blades have long been shrouded for aerodynamic and structural reasons, the impact of the leakage flow in the shroud cavities on passage flows has only recently been investigated. Furthermore, the tangential velocity of the leakage flow, set by the blading and the relative motion between rotating and stationary surfaces, has a strong influence on the passage flow. Yet the influence of the tangential velocity variation on the main flow in the blade passage are unknown. Therefore, this paper reports on an experimental investigation of the axial evolution of loss generation in the blade passage in shrouded axial compressor cascades subject to the variation of leakage tangential velocity. The newly found results are as follows. First, increasing tangential velocity of the leakage flow reduces loss at 10% and 50% chordwise locations in the passage. However, most of the blockage and loss reductions occurs in the aft half chord and downstream of the blade passage. Second, the increasing tangential velocity spreads the loss core, which is originally concentrated in the suction side hub corner, in the pitchwise direction. Thus, the loss core becomes more two-dimensional, and the region's radial extent is reduced. Third, increasing tangential velocity of the leakage flow makes the near hub passage flow more radially uniform. Consequently, the shear and resultant mixing loss between the passage and leakage flows are reduced near the hub, reducing the overall loss.
축류압축기 슈라우드 캐비티내의 누수유동 경로에 대한 연구
손대웅(Dae Woong Sohn),김동범(Tongbeum Kim),송성진(Seung Jin Song) 한국유체기계학회 2005 유체기계 연구개발 발표회 논문집 Vol.- No.-
Measurements of the leakage flow in the shrouded cavity were performed in axial compressor cascades at Re=2.6×10?. This paper describes the effects of the leakage flow tangential velocity on kinematics of the leakage flow in the shrouded cavity and consequent overall loss and exit flow turning at stator blade row downstream. Flow data and flow visualization images consistently indicate that leakage flow circumferentially migrates 2, 4 and 5 blade passages in the direction of rotation for υy/c=0.09, 0.35 and 0.45, respectively where υy is the leakage tangential velocity and c is the mainstream velocity. The leakage flow contracts to a jet across the seal-tooth resulting in an increase in the leakage axial velocity-doubling the leakage axial velocity in upstream cavity compared to that in the downstream cavity. Consequently, two flow regions are distinguished before and after the seal-tooth. As increasing the leakage tangential velocity, the overall loss downstream of stator blade row decreases and the exit flow turning in the range of span from the hub endwall to 15% increases while the decreases in the flow turning from 15% to 30% span is observed.
이재석(Jae Seok Lee),김진희(Jin Hee Kim),김동범(Tongbeum Kim),송성진(Seung Jin Song) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-
The effects of flow interaction between mainstream and shrouded cavity leakage flow in an axial-flow compressor on aerodynamic losses are experimentally and numerically examined. A fraction of mainstream is ingested in the downstream cavity and travelled in the shrouded cavity along the direction opposite to the mainstream. This leakage flow is caused by adverse pressure gradient along the blade passage. Then it is entrained through the upstream cavity near mid-pitch and interacts with the mainstream. As a result, the convection flow angle with respect to the blade chord is reduced i.e. underturning This underturned flow results in an increase in size of secondary flow formed near the suction side of the blade as well as its magnitude. Consequently, this causes pronounced increase in overall aerodynamic losses compared to the blading without shrouded cavity, leading to 9% decrease in pressure rise through the single stage of the stators.