DPW-5 Analysis of the CRM in a Wing-Body Configuration Using Structured and Unstructured Meshes

Abstract

Two general purpose Reynolds Averaged Navier-Stokes (RANS) flow solvers, OVERFLOW and BCFD, are used to analyze the NASA Common Research Model (CRM) in a wing-body configuration. The codes are run on structured and unstructured common grid families built specifically for the 5 th AIAA CFD Drag Prediction Workshop (DPW-5) allowing for meaningful comparison of data. There are six grid sizes in the family ranging from a 0.6 million cell "Tiny" mesh up to a 138 million cell "Super-Fine" mesh. Results from a grid convergence study are evaluated for each solver and grid type with focus on isolating individual effects of turbulence model and differencing scheme on computed forces, moments and wing pressures. A "Medium" mesh consisting of 5.1 million cells is used to run the wing-body configuration through an angle-of-attack sweep as part of a buffet onset study. The solutions are used to better understand variations in high speed wing separation prediction driven by the strengthening shock and by corner flow physics at the wing-body juncture. Numerical simulation of side-of-body separation continues to be a challenge for RANS methods where solutions are sensitive to grid density and turbulence model, amongst other variables. However, a newly developed quadratic constitutive relation (QCR) is employed with favorable results. Two additional studies are conducted to: a) investigate how well common grid solutions compare with those on a grid built using best practices for a given flow solver, and b) quantify the effects of transition and wing twist to provide additional corrections needed for comparisons of CFD results with experimental data. Nomenclature AR = wing aspect ratio, b 2 /S r e f count = drag coefficient unit, 0.0001 b = wing span DPW = drag prediction workshop CFD = computational fluid dynamics N = number of grid points C D = drag coefficient, Drag/(q  S ref ) RANS = Reynolds-averaged Navier-Stokes C L = lift coefficient, Lift/(q  S ref ) S ref = wing reference area C M = pitching moment coefficient, Moment/(q  S ref c ref ) X = x-coordinate location, streamwise C P = pressure coefficient, (P-P  )/q  Y = y-coordinate location, spanwise c ref = wing reference chord  = angle-of-attack c = chord  = wing semi-span location, Y/(b/2)

Validation of Wing Deformation Simulations for the NASA CRM Model using Fluid-Structure Interaction Computations

“…9 For improved prediction of turbulent normal stress anisotropy near viscous walls, which is considered responsible for secondary corner flow phenomena, the Quadratic Constitution Relation (QCR) extension 10 is applied. Yamamoto et al 11,12 and Sclafani et al 13 have shown that the flow separation in the wing-fuselage intersection of NASA's CRM configuration, which is predicted by CFD but was not observed in the experiments, will be suppressed by QCR.…”

Large-Scale Swept-Wing Icing Simulations in the NASA Glenn Icing Research Tunnel Using LEWICE3D

“…The CRM is a large, swept-wing transport similar to existing commercial wide-body aircraft. A body of literature for the CRM is available in the public domain including the model geometry, 2 computational results, 3,4,5,6,7 and experimental data. 8,9 Figure 1 shows the full configuration of the CRM including the wing, body, horizontal tail, and nacelle-pylon group.…”

On the numerical solution of compressible fluid flow and radiative heat transfer problems

“…Computational system DELL T7500 workstation with two Intel (R) Xeon (R) -X5650 six-core processors at 2.67 GHz In Figure 7.87 the refined coarse mesh density and predicted dimensionless pressure contours on the aircraft surface are illustrated, demonstrating their qualitative agreement with those of other solvers [Lee10,Mav10]; similarly to the WB aircraft and independently of the mesh density no significant wingbody juncture separation was observed, while the same stands for horizontal tail-body juncture separation (probably due to the SST turbulence model utilized [Scl13]). Figures 7.88-7.101 contain the pressure coefficient distributions at different wing and horizontal tail span-wise sections for the initial coarse, the refined coarse, the initial medium and the refined medium mesh, compared to those of the study of Lee-Rausch et al [Lee10]; in Figures 7.88-7.90 and 7.95-7.101 the distributions, derived by the initial grids (coarse and medium) are not contained, as they are the same to those of the corresponding refined ones.…”

“…Computational system DELL T7500 workstation with two Intel (R) Xeon (R) -X5660 six-core processors at 2.80 GHz No considerable wing-body juncture separation at the upper side of the wing was observed, similarly to some of the participants of the DPW's [Cez13,Par13,Sca13,Scl13]; its absence might derive from the utilization of a relatively coarse mesh along with the SST turbulence model [Scl13]. Figures 7.70 up to 7.75 contain the pressure coefficient distributions at different wing span-wise sections of the aircraft, compared to the corresponding experimental and reference calculated ones [Sca13].…”

“…The last fluid flow test case encountered in this study, concerns the fully turbulent flow over the NASA CRM aircraft with (Wing-Body-Horizontal Tail, WBHT) and without horizontal tail (Wing-Body, WB) [Lee10, Mav10, Cez13, Mur13, Par13, Sca13, Scl13, Vos10, Vos13, Lyg14a, Lyg15, Sar15]; the aforementioned problem was examined by the participants of the fourth and fifth AIAA Drag Prediction Workshop (DPW), held in San Antonio in 2009 and in New Orleans in 2012, respectively. The CRM, which is a 2.7% scaled representative of a modern commercial transonic flow aircraft, was designed specifically for the evaluation of CFD codes [Scl13]. Therefore, the geometry parameters as well as the experimental (wind tunnel) results are available; furthermore, most of the grids used by the participants of the pre-mentioned DPW's can be obtained from the NASA Langley Research Center (LARC) (http://aaac.larc.nasa.gov/tsab/cfdlarc/aiaadpw).…”