How to Control Noise in Long-Shaft High-Temperature Fans Using Technology

How to Control Noise in Long-Shaft High-Temperature Fans Using Technology

Anyone who has used a long-shaft high-temperature fan knows that they can be very loud. While noise from these fans is unavoidable, it can have a significant impact on the surrounding environment, making it necessary to take measures to mitigate this impact. Let’s explore some methods for controlling noise in long-shaft high-temperature fans using technology. The noise level of a long-shaft high-temperature fan depends not only on its construction but also on its operating conditions (determined by total pressure and airflow). Noise levels vary depending on the fan series and model. Under different operating conditions, even fans of the same class will produce lower noise levels when operating at their high-efficiency point. To better characterize the noise performance of long-shaft high-temperature fans, a concept more precise than the A-weighted sound level has been developed. The specific A-weighted sound level refers to the sound level generated by the fan per unit airflow (1 m³/min) and per unit total pressure (1 mm water column). The specific A-weighted sound level of the same long-shaft high-temperature fan varies under different operating conditions. At higher efficiency points, the specific sound level will be lower. Under rated operating conditions, the specific A-weighted sound levels of fans from different series exhibit distinct noise characteristics. Therefore, the A-weighted sound level is currently regarded as the noise limit indicator for long-shaft high-temperature fans both domestically and internationally. Fans of different models within the same series share the same A-weighted sound level. The higher the manufacturing precision of a long-shaft high-temperature fan, the better its aerodynamic performance, and the lower its sound level. A common method for controlling fan noise is to install passive noise suppressors at the inlet and outlet of the long-shaft high-temperature fan. In situations requiring high noise reduction, sound-absorbing and sound-insulating enclosures can be used, which may be equipped with impact-absorbing materials. Through these methods, significant noise reduction can be achieved. In China, there are many noise control equipment manufacturers capable of reducing noise and vibration in various types of long-shaft high-temperature fans. Technologically, however, effective suppression of noise issues in China’s centrifugal fans has led to the emergence of low-noise fans. Although noise reduction devices are available for long-shaft high-temperature fans, there are cases where such devices cannot effectively reduce noise in fans with special requirements. Therefore, technological upgrades are needed, and further research is warranted.