关键词: 非定常流动, 连锁区域, 弯曲薄翼, 旋涡脱落, 自激振动

Abstract: The possibility of self-oscillation of a thin cambered blade, when the attack angle is near its stall angle, is experimentally investigated in a circuit-water tunnel. The vortex-shedding patterns for different attack angles of the blade are visualized by two methods：a twinkle laser sheet and high-speed-camera photography. And the torque acting on the blade is measured using strain gauges. To confirm whether the vortex shedding would induce the self-oscillation of the blade, the blade is subjected to pitching motions, and by changing the pitching frequency and amplitude, lock-in boundaries for certain attack angles are determined. Phase differences between the blade’s pitching displacement and the torque to oscillate it are also investigated, and the probability of self-oscillation of the blade is inferred from these phase differences.

Key words: Lock-in boundary, Self-oscillation, Thin cambered blade, Unsteady flow, Vortex shedding