Structural excitation and direct production of acoustic sources in the flow lead to the sound emission of side channel blowers. Pressure fluctuations in the region of the interrupter excite the structure and result in a tonal sound emission at the blade passing frequency (BPF). Furthermore the flow phenomena produce acoustic sources that are radiated in the far field. These different mechanisms of the structural and acoustic excitation are calculated in a simplified way. In a second step each source is separately coupled into the side channel blower. The structural excitation is realized with a shaker. The acoustic sources are generated with a horn driver (speaker) and are induced into the system through the outlet of the blower. Using this setup, the contribution of each source to the tonal sound in the far field can be estimated and compared to the total measured sound pressure level (SPL) at the corresponding frequency.
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