• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.819-824
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• 2000

The flow inside an axial turbomachinery must be unsteady. Rotor-stator interaction by two blade rows influences performance, the generation of noise and vibration. So, it will be necessary to study the rotor-stator interaction for the design of an axial fan in which the axial gap between two blade rows is small. In this study, rotor-stator interaction is investigated by experimental methods. The research fan has one stage which consists of 24 rotor blades and 22 stator blades. Three-dimensional velocities measured using $45^{\circ}$ slanted hot wire probe and total pressure is measured using Kiel total pressure probe between rotor and stator with the axial 25%, 55%, 145% of chord length,. This study describes the influence of rotor-stator gap on the flow pattern, performance and loss. The efficiency curve show that the change of the rotor-stator gap make difference in the efficiency. And, the 3-dimensional velocity distribution show that the potential interaction between the rotor and the stator have a great effect on the flow field downstream of rotor, where there are wake flow. various vortices in hub region and leakage vortex in casing region etc.

• 대한기계학회논문집B
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• 제20권8호
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• pp.2561-2571
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• 1996

The flow in the turbomachinery is very unsteady due to the stator-rotor interaction. It has been indicated that the stator-rotor interaction has three distinct causes of unsteadiness: that is, the viscous vortex shedding, wake rotor interaction and potential stator-rotor interaction. In this paper, the mechanism of unsteady potential interaction and wake interaction in the stator-rotor stage flow is numerically investigated in two-dimensional view point. The numerical technique used is the upwind scheme of Van Leer's Flux Vector Splitting(FVS) and cubic spline interpolation is applied on zonal interface. Then, the flow field of a compressor stage composed of NACA 65410 is analyzed. Flow fields are found to be simulated reasonably by this method and the sensitivity due to back-pressure variation is more stronger than rotor-velocity variation.

• 한국유체기계학회 논문집
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• 제2권2호
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• pp.57-63
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• 1999

The flow through multistage turbomachinery is affected by the interaction between a rotor and a stator. The interaction is due to the inviscid potential effect and viscous effect between closely spaced rotor and stator airfoils. Three-dimensional, unsteady, incompressible Navier-Stokes equations with a standard $k-{\epsilon}$ model are solved using a non-staggered grid system. This method is applied to the flow through a multistage compressor measured by Stauter et al. The results have shown strong interaction between the rotating and stationary flow field. The decay of rotor wake and the pressure profiles agree very well with experimental data. The wake produced by rotor causes unsteady pressure on the surface of a stator. The rotor/stator interaction produces the unsteady pressure force on the rotor and stator blades.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.472-478
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• 2004

This paper describes the characteristics of the unsteady pressure on the stator surface induced by rotor viscous wakes. The primary object of this study is to investigate the effects of axial spacing between the rotor and the stator and three-dimensional vane geometries such as stator sweep and stator lean on the unsteady pressure fluctuations on the stator vane. To predict these fluctuations, unsteady three-dimensional Navier-Stokes analyses are performed. Furthermore, a three-dimensional analytical method using unsteady lifting-surface theory is also used to elucidate the mechanism of interaction of passing rotor wakes with downstream stator. Five different fan configurations with three sets of stator geometries, which are three radial stator configurations with different axial spacing, the swept stator and the swept and leaned stator, are used for this study. It is found that, in axial spacing between rotor and stator, the effect of radial phase skew of incoming rotor wake is important for the reduction of the induced unsteady pressure in addition to the rotor wake decay. It is also shown that incorporation of stator sweep and lean is effective to reduce this unsteady pressure.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.163-169
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• 1999

The numerical procedure has been developed for simulating incompressible viscous flow around a turbine stage with rotor-stator interaction. This study solves 2-D unsteady incompressible Navier-Stokes equations on a non-orthogonal curvilinear coordinate system. The Marker-and-Cell concept is applied to efficiently solve continuity equation. To impose an accurate boundary condition, O-H multiblocked grid system is generated. O-type grid and H-type grid is generated near and outer rotor-stator The cubic-spline interpolation is applied to handle a relative motion of a rotor to the stator. Turbulent flows have been modeled by the Baldwin- Lomax turbulent model. To validate present procedure, the time averaged pressure coefficients around the rotor and stator are compared with experiment and a good agreement obtained.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.153-156
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• 2006

