• Title/Summary/Keyword: Drag Divergence Mach Number

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Numerical Study on the Effect of Non-Equilibrium Condensation on Drag Divergence Mach Number in a Transonic Moist Air Flow (천음속 익형 유동에서 비평형 응축이 Drag Divergence Mach Number에 미치는 영향에 관한 수치 해석적 연구)

  • Choi, Seung Min;Kang, Hui Bo;Kwon, Young Doo;Kwon, Soon Bum
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.12
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    • pp.785-792
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    • 2016
  • In the present study, the effects of non-equilibrium condensation on the drag divergence Mach number with the angle of attack in a transonic 2D moist air flow of NACA0012 are investigated using the TVD finite difference scheme. For the same ${\alpha}$, the maximum upstream Mach number of the shock wave, Mmax, and the size of supersonic bubble decrease with the increase in ${\Phi}_0$. For the same $M_{\infty}$, ${\Phi}_0$, and $T_0$, the length of the non-equilibrium condensation zone ${\Delta}_z$ decreases with increasing ${\Phi}_0$. On the other hand, because of the attenuating effect of non-equilibrium condensation on wave drag, which is related to the interaction between the shock wave and the boundary layer, the drag coefficient $C_D$ decreases with an increase in ${\Phi}_0$ for the same $M_{\infty}$ and ${\alpha}$. For the same ${\alpha}$, $M_D$ increases with increasing ${\Phi}_0$, while $M_D$ decreases with an increase in ${\alpha}$.

Aerodynamic performance of Modified Sonic Arc Airfoil (수정 Sonic Arc 익형의 공력성능)

  • Lee, Jang-Chang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.7
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    • pp.581-585
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    • 2007
  • Sonic arc airfoil derived from the TSD theory is modified to new airfoil shape and its aerodynamic performance in transonic flow is investigated. The numerical simulation using Euler equations for the modified sonic arc airfoil is performed. The numerical results are compared with the aerodynamic performance of NACA0012 airfoil, of supercritical airfoil, and of NACA64A210 airfoil. In the same free stream Mach number of transonic flow, the pressure drag of the modified sonic arc airfoil is smaller than that of NACA0012 airfoil and the lift-drag ratio of the modified sonic arc airfoil is much larger than that of NACA0012 airfoil. In the comparison of the drag-divergence Mach number of transonic flow, the drag-divergence Mach number of the modified sonic arc airfoil is larger than that of NACA64A210 airfoil but is smaller than that of supercritical airfoil.

AERODYNAMIC ANALYSIS ON LEADING-EDGE SWEEPBACK ANGLES OF FLYING-WING CONFIGURATIONS (전익기 형상의 앞전후퇴각 변화에 따른 공력해석)

  • Lee, J.M.;Chang, J.W.
    • Journal of computational fluids engineering
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    • v.11 no.4 s.35
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    • pp.48-55
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    • 2006
  • A computational study was carried out in order to investigate aerodynamic characteristics on leading edge sweepback angles of Flying-Wing configurations. The viscous-compressible Navire-Stokes equation and Spalart-Allmaras turbulence model of the commercial CFD code were adopted for this computation analysis. This investigation examined aerodynamic characteristics of three different types of leading edge sweepback angles: $30^{\circ}C,\;35^{\circ}C\;and\;40^{\circ}C$. The freestream Mach number was M=0.80 and the angle of attack ranged from ${\alpha}=0^{\circ}C\;to\;{\alpha}=20^{\circ}C$. The results show that the increases in sweepback angle of the Flying-Wing configuration creates more efficient aerodynamic performance.

AERODYNAMIC DESIGN OPTIMIZATION OF ROTOR BLADE OA AIRFOILS (로터 블레이드 OA 익형의 공력 최적 설계)

  • Sa, J.H.;Park, S.H.;Kim, C.J.;Yun, C.Y.;Kim, S.H.;Kim, S.;Yu, Y.H.
    • Journal of computational fluids engineering
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    • v.14 no.2
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    • pp.25-31
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    • 2009
  • Numerical optimization of rotor blade airfoils is performed with a response surface method for helicopter rotor. For the baseline airfoils, OA 312, OA 309, and OA 407 airfoils are selected and optimized to improve aerodynamic performance. Aerodynamic coefficients required for the response surface method are obtained by using Navier-Stokes solver with k-$\omega$ Shear Stress Transport turbulence model. An optimized airfoil has increased drag divergence Mach number. The present design optimization method can generate an optimized airfoil with multiple design constraints, whenever it is designed from different baseline airfoils at the same design condition.

VALIDATION OF TRANSITION FLOW PREDICTION AND WIND TUNNEL RESULTS FOR KU109C ROTOR AIRFOIL (로터 익형 KU109C 풍동시험 및 천이유동 해석결과의 검증)

  • Jeon, S.E.;Sa, J.H.;Park, S.H.;Kim, C.J.;Kang, H.J.;Kim, S.B.;Kim, S.H.
    • Journal of computational fluids engineering
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    • v.17 no.1
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    • pp.54-60
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    • 2012
  • Transition prediction results are validated with experimental data obtained from a transonic wind tunnel for the KU109C airfoil. A Reynolds-Averaged Navier-Stokes code is simultaneously coupled with the transition transport model of Langtry and Menter and applied to the numerical prediction of aerodynamic performance of the KU109C airfoil. Drag coefficients from the experiment are better correlated to the numerical prediction results using a transition transport model rather than the fully turbulent simulation results. Maximum lift coefficient and drag divergence at the zero-lift condition with Mach number are investigated. Through the present validation procedure, the accuracy and usefulness of both the experiment and the numerical prediction are assessed.