Using the commercially available FLUENT 3-D flow field solver, this research effort investigated vortex breakdown over a delta wing at high angle of attack (a) in preparation for investigation of active control of vortex breakdown using steady, along- core blowing A flat delta-shaped half-wing with sharp leading edge and sweep angle of 600 was modeled at a 180 in a wind tunnel at Mach 0,04 and Reynolds number of 3,4 x 10(sub 5). A hybrid (combination of structured and unstructured) numerical mesh was generated to accommodate blowing ports on the wing surface. Results for cases without and with along-core blowing included comparison of various turbulence models for predicting both flow field physics and quantitative flow characteristics, FLUENT turbulence models included Spalart-Allmaras (S-A), Renormalization Group k-e, Reynolds Stress (RSM), and Large Eddy Simulation (LES), as well as comparison with laminar and inviscid models. Mesh independence was also investigated, and solutions were compared with experimentally determined results and theoretical prediction, These research results show that, excepting the LES model for which the computational mesh was insufficiently refined and which was not extensively investigated, none of the turbulence models above, as implemented with the given numerical grid, generated a solution which was suitably comparable to the experimental data. Much more work is required to find a suitable combination of numerical grid and turbulence model.

This paper presents the results of research conducted by Alenia (Italy), Dasa (Germany), DERA (United Kingdom), NLR (The Netherlands), and DLR (Goettingen, Germany) as part of the Western European Armaments Group (WEAG) TA15 program, Common Exercise V. The WEAG TA15 program was a collaborative program concerned with the investigation of steady and unsteady vortical flows over military aircraft configurations. An important component of the program were the Common Exercises (CE), which promoted the exchange of knowledge between the participating nations and aided the development of computational methods to predict vortical flows. As the analysis of flow fields about rolling delta wings is of high interest, the last CE of this group concentrated on the numerical and experimental investigation of unsteady flow over a 65 degree swept delta wing in rolling motion at transonic speed. Guided by previous work on unsteady motions, the numerical investigation was again restricted to unsteady Euler methods. Each participant for the numerical calculations was asked to perform unsteady Euler calculations for given test cases using a mandatory grid and a given number of physical time steps per period. Numerical calculations with different unsteady Euler methods using a common grid were performed at a constant rolling rate of omega(r)=0.0762 for different angles of incidence: alpha(sub 0)=0 degrees, alpha(sub 0)=10 degrees, and alpha(sub 0)=17 degrees. The numerical results reveal that the different spatial discretizations lead to characteristic differences mainly in the magnitudes of the vortex-induced suction peaks in the unsteady pressure distributions and in the prediction of vortex breakdown. The results should finally result in the development of a data base for further code validation. (13 figures, 14 refs.).