The influence of helix angle and gears width on the noise radiated by a gearbox

The noise spectrum generated by a gearbox depends on multiple factors, such as gear design parameters, casing geometry, rotational speed of the shafts and the presence of imperfections. This numerical study analyses the influence of the helix angle and gear width on the noise radiated by a gearbox through parametric studies. The numerical investigation combines a time-domain analysis on a multibody model of the gearbox with a frequency-domain analysis on a boundary element model of the air to evaluate noise radiation in an open space in free-field conditions. The simulations assume a constant workload and a constant rotational speed of the shafts. The results indicate that increasing the helix angle and gear width leads to a smoother noise spectrum and modifies its shape. Compared to spur gears, helical gears generate lower sound power levels due to a reduced variation in the meshing stiffness.