Abstract Insight into the effects of motions and waves on a ship airwake can be used to provide information regarding safe conditions for at sea flight operations and pilot training. We present a study on the effects of waves and motions on a ship's airwake and a helicopter operating above the flight deck using full scale computational fluid dynamics simulations. The ONR Tumblehome Ship (ONRT) geometry is analyzed in wind and regular head waves corresponding to nominal sea states 3 and 6. In order to separate the effects of waves and motions, simulations are conducted for both sea states with combinations of: waves and motions, waves and no motions, no waves with motions, and no motions or waves. A triple velocity decomposition is conducted in order to quantify changes in the airwake due to motions and waves. The aerodynamic loads on a helicopter hovering in the airwake are studied with one-way and two-way coupling approaches. The one-way coupled analysis uses the velocity field data from the full scale airwake simulations along with disk actuator theory to calculate thrust fluctuations for three different rotor sizes operating above the flight deck. In the two-way coupled study a helicopter loosely based on the Sikorsky SH-60 Seahawk hovering above the flight deck of the ONRT is simulated, including dynamic overset grids of the main rotor, tail rotor and fuselage. This approach captures the interaction between the rotor downwash and the ONRT airwake. The study shows that for the lower sea state 3 the motions and waves have little effect on the airwake behavior, exhibiting little change with respect to the baseline case without motions and waves. At sea state 6 the flow field is modified significantly, which also affects the forces on the helicopter. Force fluctuations show main peaks at the wave encounter frequency and the blade passage frequency, as well as higher harmonics. The one-way coupling approach shows that larger rotors effectively filter out small scale fluctuations while smaller diameter rotors are affected by smaller flow structures.

中文翻译：

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波浪和运动中的船舶气流以及对直升机操作的影响

摘要 对运动和波浪对船舶气流影响的洞察可用于提供有关海上飞行操作和飞行员培训的安全条件的信息。我们使用全尺寸计算流体动力学模拟来研究波浪和运动对船舶尾流和在飞行甲板上方运行的直升机的影响。ONR Tumblehome Ship (ONRT) 几何在与标称海况 3 和 6 对应的风和常规顶浪中进行分析。为了分离波浪和运动的影响，对两种海况进行了模拟，并结合了：波浪和运动，波浪和无运动，没有运动的波浪，没有运动或波浪。进行三重速度分解以量化由于运动和波浪引起的气流变化。用单向和双向耦合方法研究了在尾翼中盘旋的直升机的气动载荷。单向耦合分析使用来自全尺寸尾流模拟的速度场数据以及盘式致动器理论来计算在飞行甲板上方运行的三种不同转子尺寸的推力波动。在双向耦合研究中，模拟了基于西科斯基 SH-60 海鹰在 ONRT 飞行甲板上方盘旋的直升机，包括主旋翼、尾旋翼和机身的动态重叠网格。这种方法捕获转子下洗流和 ONRT 气流之间的相互作用。研究表明，对于较低的海况 3，运动和波浪对空气尾流行为的影响很小，相对于没有运动和波浪的基线情况几乎没有变化。在海况 6 时，流场发生了显着变化，这也会影响直升机上的力。力波动在波浪遭遇频率和叶片通过频率以及高次谐波处显示出主要峰值。单向耦合方法表明，较大的转子可有效滤除小尺度波动，而较小直径的转子则受较小流动结构的影响。