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Dimensional analysis and scaling of the aerodynamic noise produced by idling circular saw blades.
Keltie-RF; Reiter-WF Jr.
ASME Publication No. 76-WA/DE-11, New York: American Society of Mechanical Engineers, 1976 Dec; :1-12
Dimensional analysis was used to assess the aerodynamic noise produced by idling circular saw blades. The parameters relating the sound produced by the idling saw to the fluid dynamic characteristics of saw blade geometry and kinematics were the sound power and frequency, tip speed, gullet depth and diameter, the distance between gullets, blade thickness and radius, air density, and dynamic viscosity. These ten parameters were combined with the speed of sound in air in a dimensional matrix in terms of mass, length, and time to yield an equation describing eight dimensionless groups. Acoustic measurements made from three locations in a semireverberant laboratory during the operation of a saw stand with and without slotted disks were used to establish the appropriate scaling laws based on the dimensionless groups. The range of test speeds was 1,200 to 3,600 rotations per minute (rpm) as determined by the range of tip speeds reported for saw blades under idling conditions. Strouhal and Reynolds numbers were determined for each slotted disk at the upper and lower frequencies of each operating speed, and the results were discussed in relation to blade tip speed, blade thickness, sound power versus speed behavior, gullet geometry, and conformation to curve fit and scaling laws. Application of the dimensional analysis to determination of the sound produced by a 100 tooth, 450 millimeter (mm) diameter steel tooth saw, 2.44mm thick with triangularly shaped teeth yielded good agreement between the predicted and experimentally derived sound pressure levels.
NIOSH-Grant; Noise-induced-hearing-loss; Noise-analysis; Noise-frequencies; Industrial-noise; Noise-levels
Mechanical and Aerospace Engr North Carolina State Univ 3182 Broughton Hall Raleigh, N C 27607
ASME Publication No. 76-WA/DE-11, American Society of Mechanical Engineers, New York, New York
North Carolina State University Raleigh, Raleigh, North Carolina
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division