Authors: Nobuhiko Yamasaki Hirotoshi Tajima
Publish Date: 2008/07/09
Volume: 17, Issue: 2, Pages: 163-169
Abstract
In the wakerotor interaction fan noise a number of the interacting modes at the blade passing frequency BPF and its harmonics are generated which are prescribed by the number of stator and rotor blades etc In the present study the dominant mode is tried to be suppressed by the secondary sound from the loudspeaker actuators One of the novel features of the present system is the adoption of the control board with the Field Programmable Gate Array FPGA hardware and the LabVIEW software to synchronize the circumferentially installed loudspeaker actuators with the relative location of rotational blades under arbitrary fan rotational speeds The experiments were conducted under the conditions of three rotational speeds of 2004 3150 and 4002 rpm The reduction in the sound pressure level SPL was observed for all three rotational speeds The sound pressure level at the BPF was reduced approximately 13 dB for 2004 rpm case but not so large reduction was attained for other cases probably due to the inefficiency of the loudspeaker actuators at high frequencies
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