Fundamentals of Noise in High-Temperature Stainless Steel Fans

Fundamentals of Noise in High-Temperature Stainless Steel Fans

I. Overview of Side-Measurement Techniques for High-Temperature Stainless Steel Fan Noise Fans (commonly referred to as "blowers") are extensively used across industries including metallurgy, petrochemicals, machinery, construction, light industry, electronics, and mining. During operation, these fans transmit intense acoustic noise through intake ports, housings, ductwork, and other components into surrounding spaces. This not only harms the physical and mental health of workers but also pollutes the environment. High-temperature stainless steel fan noise has now become a primary source of noise pollution. To effectively protect workers and the environment, it is essential to control the scope and severity of fan noise impact. Developing low-noise high-temperature stainless steel fans that meet permissible standards requires addressing their noise emissions. Sound measurement is a critical step in this noise control process. For instance, when constructing large boiler rooms, design considerations must address how to control the noise from high-temperature stainless steel fans. To enable operators to communicate easily without interference from operational fan noise, the fan room and control room must possess sufficient sound insulation. The specific noise reduction value depends on the difference between the fan room's A-weighted sound level and the permissible A-weighted sound level in the control room. Additionally, the intake of the high-temperature stainless steel fan and the exhaust of the induced draft fan are open to the atmosphere. Fan noise inevitably radiates from these openings, causing significant disturbance to the surrounding environment. Therefore, installing silencers at appropriate locations on the inlet of the high-temperature stainless steel fan and the outlet of the induced draft fan is required. This significantly reduces fan noise, with the total required attenuation determined by the difference between the A-weighted sound levels at the fan inlet/outlet and the permissible A-weighted sound level in the surrounding environment. We can see that from the outset, it is necessary to consider the sound pressure levels near the high-temperature stainless steel fan and induced draft fan, as well as the sound pressure levels at the inlets/outlets across eight octaves. Based on the actual acoustic conditions, optimal design parameters are selected. Through comparative analysis, a reasonable sound insulation and noise reduction solution is chosen, all of which necessitate repeated basin testing. Upon completion of the boiler room, whether the installed sound insulation and noise reduction equipment meets design requirements is also evaluated through A-weighted measurements. For instance, when developing a high-efficiency, low-noise fan, it is first necessary to understand the sound levels of similar fans domestically and internationally. This requires conducting acoustic measurements on the fan. During prototype and sample testing, large-scale acoustic testing must measure how blade geometry, impeller structure, air tongue clearance, rotational speed, and other parameters affect fan noise. After fan commissioning, acoustic testing must verify whether surface sound levels meet design specifications. The national standard "Acoustic Measurement Methods for Fans and Roots Blowers" provides a unified acoustic testing methodology for all fan manufacturers and relevant testing institutions.