Noise Reduction in the Manufacturing Environment: A Study on Small Jet Geometry Alterations

Abstract

Noise pollution is an identified issue in manufacturing environments. While machines, motion, production, etc. are a large factor in this noise pollution, other sources exist. Often copper tubing is connected to pressurized containers as a make-shift jet stream for reorienting elements on the assembly line. These makeshift jets when working in conjunction create noise pollution. By manipulating the exit of these small jets, it is hypothesized that the noise level can be decreased. Using the National Center for Physical Acoustics (NCPA) at the University of Mississippi, three geometry alterations—deburring the end, creating a converging-diverging nozzle, and flattening the end—were tested on these small jets against a control (that still had the burrs and smaller diameter from the pipe cut) to determine the validity of the hypothesis. The results indicated minimal sound pressure level (SPL) changes for each of the alterations compared against the control. Furthermore, the control appeared to be quieter than all the variables. However, by performing an uncertainty analysis and investigating the volumetric flow rate of the control, two discrepancies were uncovered: the flow rate for the control was less than the variables and the volumetric flow readout had its own amount of uncertainty. It was found that both the deburred and converging-diverging jets eliminated a tonal frequency that occurred with the control jet. However, this difference is negligible; geometric alterations did not vastly change the SPL of the jets. More analysis should be conducted; specifically, a sound level weighting analysis and ideal thrust for part reorientation