Ditching Performance Comparison of Blended-Wing-Body and Tube-and-Wing Aircraft

The ditching processes of the BWB-450 and B747 with various initial pitch angles are simulated by numerically solving the unsteady Reynolds-averaged Navier–Stokes equations to evaluate the influence of layout. The volume of fluid algorithm is used to capture the water/air interface, while the three-degree-of-freedom model couples the motion and load of the aircraft. The accuracy of the numerical method in simulating motion and load is validated by comparison with the experimental results obtained from the dynamically scaled BWB-450 model. Analysis of motion and load characteristics reveals that the optimal initial pitch angles for both the BWB-450 and B747 are 12 deg. A subsequent comparison of the ditching processes under these optimal angles shows that the motion amplitude and peak load of the BWB-450 are significantly greater than those of the B747. Moreover, the maximum vertical acceleration at the front of the BWB-450 exceeds the human tolerance limit, although the duration of the acceleration pulse remains within allowable limits. Because the BWB-450 periodically jumps off the water surface while the B747 remains submerged, and considering the much higher damping effect of water compared to air, the mechanical energy attenuation of the BWB-450 is significantly slower than that of the B747.