The present study numerically explored the hydrodynamic characteristics of a helicopter model experiencing guided ditching on wavy water. The air–water two-phase flow was computed by solving unsteady incompressible Reynolds-averaged Navier–Stokes equations enclosed by the $k\text{-}\omega$ shear stress transport turbulence model. The effect of water-entry position of the wave, viz., crest, falling, rising and trough, on the ditching behavior of a helicopter was assessed under different initial pitching angles. Results show that the hydrodynamic characteristics of the helicopter ditching on wavy water is significantly different from ditching on still water. Ditching on the crest of a wave illustrates the best performance in terms of angular, vertical, and horizontal acceleration that results from a skiing motion to minimize the hydrodynamic overload. On the other hand, ditching on trough will result in the most severe overload because the largest impacting area of the helicopter provides a relatively large reactive force to decelerate the descending motion of the helicopter. Within the tested angles, ditching on crest is always the best option. The initial pitching angle is influential to the rising and trough cases, such that a smaller pitching angle is suggested for ditching a rising wave, and alternatively, a larger angle is suitable for trough.

本研究从数值上探讨了在波浪水上进行引导式开沟的直升机模型的水动力特性。通过求解非定常不可压缩的雷诺平均Navier-Stokes方程，可以计算出空气-水两相流。$ķ\text{--}\omega$剪应力传输湍流模型。在不同的初始俯仰角下，评估了波浪的进水位置，即波峰，下降，上升和低谷对直升机的俯仰行为的影响。结果表明，在波浪水上进行直升机开沟的水动力特性与在静止水上进行沟渠的水动力特性显着不同。在波峰上开沟说明了最佳的性能，该性能是由滑雪运动产生的将水动力过载最小化的角加速度，垂直加速度和水平加速度的最佳表现。另一方面，在槽上开沟会导致最严重的过载，因为直升机的最大撞击区域会提供相对较大的反作用力，以使直升机的下降运动减速。在测试角度范围内，顶上沟渠始终是最好的选择。初始俯仰角对上升和下降情况有影响，因此建议使用较小的俯仰角来分离上升波，或者，较大的角度适合于下降。