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Seung Ho Cho(조승호),Taehyoun Kim(김태현),Seung Jin Song(송성진) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A few fluid structure interaction analyses have been developed for turbomachinery blades in comparison with aircraft wings. Also, the existing aeroelastic analyses for turbomachinery blades have been mostly limited to cases with a steady freestream. In reality, however, the inflowing freestream is often pulsating. Therefore, this paper presents stability and forced response analyses of an isolated three-dimensional blade under pulsating freestream conditions. A new three-dimensional unsteady vortex lattice model under a pulsating freestream has been developed in discrete time domain to examine unsteady aerodynamic forces acting on a vibrating blade. The blade’s structural behaviors have been analyzed by using a three-dimensional plate model. In the aeroelastic analysis, the flutter onset of a blade under pulsating freestream is predicted by the Floquet analysis. The new time domain method can predict aeroelastic stability as well as time history.
Effect of Surface Roughness and Reynolds Number on Compressor Cascade Performance
Seung Chul Back(백승철),Seung Jin Song(송성진) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
An experimental work has been conducted in a linear compressor cascade to find out the effect of surface roughness and Reynolds number. Surveys were conducted with different roughness size and Reynolds number. The k<SUB>s</SUB>/c value of each roughness is 0.0006, 0.0090, 0.00150, 0.00213, and 0.00425. The range of Reynolds number is 300,000~600,000 and conducted with roughened blade, which roughness Ra is 2.89 microns. Flow pressure, velocity, and angle have been found out via 5 hole probe. Pressure loss and deviation increased with increasing roughness. In the low Reynolds number under 500,000, tested roughness does not affect to the performance of compressor cascade. However, roughness is very sensitive to pressure loss in high Reynolds number over 550,000.
제갈승(Seung Jegal),송성진(Seung Jin Song) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In a fuel cell vehicle using polymer electrolyte membrane fuel cell (PEMFC), hydrogen is over-supplied to gain higher stack efficiency. So it is needed considering fuel efficiency to re-circulate hydrogen which is not reacted in stack. And to re-circulate hydrogen, a blower or an ejector is used. Ejector re-circulation system has several merits compared with blower system, for example no parasite energy, simple structure and no lubrication system. But the secondary flow of an ejector in fuel cell vehicle, has high humidity because of crossover problem in stack. Therefore in this paper, ejector is designed by 1-D modeling and CFD with the primary and secondary flow of hydrogen. And the ejector which has the primary and secondary flow of air, is designed to have the same Reynolds number and Mach number at the nozzle exit as the hydrogen ejector’s. And this air ejector is tested while the humidity of the secondary flow is varied.
제갈승(Seung Jegal),송성진(Seung Jin Song) 한국유체기계학회 2008 유체기계 연구개발 발표회 논문집 Vol.2008 No.-
In a fuel cell vehicle using polymer electrolyte membrane fuel cell (PEMFC), hydrogen is over-supplied to gain higher stack efficiency. So it is needed considering fuel efficiency to re-circulate hydrogen which is not reacted in stack, And to re-circulate hydrogen, a blower or an ejector is used. Ejector re-circulation system has several merits compared with blower system, for example no parasite energy, simple structure and no lubrication system. But the secondary flow of an ejector in fuel cell vehicle, has high humidity because of crossover problem in stack. Therefore in this paper, ejector is designed by 1-D modeling and CFD with the primary and secondary flow of hydrogen. And the ejector which has the primary and secondary flow of air, is designed to have the same Reynolds number and Mach number at the nozzle exit as the hydrogen ejector's. Andthis air ejector is tested while the humidity of the secondary flow is varied.
제갈승(Seung Jegal),송성진(Seung Jin Song) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In a fuel cell vehicle using polymer electrolyte membrane fuel cell (PEMFC), hydrogen is over-supplied to gain higher stack efficiency. So it is needed considering fuel efficiency to re-circulate hydrogen which is not reacted in stack. And to re-circulate hydrogen, a blower or an ejector is used. Ejector re-circulation system has several merits compared with blower system, for example no parasite energy, simple structure and no lubrication system. But the secondary flow of an ejector in fuel cell vehicle, has high humidity because of crossover problem in stack. Therefore in this paper, ejector is designed by 1-D modeling and CFD with the primary and secondary flow of hydrogen. And the ejector which has the primary and secondary flow of air, is designed to have the same Reynolds number and Mach number at the nozzle exit as the hydrogen ejector's. And this air ejector is tested while the humidity of the secondary flow is varied.
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.