This paper presents an experimental investigation of a propeller operating at low Reynolds numbers and provides insights into the role of aerodynamic flow features on both propeller performances and noise generation. A propeller operating at a tip Reynolds number regime of $4.3\times {10}^4-4.38\times {10}^4$ is tested in an anechoic wind tunnel at an advance ratio ranging from 0 to 0.6. Noise is measured by means of a microphone array, while aerodynamic forces are measured with load and torque cells. Oil-flow visualizations are used to show the flow patterns on the blade surface, whereas phase-locked stereoscopic particle image velocimetry (PIV) measurements are carried out to analyze the flow at 60% of the blade radius. The pressure field around the blade section has been computed from the PIV velocity data. Results reveal a complex flowfield with the appearance of a laminar separation bubble at the suction side of the blade. The separation bubble moves toward the leading edge and reduces in size as the advance ratio decreases. At an advance ratio equal to 0.6, the flowfield is characterized by a laminar separation without reattachment. This causes vortex shedding responsible for a high-frequency hump in the far-field noise spectra.

本文介绍了在低雷诺数下运行的螺旋桨的实验研究，并提供了对空气动力学流动特征对螺旋桨性能和噪声产生的作用的见解。在尖端雷诺数制度下运行的螺旋桨$4.3\times {10}^4-4.38\times {10}^4$在消声风洞中以 0 到 0.6 的超前比进行测试。噪音是通过麦克风阵列测量的，而空气动力是通过负载和扭矩传感器测量的。油流可视化用于显示叶片表面的流动模式，而锁相立体粒子图像测速 (PIV) 测量用于分析叶片半径 60% 处的流动。叶片部分周围的压力场已根据 PIV 速度数据计算得出。结果揭示了一个复杂的流场，在叶片的吸力侧出现层流分离气泡。分离气泡向前缘移动并随着前进比减小而尺寸减小。在推进比等于 0.6 时，流场的特点是层流分离而不会重新附着。