Experimental and numerical investigation of unsteady flow around cylinder with four plates perpendicular to it with the rotational degree of freedom

In this study, the behavior of a subject consisting of a cylinder with ۴ plates perpendicular to it with a rotational degree of freedom under airflow both through the numerical approach, known as improved discrete vortex and experimental approach were investigated. The experimental and numerical results have shown that oscillating regime occurs in low velocity and length. This movement is vibrations with irregular range around an equilibrium angle of ۴۵ degree. In oscillating motion regime, it is seen that after releasing the object in free flow, a high torque force, due to the flow’s acceleration from the model, is induced to the plates and makes a big angular change, but after a while, the range of oscillation around the equilibrium angle of ۴۵ degree decreases. The probability of rotational motion regime in length ratio of one and velocity of ۱۳ m/sec in initial angle of attack is low. However, the experimental and numerical results have indicated that still in high initial angle of attack around ۴۵ degree, owing to the induced decreased torque to plates, there exists an oscillating movement. Rotational regime in length ratio of ۳ and free flow velocity ۱۳ m/sec in all initial angle of attack is observed. In addition, rotational regime appears in all initial angle of attack with the length ratio of ۴ and different free flow velocities because of increase in the area of plates.

Keywords:

Unsteady flow , Vortex Panel Method , Rotational and Vibrational motion , Forced Vibration , Wind Tunnel Tests