The ditching performance of a BWB aircraft is studied using the numerical method. The unsteady Reynolds-Averaged Navier-Stokes equations and the Realizable $k-\epsilon$ turbulence model are solved by the finite volume method, the implicit volume-of-fluid model is adopted to capture the water-air interface, the six-degree-of-freedom model is employed to couple fluid dynamics and aircraft rigid-body kinematics, and the global moving mesh is used to deal with the relative motion between the aircraft and the water. The accuracy of the present numerical method is validated by the high-speed ditching experiment of a 3D flat plate. The porpoising motion of the BWB aircraft during ditching is discovered for the first time, and this motion is independent of the initial pitch angle, i.e., the amplitude and period of the motion and load curves are coincident for different initial angles. The porpoising motion is determined by a couple of hydrodynamic and aerodynamic loads, and the total load peak is mainly caused by the former. The hydrodynamic load is mainly from the staggered positive-negative pressure stripe on the aircraft belly. The variation in aerodynamic load is mainly induced by the compression work in the dynamic ground effect.

采用数值方法研究了BWB飞机的迫降性能。非定常 Reynolds-Averaged Navier-Stokes 方程和 Realizable$克-\epsilon$湍流模型采用有限体积法求解，采用隐式流体体积模型捕捉水-空气界面，采用六自由度模型耦合流体动力学和飞机刚体运动学，全局移动网格用于处理飞机与水的相对运动。通过3D平板高速开沟实验验证了该数值方法的准确性。首次发现了BWB飞机在俯仰时的海豚式运动，该运动与初始俯仰角无关，即不同初始角度下运动和载荷曲线的幅度和周期是一致的。海豚运动由一对流体动力和空气动力载荷决定，总负荷峰值主要由前者引起。水动力载荷主要来自机腹上交错的正负压条纹。气动载荷的变化主要是由动力地效中的压缩功引起的。