The Open Mechanical Engineering Journal

2013, 7 : 48-57
Published online 2013 October 18. DOI: 10.2174/1874155X01307010048
Publisher ID: TOMEJ-7-48

Aeolian Tones Radiated from Flow Over Bluff Bodies

Mohamed Sukri Mat Ali , Sheikh Ahmad Zaki Shaikh Salim , Mohamad Hafz Ismail , Sallehuddin Muhamad and Muhammad Iyas Mahzan
Wind Engineering Laboratory, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Kuala Lumpur, Malaysia.

ABSTRACT

Bluff body is a simple but a central shape for many engineering applications. The geometry shape of the bluff body characterises the behaviour of the flow over the bluff body, where a more complex flow structure is found near downstream. Shear layer separation is mainly responsible for the periodic global phenomena, that includes the generation of sound. The magnitude of the aerodynamically generated sound is dominated by the fluctuations of aerodynamics forces, i.e., drag and lift. The study also shows that the sound pressure field is shaped by the aeolian tones that is related strongly to the lift fluctuations of the bluff body. Amplitude and frequency of the fluctuating lift change naturally with the shape of a particular bluff body. Triangular cylinder exhibits the largest sound pressure level (41.9 dB) followed by ellipse and circular shapes. Square cylinder emits the lowest sound pressure level (36.7 dB). This corresponds to the longest downstream vortex formation length at which for a square cylinder the long vortex formation length provides space for more vortex to dissipate.

Keywords:

Bluff body, Passive flow and noise control, Aeolian tones.