Local contribution of blades vibration on the choke flutter instability in transonic UHBR fan

International audienceIn this paper, an Ultra High Bypass Ratio fan is analyzed using a time-linearized Reynolds-Averaged Navier-Stokes equation solver to investigate the choke flutter. Simulations have been performed on a 2D blade to blade extraction. The steady flow exhibits a strong shock-wave which chokes the blade to blade channel. A flow separation zone can be noticed near the shock-wave on the suction side. The inter blade phase angle (IBPA) and the reduced frequency have been set to obtain a case with a choke flutter instability. The blade is decomposed in 424 subsections to track the contribution of local vibration to the global damping. Results analysis point to a restricted number of excitation sources at the trailing edge which induce a large part of the work exchange on a limited region of the airfoil. Main phenomena suspected are the shock-wave motion and the shock-wave / boundary layer interaction