UHCA Wing-Body Configuration

Figure 4: UHCA: Surface pressure distribution and streamlines

Turning the attention to three-dimensional testcases, an Ultra-High Capacity Aircraft (UHCA) wing-body configuration, Fig. 4, is computed at $Ma=0.85$, $Re=2.8 \cdot 10^{6}$ and $\alpha=2.66^{\circ}$. This case is of particular interest since it represents a combination of high Mach numbers and a comparatively high angle-of-attack for transonic flows, yielding a shock-induced separation over large portions of the wing, see Fig. 5. A grid generated by Airbus Germany of 52 equal-sized blocks with $25\cdot41\cdot45$ mesh nodes and 38,642 surface points, totalling to approximately 2.4 million points, is employed. A $y^{+}\approx1$ is guaranteed over most of the wing surface. The transition location is prescribed according to given data. The computations are performed with FLOWer, LLR and LEA $k$-$\omega$ are compared to the baseline Wilcox model. The pressure distribution in selected wing sections are given in Fig. 6. While the pressure side including the rear loading is captured very well by all models, a clear improvement in the prediction of the shock location on the suction side from Wilcox over LEA to LLR $k$-$\omega$ is visible in the mid-span section. However, in the most outboard section, the shock appears to be somewhat smeared out, probably owing to an insufficient grid resolution in this region. Thus, it is not possible to make a clear judgement whether LLR or LEA $k$-$\omega$ yields a superior prediction here. Nonetheless, the enhanced predictive accuracy with respect to the Wilcox model is evident.

Figure 5: UHCA: Surface pressure distribution and streamlines on wing upper surface, LLR $k$-$\omega$

Figure 6: UHCA: Pressure distribution in selected wing sections