• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.91-98
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• 2001

As the second part of the author's study, off-design behavior of the design and performance parameters in the low-solidity cascade diffuser in a centrifugal compressor is investigated. The experimental flange-to-flange compressor map serves the validity of application of the present CFD work to the detailed investigation of the low-solidity cascade diffuser. Some meanline design and performance parameters as well as three-dimensional internal secondary flow fields are studied when the flow rate is changed from deep choke to stall.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3639-3648
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• 1996

The effect of 15% pinched diffuser in a centrifugal air compressor with a cascade airfoil diffuser on the aerodynamic performance is investigated using a numerical approach. The commercial CFD code for three-dimensional, turbulent, compressible flow fields is executed for various mass flow rates at a design speed which can be obtained as long as the calculation succeeds. The pinched diffuser is found to help improve the instability of flow within vaneless diffuser space, especially the reverse flow near shroud, and to change both stall/surge line and choking line to increase the surge margin. It is also found to generate more favorable increase of static pressure in diffuser region, and to increase the resulting pressure ratio and efficiency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.35-35
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• 1998

충격파의 경사반사는 초음속 비행체의 외부유동, 대형압축기의 디퓨져 내의 유동, 증기 터어빈 최종단 익렬유동, 데토네이션파가 벽면에 입사하는 유동 혹은 램제트의 연소공기 유입구 유동 등 초음속 유동에서 흔히 발생하며 이때의 유동장의 해석과 충격파 감쇄, 충격파와 간섭하는 벽면의 영향 등은 공학적으로 구명되어져야 할 중요한 문제이다. 전파하는 평면충격파가 벽면에 입사하는 경우 일어나는 충격파 경사반사는 크게 정상반사와 마하반사로 대별된다. 정상반사와 마하반사 간의 천이기준에 대한 연구는 오래 전부터 수행되어 왔고 입사충격파가 약한 경우 이론적 천이 기준인 이탈기준(detachment criterion)과 실험값의 차이 즉 Neumann paradox가 존재한다는 것이 밝혀졌다.