CFD Sensitivity Analysis of a Modern Civil Transport Near Buffet-Onset Conditions

A computational fluid dynamics (CFD) sensitivity analysis is conducted for a modern civil transport at several conditions ranging from mostly attached flow to flow with substantial separation. Two different Navier-Stokes computer codes and four different turbulence models are utilized, and results are compared both to wind tunnel data at flight Reynolds number and flight data. In-depth CFD sensitivities to grid, code, spatial differencing method, aeroelastic shape, and turbulence model are described for conditions near buffet onset (a condition at which significant separation exists). In summary, given a grid of sufficient density for a given aeroelastic wing shape, the combined approximate error band in CFD at conditions near buffet onset due to code, spatial differencing method, and turbulence model is: 6% in lift, 7% in drag, and 16% in moment. The biggest two contributers to this uncertainty are turbulence model and code. Computed results agree well with wind tunnel surface pressure measurements both for an overspeed 'cruise' case as well as a case with small trailing edge separation. At and beyond buffet onset, computed results agree well over the inner half of the wing, but shock location is predicted too far aft at some of the outboard stations. Lift, drag, and moment curves are predicted in good agreement with experimental results from the wind tunnel.

[1]  Martin Berggren,et al.  A computational study of unsteady turbulent buffet aerodynamics , 2000 .

[2]  T. Gatski,et al.  On explicit algebraic stress models for complex turbulent flows , 1992, Journal of Fluid Mechanics.

[3]  R. Clark,et al.  High Reynolds number testing of advanced transport aircraft wings in the National Transonic Facility , 2001 .

[4]  Christopher L. Rumsey,et al.  Assessment of two-equation turbulence models for transonic flows , 1994 .

[5]  Stuart E. Rogers,et al.  Computation of Viscous Flow for a Boeing 777 Aircraft in Landing Configuration , 2000 .

[6]  H. Lomax,et al.  Thin-layer approximation and algebraic model for separated turbulent flows , 1978 .

[7]  P. Meredith,et al.  Areas for future CFD development as illustrated by transport aircraft applications , 1991 .

[8]  P. Spalart.  A One-Equation Turbulence Model for Aerodynamic Flows , 1992 .

[9]  D. Wilcox.  Turbulence modeling for CFD , 1993 .

[10]  T. Barth,et al.  A one-equation turbulence transport model for high Reynolds number wall-bounded flows , 1990 .

[11]  F. Menter.  Eddy Viscosity Transport Equations and Their Relation to the k-ε Model , 1997 .

[12]  R. A. Wahls.  The National Transonic Facility: A Research Retrospective , 2001 .

[13]  D. A. Johnson,et al.  Improvements to a nonequilibrium algebraic turbulence model , 1990 .

[14]  Feng Jiang.  CFD predictions for control surface effectiveness , 2000 .

[15]  V. Vatsa,et al.  Comparison of the predictive capabilities of several turbulence models , 1995 .

[16]  F. Menter.  Two-equation eddy-viscosity turbulence models for engineering applications , 1994 .

[17]  Christopher L. Rumsey,et al.  Prediction of Nonequilibrium Turbulent Flows with Explicit Algebraic Stress Models , 1995 .

[18]  L Krist Sherrie,et al.  CFL3D User''s Manual (Version 5.0) , 1998 .

[19]  L. Christopher,et al.  Efficiency and Accuracy of Time-Accurate Turbulent Navier-Stokes Computations , 1995 .

[20]  N E Suhs,et al.  PEGSUS 4.0 User's Manual , 1991 .

[21]  L Rumsey Christopher,et al.  Recent Turbulence Model Advances Applied to Multi-Element Airfoil Computations , 2000 .

[22]  F. Yuan,et al.  SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) , 1999 .

[23]  F. Menter.  Improved two-equation k-omega turbulence models for aerodynamic flows , 1992 .