Vortical Flow Prediction of the AVT-183 Diamond Wing

Abstract

The objective of this paper is to assess the potential and limitations of current practice in computational fluid dynamic modeling for predicting vortical flowfields over a generic 53-degree swept diamond wing with rounded leading edges. This wing was designed under STO AVT Task Group 183 and is based on the SACCON UCAV geometry, which is a lambda wing with complex span-wise distributions of thickness and leading edge radius and with a linear twist outboard of the first trailing edge break. The SACCON wing trailing-edge was swept forward by 26.5-degrees to form a diamond-shaped planform that is used in this study. This new wing also has a constant NACA 64A-006 airfoil section with a leading edge radius of 0.264 percent chord and has no twist. CFD simulations were performed for various angles of attack at a Mach number of 0.15 and a Reynolds number of 2.7× 10 6 based on the mean aerodynamic chord to match experiments. CFD simulations were run with different turbulence models and with a limited assessment of Delayed Detached Eddy Simulation. The wind tunnel experiments of the diamond wing were carried out in the and include aerodynamic lift, drag, and pitch moment measurements as well as span-wise pressure distributions at different chord-wise locations. This data set is used to validate the CFD results. The results presented demonstrate that the CFD compare well with the experiments at small angles of attack; the pitch moment predicted by the SARC turbulence model provide a better match to experimental results than the SA model at moderate angles of attack; and at high angles of attack, CFD predictions are not as good. The flow visualization results show that a leading-edge vortex is formed above the upper surface of the wing at an angle of attack of about eight degrees. This vortex becomes larger and stronger when the angle of attack is increased. With increasing angle of attack, the vortex formation point moves upstream and the vortex core moves inboard towards the wing center. Finally, the results show that the flow over the diamond wing is steady throughout the range of angles of attack.

Leading-Edge Roughness Effects on the Flow Separation Onset of the AVT-183 Diamond Wing Configuration (Invited)

“…These data sets are used for the relevant CFD comparisons. [15][16][17][18][19][20][21][22] In this section, the short term repeatability of the single W/T runs is considered. Overall, the short term repeatability of the W/T measurements is found to be very good, both for the aerodynamic forces and moments as well as for the steady surface pressures.…”

“…In the present paper, the force and the steady surface pressure measurements from the first W/T campaign are regarded, while the Stereo PIV, the hot-wire and the unsteady surface pressure measurements undertaken within the other W/T campaigns are regarded in a related paper by Hövelmann et al 14 In the context of the present task group AVT-183, the obtained W/T results are also considered as comparison data for the numerous numerical computations that are available. [15][16][17][18][19][20][21][22] Beyond that, the conducted W/T investigations provide in general an extensive experimental data base for overall CFD validation, which focus on smooth surface separation with consecutive leading-edge vortex formation at a moderately swept, low aspect ratio wing with rounded leading-edge contour.…”

Technology challenges of stealth unmanned combat aerial vehicles

“…Applied Vehicle Technology group (AVT) under the AVT-080, 113, 161, 183 and 201 research groups (70)(71)(72)(73) .…”

Evaluation of Reduced-Order Models for Predictions of Separated and Vortical Flows

“…The 2D NACA0012 unstructured grid is shown in Figure 1(a) and the 3D NACA64A006 unstructured grid is shown in Figure 1(b). The geometry for the NACA64A006 case includes a peniche, mimicking the experimental configuration studied by Hövelmann et al 23 A total of 70198 grid cells 24 are used for each of the NACA0012 simulations and 13.2 million grid cells 25 are used for each of the NACA64A006 simulations. The Spalart-Allmaras rotation corrected (SARC) RANS model is used for both cases with second-order spatial accuracy.…”