• Title/Summary/Keyword: Transonic flow

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Subsonic/Transonic Airfoil Design Using an Inverse Method (Inverse 기법을 이용한 아음속/천음속 익형 설계)

  • Lee Young-Ki;Lee Jae-Woo;Byun Yung-Hwan
    • Journal of computational fluids engineering
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    • v.3 no.1
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    • pp.46-53
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    • 1998
  • An inverse method for the subsonic and transonic airfoil design was developed using the Euler equations. Two testcases were performed. One was a verification of the method using the supercritical airfoil of the Korean mid-sized (100 passengers class) transport aircraft. The other was the design of an airfoil showing a good cruising performance (L/D ratio) in the high subsonic flow regime. These testcases demonstrated the efficiency and the robustness of the design method in the present study.

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Application of k-w turbulence model to the analysis of the flow through a single stage axial-flow compressor (단단 축류압축기 유동해석에 대한 k-w 난류모델의 응용)

  • Lee, Joon-Suk;Kim, Kwang-Yong
    • The KSFM Journal of Fluid Machinery
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    • v.3 no.3 s.8
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    • pp.7-11
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    • 2000
  • A numerical study based on the three-dimensional thin-layer Navier-Stokes solver is carried out to analyze the flowfield through a single stage transonic compressor. Explicit fout-step Runge-Kutta scheme with spatially variable time step and implicit residual smoothing is used. The governing equations we discretized with explcit finite difference method. Mired-out average method is used at the interface between rotor and stator. And, an artificial dissipation model is used to assure the stability of solution. The results with k-w turbulence model were compared to the results with Baldwin-Lomax model, and physical phenomena of transonic compressor are presented. The two turbulence models give the results that show reasonably good agreements with experimental data.

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A numerical Analysis on Three-Dimensional Inviscid Transonic Cascade Flow (3차원 비점성 천음속 익렬 유동에 관한 수치해석적 연구)

  • 이훈구;유정열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.2
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    • pp.336-347
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    • 1992
  • The three dimensional inviscid transonic cascade flow was investigated numerically, incorporation a four stage Runge-Kutta integration method proposed by Jameson. Time marching to the steady state was accelerated by using optimum time step and enthalpy damping. In describing the boundary conditions at inlet and outlet, Riemann invariants are considered. By adding a second and a fourth order artificial viscocities, the numerical instability due to the propagation of undamped disturbance or the rapid change of state near the shock has been prevented. The numerical results for are bump cascade, cambered two dimensional turbine cascade and three dimensional stator cascade agreed reasonably well with previous results. It has been known that the accuracy of the solution depended a lot on the modeling of the leading or trailing edge.

The Calculation of Three-Dimensional Viscous Flow in a Transonic, Multi-Stage Axial Compressor (다단축류압축기내의 천음속 점성유동에 대한 삼차원 수치해석)

  • Yi H. W.;Kim K. Y.
    • 한국전산유체공학회:학술대회논문집
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    • 1998.05a
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    • pp.181-189
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    • 1998
  • A numerical study based on the three-dimensional Reynolds averaged Navier-Stokes equations is presented to analyze the transonic flowfield through two-stage axial compressor. Explicit four-step Runge-Kutta scheme is used for solution algorithm, and local time step and implicit residual averaging are introduced for enhancing the convergency. Artificial dissipation model is adopted to assure the stability of solution. The solver is coupled with Baldwin-Lomax model to describe turbulence. To avoid calculating the unsteady flow, a mixing process is modeled at a station between rotating and stationary blade rows. Results show a variety of important physical phenomena. Comparison of the flowfields with and without tip clearance shows that the effect is considerable in this flowfield. Comparisons with experimental data carried out to validate the calculational results show reasonable agreements. Some remedies are also suggested to improve the revealed problems.

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Application of k-w turbulence model to the analysis of the flow through a single stage axial-flow compressor (단단 축류압축기 유동해석에 대한 k-w 난류모델의 응용)

  • Lee, Joon-Suk;Kim, Kwang-Yong
    • 유체기계공업학회:학술대회논문집
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    • 1999.12a
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    • pp.27-32
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    • 1999
  • A numerical study based on the three-dimensional thin-layer Navier-Stokes solver is carried out to analyze the flowfield through a single stage transonic compressor. Explicit four-step Runge-Kutta scheme with spatially variable time step and implicit residual smoothing is used. The governing equations are discretized with exploit finite difference method. Mixed-out average method is used at the interface between rotor and stator. And, an artificial dissipation model is used to assure the stability of solution. The results with k-$\omega$ turbulence model were compared to the results with Baldwin-Lomax model, and physical phenomena of transonic compressor are presented. The two turbulence models give the results that show reasonably good agreements with experimental data.