A turbine stage consists of a stator and rotor. A stator provides the required inlet flow conditions so that a rotor can produce the necessary power. Passing wakes generated at the trailing edge of a stator make an interaction with a rotor. In the present study, this interaction flow mechanism is investigated using the numerical analysis. In case of the large gap distance between the stator and rotor, the stator and rotor flow analysis can be separated. First, only the stator flow field is solved. Second, the rotor flow field is solved including the passing wake information from the stator analysis. The passing wake experiences the shearing as it approaches to the rotor leading edge. And it is chopped when it strikes the rotor body. After that, the chopped wakes becomes the prolongation as it goes downstream. Also, the aerodynamic characteristics with the variation of the gap distance between a stator and rotor was investigated. Pressure jumps due to the passing wakes result in the pressure and lift loss and it gets stronger with the closer gap distance. This unsteady effect proves to be directly related to the fatigue and noise in turbomachinery and this study would be helpful to investigate such fields.

• 항공우주시스템공학회지
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• 제13권5호
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• pp.39-48
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• 2019

회전-고정자 혼합기 내의 난류 유동은 고속으로 회전하는 회전자와 고정자의 상호작용에 의해 발생되는 전단특성을 기반으로 한다. 본 연구에서는 유화연료 관련 회전-고정자 혼합기 시제품 모델에서 회전자와 고정자간의 상호작용에 의한 비정상상태 유동 특성 분석을 ANSYS FLUENT $k-{\varepsilon}$ (RKE) 난류 모델을 MRF 및 SMM에 적용하여 수행하였다. 회전자와 고정자의 경계에서 발생하는 유동 입자들의 거동과 전단 특성 그리고 설계 파라미터에 따른 속도분포와 난류와류소산 등의 경향을 전산유체역학 해석을 통해 예측 비교하여 모델의 효율성을 검증하였다.

• 대한기계학회논문집B
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• 제22권6호
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• pp.757-770
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• 1998

A Navier-Stokes code with a low Reynolds number k-.epsilon. turbulence model was tested to investigate its predictability for the unsteady transitional boundary layer flow due to rotor-stator interaction. A preliminary calculation with three different numbers of time steps 300, 600, and 1000 for a rotor wake passing period was carried out to see the effects of time steps on the unsteady flow and pressure fields due to rotor-stator interaction. Numerical solutions showed that unsteady pressure was much more sensitive to the number of time steps and over 600 time steps should be used to get a numerical solution independent of the number of time steps for a rotor wake passing period. The original low Reynolds number k-.epsilon. turbulence model showed very poor prediction of the unsteady transitional boundary layer flow due to rotor-stator interaction. This was due to the excessive production of turbulent kinetic energy near the leading edge. A modification suggested by Launder was incorporated and the modified model captured well the wake induced transitional strip. Present solutions also showed improved prediction over previous Euler/boundary layer solution in terms of the onset of unsteady transition and its extent.

• 대한기계학회논문집B
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• 제22권6호
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• pp.771-787
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• 1998

A Navier-Stokes code with a modified low Reynolds number k-.epsilon. turbulence model was used to study the unsteady transitional boundary layer flow due to rotor-stator interaction. The modification, proposed by Launder, to improve prediction of stagnation flows was incorporated to the low Reynolds number k-.epsilon. turbulence model by Fan-Lakshminarayana-Barnett. Numerical solution is shown to capture well the calmed laminar flow as well as the wake induced transitional strip due to rotor-stator interaction and shows improvement, in terms of onset of transition and its length, over previous Euler/boundary layer solution. The turbulent kinetic energy shows local maximum along the upstream rotor wake in the wake induced transitional strip and this characteristics is observed untill the end of transition. The wake induced strip also shown apparent even in the laminar sublayer as the upstream rotor wake penetrates inside the boundary layer.

• 한국전산유체공학회지
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• 제5권2호
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• pp.38-46
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• 2000

It has been indicated that the rotor/stator interaction has distinct causes of unsteadiness, such as the viscous vortex shedding, wake/stator interaction and potential rotor/stator interaction. In this paper, the mechanism of unsteady potential interaction in one stage axial compressor is numerically investigated for blade row ratio 1:1 and 2:3 at design point and for blade row ratio 2:3 at off-design point in two-dimensional view point. The numerical technique used is the upwind scheme of Van-Leer's Flux Vector Splitting(FVS) and Cubic spline interpolation is applied on zonal interface. In this study the flow unsteadiness due to potential interaction are found to be larger in blade row ratio 2:3 than in 1:1. The total pressure rise in blade row ratio 2:3 is closer to the real value in design point than that in 1:1. The change of unsteady pressure amplitude according to the variation of stator exit pressure is very small.