In this study, a moderately flexible rotor is investigated experimentally in a water channel. The rotor consists of a single blade with a simplified rectangular geometry and is tested with various pitch angles at different rotational speeds. The flapwise bending deformation and induced torsion of the blade are measured using image processing tools, and flow fields are extracted with Particle Image Velocimetry. The blade deformation behaviour depends strongly on the pitch angle, it includes extreme downstream and upstream bending for high negative and positive pitch, respectively. In addition, large-amplitude, low-frequency bending fluctuations are observed in a certain range of rotational speeds for negative pitch. The wake vorticity fields show large-scale recirculation zones being formed and intermittently shed behind the rotor, resembling the dynamics of the Vortex Ring State known from helicopter aerodynamics. A comparison with the flow generated by a rigid rotor of the same geometry is also carried out.

在这项研究中，在水道中对挠性适中的转子进行了实验研究。转子由具有简化矩形几何形状的单个叶片组成，并以不同的螺距角在不同的转速下进行了测试。使用图像处理工具测量叶片的翼向弯曲变形和引起的扭转，并使用粒子图像测速仪提取流场。叶片变形行为在很大程度上取决于桨距角，它分别包括极端的下游弯曲和上游弯曲，分别用于高负向和正向俯仰。另外，在一定的转速范围内，对于负间距观察到大振幅，低频弯曲波动。尾流涡流场显示出形成了大规模的回流区，并在转子后断断续续地散布着这些回流区，类似于直升机空气动力学中已知的涡环状态。还与相同几何形状的刚性转子产生的流量进行了比较。