Method for reducing the vibration levels of a propfan of contrarotating bladed discs of a turbine engine

A method for reducing the vibration levels likely to occur, in a turbine engine including a first and a second bladed disk forming a propfan of contrarotating disks, when the two disks are traversed by a gaseous fluid, because of the turbulence of aerodynamic origin generated by the second bladed disk on the first bladed disk is disclosed. The method includes defining an initial configuration of the blades, calculating the synchronous forced response on the first bladed disk as a function of the harmonic excitation force generated by the second bladed disk expressed as a linear function of the generalized aerodynamic force for the mode in question; for stacked sections of one of the two disks, determining a tangential geometric offset value of the individual aerodynamic profile to reduce the term corresponding to the generalized aerodynamic force; and applying a new configuration to the blades.