Abstract by Michael Rose
Physics and Astronomy
Noise reduction of vacuum-assisted toilets
Flushing an aircraft toilet generates noise levels that can be disturbing to both users and passengers near lavatories. This work presents a noise reduction retrofit. There are three noise characteristics to each flush which correlate to the valve: an initial noise level peak from the flush valve opening, an intermediate noise level plateau associated with the valve being fully opened, and a final noise level peak associated with the flush valve closing. It was hypothesized that increasing the distance between the flush valve and the bowl and increasing the bend radius of the tube at the bowl exit would reduce overall noise levels. These modifications resulted in a 13 to 16 dB reduction in the noise radiated from the bowl during the valve opening and closing in addition to a 5 to 10 dB reduction in the noise radiated from the bowl during the open valve condition. The presentation also discusses intermediate results of varying tube length and bend radius on the radiated sound levels which gives insight into the noise generation mechanisms.