Abstract
The noise generated by the interaction of the turbulent wake of the fan with the Outlet Guide Vanes (OGV) is a major component of turbofan engine noise. The development of noise reduction concepts applied to the OGV is an intensive research topic, with some current effort dedicated to an active solution making use of piezoelectric actuators integrated within the OGV airfoils to control the surface impedance. In order to define target values for the impedance that would lead to significant noise reduction over a chosen frequency range, a numerical method is being investigated in the present work. The method relies on solving the linearized Euler’s equations in the frequency domain around an airfoil and introducing a velocity fluctuation representing the fan’s turbulent wake upstream of the airfoil. An impedance boundary condition can be applied to the airfoil surface, and optimal values could be found through a parametric study. This paper presents the first set of 2D simulations that were performed to assess the capability of the method to show the effects of an impedance on the airfoil acoustic response, by comparison with a rigid one.
