The numerical study of 3D flutter in a transonic blade row

A three - dimensional nonlinear time - marching method and numerical analysis of 3D flutter for oscillating blade row has been presented. The approach is based on the solution of the coupled fluid - structure problem in which the aerodynamic and structural dynamic equations are integrated simultaneously in time, thus providing the correct formulation of a problem, as the interblade phase angle at which a stability (instability) would occur is a part of solution. The ideal gas flow around multiple interblade passages (with periodicity on the whole annulus) is described by the unsteady Euler equations in conservative form, which are integrated by using the explicit monotonous second - order accurate Godunov - Kolgan finite - volume scheme and moving grids. In he structure analysis the modal approach is used. The natural frequencies and modal shapes of the blade were calculated by using the different models: 3D finite element model; 1D blade model is of a one-dimensional beam described by an extended beam-theory including all important effects on a rotating blade.