The effect of the splitter plate on the aeolian tone mitigation

The effects of a fixed splitter plate mounted on the downstream side of a circular cylinder to reduce aeolian tone is investigated experimentally. The diameter of the cylinder D is 22mm. Three parameters are considered: The length of the plates (L=0.5D, 1.0D, 1.5D), the thickness of the plates (h=1mm and 2mm), and the Reynolds numbers (Re = 2.18×〖10〗^4 ~ 4.94×〖10〗^4 ) based on cylinder diameter. The splitter plates achieve the reduction in aeolian tone at the fundamental vortex shedding frequency and the overall sound pressure level (OASPL) for all cases. The peak values of SPL at the fundamental vortex shedding frequency decrease by about 7.3~15.8 dB with splitter plates behind the cylinder, and the OASPL reduction ranges from 5.7dB to 10.5dB. Meanwhile, the fundamental vortex shedding frequency experiences a slight frequency shift, which means the splitter plate has influence on the vortex shedding process. The harmonic tones, including the first and second harmonics, largely disappear when the splitter plates is attached, except for the plate with L=1.5D and h=1mm. Flow fields derived from particle-image velocimetry experiments and the power spectral density of the streamwise velocity are presented, which helps to identify the modification of the near-field flow dynamics by the splitter plate, and connect that to the observed far-field noise reduction.