Experimental vs. Computational Results

The rise in lift force is not very dramatic but does make a significant difference since it shows that a wing without a winglet would have to rise in angle of attack nearly a full degree to reach a similar lift as the winglet configuration. Although the CFD data match up directly to the wind tunnel data, this incremental difference between the two models is clear in both the CFD and wind tunnel data.

This figure shows an increase in drag in the winglet configuration according to the CFD which makes sense as there s been an addition of winglets which should change the area used to calculate drag. In the experimental model at lower angles of attack the drag is much higher. The experimental data actually shows a very similar drag at negative angles of attack which is not the case for the the simulated data. Since the test models also had a fuselage used for mounting purposes, some of the drag and lift discrepancies could be explained by this. The drag differences seen between the CFD data and experimental data are also due to issues in the simulated roughness of the models. Running simulations with different roughness has shown drastic changes in both lift and drag in both simulated configurations. It s likely that these results could be much closer if an average roughness was taken from the experimental test models and applied to the CFD simulation setup instead of the roughness currently being used.