Development of a fully-coupled harmonic balance method and a refined energy method for the computation of flutter-induced Limit Cycle Oscillations of bladed disks with nonlinear friction contacts

Flutter stability is a dominant design constraint of modern gas and steam turbines. To further increase the feasible space, flutter-tolerant designs are currently explored, which may undergo Limit Cycle Oscillations (LCOs) acceptable, yet not vanishing, level. Bounded self-excited oscillations priori nonlinear phenomenon, can thus only be explained by interactions such as dry stick–slip friction in mechanical joints. The available simulation methods for blade flutter account interactions, at most, one domain, structure or fluid, assume behavior other domain linear. In this work, we develop fully-coupled frequency method capable resolving flow structural effects. We demonstrate computational performance state-of-the-art aeroelastic model shrouded turbine row. Besides simulating limit cycles, predict, first time, phenomenon instability, i.e. , situation where equilibrium point locally stable, but sufficiently strong perturbation (caused e.g. an impact), frictional dissipation cannot bound vibrations. This implies that linearized theory does necessary lead to conservative blades. show due contact tip shrouds, cause change vibrational deflection shape frequency, turn leads loss stability. Finally, extend well-known energy capture these effects, conclude it provides good approximation useful initializing solver.