Low-speed voluteless centrifugal fans are typically used in ven la on systems. The nega ve side of the fans is noise, par cularly tonal noise of which the dominant tone is at the blade passing frequency (BPF). One of the important noise contributors is the gap between the rota ng shroud and the sta onary inlet duct. Previous studies have shown that the flow passing through the gap causes turbulence that interacts with the blade leading edge (BLE), rendering surface pressure fluctua ons that are the tonal noise sources at BPF. In this study, a method of assembling micro vortex generators (MVGs) to control the turbulence for voluteless centrifugal fans is proposed for the first me. The assembling is made in two different ways: 14 add-ons on the shroud surface at the gap, and 7 ones on the BLE surface near the shroud. The effects of the MVGs are inves gated using the hybrid computa onal aeroacous cs method, which couples the improved delayed detached eddy simula on method with the Ffowcs Williams and Hawkings acous c analogy. Our simula ons show that the MVGs are effec ve to control the turbulence and mi gate the tonal noise. The assembled array of 7 MVGs achieves more reduc on of the tonal noise than the 14-MVGs array.