Summary Data from the Sixth AIAA CFD Drag Prediction Workshop: CRM Cases

Abstract

Results from the Sixth AIAA CFD Drag Prediction Workshop Cases 2 to 5 are presented. These cases focused on force/moment and pressure predictions for the NASA Common Research Model wing-body and wing-body-nacellepylon configurations. The Common Research Model geometry differed from previous workshops in that it was deformed to the appropriate static aeroelastic twist and deflection at each specified angle of attack. The grid refinement study and nacelle-pylon drag increment prediction (Case 2) used a common set of overset and unstructured grids, as well as user-created multiblock structured, unstructured, and Cartesian-based grids. Solutions were requested for both the wing-body and wing-body-nacelle-pylon at a fixed Mach number and lift coefficient. The wing-body static aeroelastic/buffet study (Case 3) specified an angle-of-attack sweep at finely spaced intervals through the zone where wing separation was expected to begin. The optional Case 4 requested grid adaption solutions of the wing-body at a specified flight condition. Optional Case 5 requested coupled aerostructural wing-body solutions. Results from this workshop highlight the progress made since the last workshop, and the continuing need for computational fluid dynamics (CFD) improvement, particularly for conditions with significant flow separation. These comparisons also suggest the need for improved experimental diagnostics to guide future CFD development.

Global instability of wing shock-buffet onset

“…Figures 2 through 5 show a steady validation of the simulations reported herein. Aerodynamic coefficients of lift, drag and pitching moment, given in figure 2, at seven angles of attack between α = 2.5 • and 4.0 • in increments of 0.25 • suggest a fairly good agreement between the steady RANS simulations and wind tunnel data (from continuous-pitch run 153), when compared to the spread in various other numerical predictions (see for example Tinoco et al 2018). The clear offset in moment coefficient, reported elsewhere, too, is not fully understood but could result from the partial correction applied to account for the model mounting system.…”

“…to achieve a smaller increment when tracing the global modes herein, interpolation was used (Keye & Gammon 2018). The computational mesh was deformed accordingly (and then kept frozen for subsequent steady and unsteady flow computations making it quasi-rigid), a functionality readily available in the chosen flow solver, to improve numerical predictions (Tinoco et al 2018). Wind tunnel force measurements have been corrected for wall interference and include a correction due to buoyancy effects of the mounting system (Rivers, Quest & Rudnik 2018).…”

Quantification of model uncertainty in RANS simulations: A review

“…The location of the presented pressure distribution is indicated by the red/solid line on the wing (see inset; showing the port half of the fuselage and the wing only).Figure reprintedwith permission from Tinoco et al[24]. Panel (b) shows the C p profile on a NACA0012 airfoil in a transonic flow with freestream Mach number 0.8 and Reynolds number 9 × 10 6 , obtained from RANS simulations with the algebraic model of Baldwin and Lomax…”

The Objective Space and the Formulation of Design Requirement in Natural Laminar Flow Optimization

“…The AIAA Aerodynamic Design Optimization Discussion Group (ADODG) has defined benchmark optimization problem of airfoil RAE2822 in viscous (Reynolds number is 6.5 million), transonic flow (freestream Mach number is 0.734), subject to lift (0.824), pitching moment (not smaller than −0.092), and area (decrement is not allowed) constraints [36]. The problem has been studied by many scholars, which has significance with respect to engineering applications [37][38][39][40].…”