Helicopter maneuvers on frigates develop an essential role during military operations. However, the complex flow generated by the frigate bluff-body shapes and the interaction with the helicopter downwash during the recovery process must be studied in detail. In addition, the ground effect can also affect helicopter performance during the maneuver. This study aims to use particle image velocimetry in wind tunnel to analyze the airflow generated by a 1:100-scaled helicopter rotor of the Sea King SH-3 navy helicopter isolated and with the presence of a full and a partial ground to consider the ground effect at different heights. Once the rotor has been studied, experimental tests were carried out of the rotor working next to a frigate model during the recovery maneuver. The measured velocity indicates that the flow asymmetry below the rotor can increase with the proximity to a partial ground distance up to 1.39 times. During the study of the rotor for the frigate landing approach, the downwash asymmetry is also important and changes abruptly the tendency during the last phase of the maneuver. It can lead to dangerous instabilities and problems for the helicopter pilot during the hovering over ships.

护卫舰上的直升机演习在军事行动中发挥着重要作用。然而，必须详细研究由护卫舰钝体形状产生的复杂流动以及在恢复过程中与直升机下洗流的相互作用。此外，地面效应也会影响直升机在机动过程中的性能。本研究旨在利用风洞中的粒子图像测速技术，分析海王SH-3海军直升机的1:100比例直升机旋翼产生的气流隔离，并在存在全地面和部分地面的情况下考虑地面不同高度的效果。一旦研究了旋翼，在恢复机动期间对在护卫舰模型旁边工作的旋翼进行了实验测试。测得的速度表明转子下方的流动不对称性会随着接近部分地面距离而增加，最高可达 1.39 倍。在护卫舰登陆进近旋翼的研究中，下洗不对称也很重要，并且在机动的最后阶段突然改变趋势。它会导致直升机飞行员在船舶上空盘旋时出现危险的不稳定和问题。