Acoustic modulation effect of rotating stator/rotor interaction noise

Anthony Gerard , Stéphane Moreau , Alain Berry (1) , Patrice Masson

1 UdeS - Département de génie mécanique [Sherbrooke]

Tonal noise from fans mainly comes from the periodic unsteady blade forces and/or vane forces due to the interaction between the rotor and its environment. To distinguish the different interactions leading to tonal noise in the acoustic spectrum, this paper presents an original method consisting of slowly rotating a quasistatic part (e.g. a stator). An analytical model based on the Lowson model has been developed to take into account relative rotation motions between a number of rotors. This model shows that the acoustic radiation due to the interaction between a rotating stator and the rotor shifts in the spectrum at frequencies nB\Omega ₁ \pm w\Omega ₂, where n is the harmonic order, B is the number of rotor blades, \Omega ₁ is the angular velocity of the rotor, \Omega ₂ is the angular velocity of the moving “quasistatic part” and w is the order of the unsteady forces decomposed in circumferential Fourier series. Using this modulation effect, every circumferential mode w radiates at different frequency in the acoustic spectrum. The radiation due to the interaction between the rotor and all the other static components remains at frequencies nB \Omega ₁. This modulation effect can be used to acoustically optimize stator.

Domaines: Acoustique [physics.class-ph]

Anthony Gerard, Stéphane Moreau, Alain Berry, Patrice Masson. Acoustic modulation effect of rotating stator/rotor interaction noise. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810832⟩