舰船运动对机舰耦合流场的影响研究

Research on the Influence of Ship Motion on Ship/Helicopter Coupled Flow Field

摘要: 机舰耦合流场是一个复杂紊乱的非定常流场，存在着涡–涡干扰现象。在真实海况下，舰船的六自由度摇摆运动会进一步恶化飞行甲板上方的流场环境，因此有必要探究舰船的摇摆运动对飞行甲板上方机舰耦合流场的影响。现基于简化护卫舰和双桨旋翼的耦合模型，通过CFD方法对舰船纵摇状态下的机舰耦合流场进行了数值模拟研究，定性分析了耦合流场结构的发展变化，同时对旋翼拉力进行了定量分析。随着舰船的纵摇运动，摆动的机库尾涡会和桨尖涡混合在一起，垂向气流也在不断变化，旋翼拉力、压强和速度都出现了近似周期性的变化，和纵摇运动的周期一致。相比于舰船的静止状态，当甲板上扬至水平位置附近时，旋翼拉力最大，增加约14%，当甲板下沉至水平位置附近时，旋翼拉力最小，减少约12%，因此直升机要具有足够的操纵量，及时改变总距以保证直升机在该状况下的安全性。

Abstract: The ship/helicopter coupled flow field is a complex and chaotic unsteady flow field, where exist vortex-vortex interference phenomenon. Under real sea conditions, the six-degree-of-freedom swing motion of the ship will further worsen the flow field environment above the flight deck, so it is necessary to explore the influence of the ship’s motion on the coupled flow field above the flight deck. Based on the simplified coupling model of frigate and rotor, the coupled flow field between the ship and the aircraft in the pitching state is numerically simulated by CFD method, and the development and change of the coupled flow field structure are qualitatively analyzed, and the rotor thrust is quantitatively analyzed. With the ship’s pitching motion, the hangar wake vortex will be mixed with the blade tip vortex, and the vertical airflow will also change constantly. The rotor thrust, pressure and velocity all change approximately periodically, which is consistent with the period of pitching motion. Compared with the static state of the ship, when the deck rises to the horizontal position, the rotor thrust is the largest, increasing by about 14%, and when the deck sinks to the horizontal position, the rotor thrust is the smallest, decreasing by about 12%. Therefore, the helicopter should ensure that the helicopter has enough operating margin, and timely adjust the collective pitch to enhance the helicopter's take-off and landing safety in this situation.