In order to supply tools for low noise design to the manufacturers of lawnmowers CETIM has set up a research project on blade noise (which is predominant on medium size and big machines). Experimental studies are based on the use of a special test rig which allows to measure blade noise without disturbances from the drive unit and to determine simultaneously the pressure fluctuations generated by the blade.
Numerical simulations using CFD software allow computation of the unsteady pressure field distribution inside the casing, identification of pseudosound perturbations near the blade and localisation of flow recirculation areas near to the casing outlet.
M.Bockhoffa, K.Monesa, Centre Technique des Industries Mécaniques (CETIM), France