Abstract: As an inert gas fire extinguishing system for protecting the fire safety of engine room of data centers, the high-intensity noise generated by the high-pressure inert gas sprayed from its nozzle during a fire can cause irreversible damage to a large number of mechanical hard drives in the data center. This article studies the overall noise intensity (Z-weighted) of existing inert gas nozzles during the spraying process and their noise intensity distribution in different frequency ranges. It is found that the generation of noise is mainly related to the relative flow velocity and flow state of the gas at the nozzle orifice. It has been verified through experiments that adding a loose and porous outer cover to the nozzle can effectively reduce spray noise, and optimizing the shape of the outer cover can further suppress high-frequency spray noise. Finally, the nozzle end pressure was achieved within the range of 0 MPa to 3 MPa, and the full frequency noise level was controlled below 100 dB, with good noise reduction effect, effectively ensuring the safety of the storage hard disk in the data center room during the operation of the inert gas fire extinguishing system, and having good application prospects.

Key words: data center engine room, gas fire suppression, noise-reducing nozzle, hard disk drive (HDD), noise reduction performance