Hamid Reza Talesh Bahrami - School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran
Sajad Ghasemlooy - Malek Ashtar University, Tehran, Iran
hamid Parhizkar - Malek Ashtar University, Tehran, Iran

Rotating cylinders have wide applications in different areas, especially the aerodynamic area. However, the acoustic behaviors of these components have not been widely studied. The generating noise from a spinning cylinder is mainly due to the detached vortices from the leeward of the body. In this study, the large eddy simulation technique is used to simulate the flow field over a three-dimensional cylinder. In the following, the Ffowcs Williams and Hawkings equation is used to estimate the noise at the specified locations using the oscillating pressure components on the cylinder wall. The acoustic behavior of both stationary and rotating cylinders are studied. Results show that the acoustic behaviors of cylinders rotating with smaller frequencies (up to f=۱۶f۰, where f۰ is the dominant detaching frequency of vortices on a stationary cylinder) are nearly the same. However, at higher rotational frequencies (۲۴f۰) where vortices are omitted, OASPL of the generated noise is reduced considerably (about ۲۰ dB at different angles with constant radial positions, r=۲۶D, at mid-span plane). On the other hand, when the rotational frequency is increased over this limit, the pressure oscillation on the wall becomes significant and the OASPL approaches higher values.

: Rotating Cylinder, Aerodynamic Noise, Large Eddy Simulation, Ffowcs Williams and Hawkings, Acoustic