No. 106, 2000, 45-68

A theoretical model of 3D flutter in subsonic, transonic and supersonic inviscid flow


A three-dimensional nonlinear time-marching method for aeroelastic behaviour of oscillating turbine blade row has been presented. The approach is based on the solution of the coupled fluid-structure problem, where the aerodynamic and structural dynamics equations are integrated simultaneously in time, thus providing the correct formulation of a coupied probiem as the interblade phase angle at which stability (instability) would occur is also 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 hybrid H2O (or H- H) grid. 

The structural model is based on the 3D and 1D models. In 3D model the mode shapes and natural frequencies have been obtained via standard FE analysis techniques. The 1D blade model applied here is a one dimensional beam described by an extended beam-theory including all important effects on a rotating blade. The fluid and the structural equations are solved using the direct integration method or the modal superposition method. The fluid-structure model is also presented for a very simple two degree of freedom blade model.


Euler equation, unsteady transtonic flow, blade assembly


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