Patent ID: 8375698

Claim:
A method for reducing the vibration levels in a turbine engine comprising a first moveable bladed disk and a second moveable bladed disk, forming a propfan of contrarotating disks, because of the turbulence of aerodynamic origin generated by the second bladed disk on the first bladed disk, said method comprising: A—defining an initial configuration of the blades as a function of an expected performance of the turbine engine, with individual aerodynamic profiles of p sections (c 1 , c 2 , . . . cp) stacked radially between a root and a tip of said blades; B—calculating, in a computer, a synchronous forced response y(ω) on the first bladed disk as a function of a harmonic excitation force f(ω) generated by the second bladed disk based on a relation y(ω)=F( τ y υ *f(ω), where F is a linear function of a generalized aerodynamic force τ y υ *f(ω) for a fundamental mode of vibration υ in question; C—defining, in a computer, a coefficient (α<1) of reduction of the synchronous forced response y(ω); D—determining, in a computer, for each of said p stacked sections (c 1 , c 2 , . . . cp) of one of the two disks, a tangential geometric offset value θ of the individual aerodynamic profile so as to reduce a term corresponding to the generalized aerodynamic force associated with the fundamental mode of vibration υ| τ y*f(ω)|, a temporal phase shift φ of an excitation pressure f(ω) being linked to a tangential geometric offset by a relation θ=N excit *φ where N excit is the number of exciter sources; the combination of the p sections with the tangential offsets therefore defines a new configuration of the blades of said one of the two disks; E—calculating, in a computer, a synchronous forced response y′(ω) on the first bladed disk; F—if |y′(ω)|>α*|y(ω)|, repeating, in a computer, the calculation at D with new tangential geometric offset values; G—if |y′(ω)<α*|y(ω)|, manufacturing at least a portion of the blades of said one of the two disks with the new configuration and employing the blades in the propfan; and H—operating the propfan with reduced vibration levels.