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PASSlVE SHOCK CONTROL IN TRANSONIC FLOW FIELD

  • Matsuo S;Tanaka M;Setoguchi T;Kashimura H;Yasunobu T;Kim H.D
    • Journal of computational fluids engineering
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    • v.10 no.1
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    • pp.80-86
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    • 2005
  • In order to control the transonic flow field with a shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock-boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

Passive Shock Control in Transonic Flow Field

  • Matsuo S.;Tanaka M.;Setoguchi T.;Kashimura H.;Yasunobu T.;Kim H. D.
    • 한국전산유체공학회:학술대회논문집
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    • 2003.10a
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    • pp.187-188
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    • 2003
  • In order to control the transonic flow field with shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock - boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

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Performance Analysis of Three-Dimensional Transonic Centrifugal Compressor Diffuser (3차원 천음속 원심압축기 디퓨져 성능연구)

  • Kim, Sang Dug;Song, Dong Joo
    • 유체기계공업학회:학술대회논문집
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    • 1998.12a
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    • pp.217-222
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    • 1998
  • CSCM upwind flux difference splitting compressible Navier-Stokes method has been used to predict the transonic flows in centrifugal compressor diffuser. The modified cyclic TDMA and the mass flux boundary conditions were used as boundary conditions of the diffuser analysis. With the mass flux boundary condition and the $130{\times}80{\times}40$ grid, the compressible upwind Navier-Stokes method predicted the transonic diffuser flowfield successfully. Plow changes in the impeller exit region due to the strong interaction between impeller exit and vaned diffuser, broad flow separation on the suction surface near hub and shroud was observed from the results of the mass flow rates 6.0 and 6.2kg/s at 27000 rpm. The static pressure increased and the total pressure decreased through the flow passage of the channel diffuser, which were predicted better from the three-dimensional analysis than from the two-dimensional analysis due to the strong effect of the three-dimensional flow. The mass averaged loss coefficients and pressure coefficients were also studied.

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Numerical Calculation of Three-Dimensional F1ow through A Transonic Compressor Rotor (천음속 압축기 동익을 지나는 삼차원 유동의 수치해석)

  • Lee, Yong-Gap;Kim, Gwang-Yong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.10
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    • pp.1384-1391
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    • 2001
  • Three-dimensional flow analysis is implemented to investigate the flow through transonic axial-flow compressor rotor(NASA R67) and to evaluate the performances of Abid's low-Reynolds-number k-$\omega$ and Baldwin-Lomax turbulence models. A finite volume method is used fur spatial discretization. The equations are solved implicitly in time by the use of approximate factorization. The upwind difference scheme is used for inviscid terms and viscous terms are approximated with central difference. The flux-difference-splitting method of Roe is used to obtain fluxes at the cell faces. Numerical analysis is performed near peak efficiency and near stall. The results are compared with the experimental data for NASA R67 rotor. Blade-to-Blade Mach number distributions are compared to confirm the accuracy of the code. From the results, it is concluded that Abid'k-$\omega$ model is better for the calculation of flow rate and efficiency than Baldwin-Lomax model. But, the predictions for Mach number and shock structure are almost the same.

Nonlinear Transonic Flutter Analysis of a Composite Fin Considering Delamination Effect (층간분리 효과를 고려한 복합재 핀의 비선형 천음속 플러터 해석)

  • Gwang Young Lee;Ki-Ha Kim;Dong-Hyun Kim
    • Journal of Aerospace System Engineering
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    • v.17 no.6
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    • pp.82-93
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    • 2023
  • In this paper, nonlinear transonic flutter analyses of a composite missile fin considering the effect of delamination are conducted. An effective modal analysis methodology is adopted and verified with the experimental modal test data for laminated composite plates with delamination. Extended version of the in-house computational aeroelastic analysis program with the transonic small-disturbance (TSD) code is used in order to predict the flutter dynamic pressure of the delaminated composite fin models. In the subsonic, transonic, and supersonic flow regions, nonlinear time-domain flutter analyses are performed for various delamination conditions, and aeroelastic characteristics due to the delamination phenomena are examined in detail.