Noise generation by rotating blades in a riding lawnmower

Measurements presented at the Acoustical Society of America Meetings in Newport Beach, CA in December 2000 showed that the dominant source of noise radiated from our riding lawnmower is the mower deck and that most of this noise is radiated directly as airborne noise from under the mower deck. In this paper, results from measurements of unsteady pressures on the tips of mower blades and baffling under the deck are presented. Frequency spectra are presented along with fluctuations in the pressure versus blade position. Measurements were conducted on three types of blades (flat, standard, and mulching) located at each of the three blade positions under the deck. To quantify the affects of the interaction between blades, measurements were conducted with one instrumented and two noninstrumented blades installed, and with only the instrumented blade installed. Results from these measurements are presented and discussed.