Reduction of Occupational Noise Exposure Using Multiple-Jet Nozzles

沈紹青 ； 林芝衣

《中華民國振動與噪音工程學會論文集》 2007 (2007/06) Pp. 105-114

https://doi.org/10.30028/CSSVANNUAL.200706.0105

並列摘要

The purpose of this work is to investigate the feasibility of using a multiple-jet nozzle to replace a single-jet nozzle with the same total exit area as a noise-control option. Because the majority of the power of noise produced by a nozzle with small exit resides in the frequency range that is not considered in the evaluation of occupational exposure, reduction of exit diameter and increase of noise frequency content will move a significant portion of sound energy into the range that are not directly harmful to human hearing. This approach, compared with other noise-abating methods for industrial noise, is less sensitive to other modifications of nozzle design. In this work, nozzle exit diameters are varied in two ways. In the first, we fixed the exit diameter of the multiple-jet nozzle, while single-jet nozzles with various total exit areas are chosen for comparison. In the second group of tests, we fixed the ratio of the exit diameter of single-jet nozzles to those of multiple-jet nozzles, that is, the number of jets of the multiple-jet nozzles is fixed. The purpose is to understand if the diameter-ratio is the sole factor that influences the effectiveness of multiple-jet approach. The results show that reduction of noise exposure levels is not related to the exit diameter ratio in a linear way. As the exit diameter is getting smaller, the effect of using smaller exit diameters become more pronounced. Use of a multiple-jet nozzle is a viable approach for reducing worker's exposure to noise produced by industrial nozzles. It is easy to implement and effective over a wide range of working conditions. However, the high-frequency noise associated with its use might be the source of other types of hazards.

並列關鍵字

Jet noise ； multiple-jet nozzle ； noise control