Effects of Blades bending on the Flatter speed of Gas Turbine with Timoshenko theory

mohammad amin rashidifar, Darvish Ahmadi, Abbas Rahi

Abstract


In this research paper, a row of blades which consist of a tuned disk and certain number of blades and will be examined. Curved blades that cross a series of free moments of inertia due to bending by cantilevered beams are modeled here. Regarding that the disk being tuned, the whole structural and fluid system analysis is focused on a blade and the current around it. Aerodynamic forces during stable and unstable motion in several steps are calculated using ANSYS / FLOTRAN CFD software and then the real and unreal forces fluid are obtained. On the other hand, the equation of motion in Timoshenko beam is obtained and to determine the system natural frequencies and modes, outside forces are zero and modal analyses while the bending and torsion movements of exposure mode have been done is carried out. By using semi inertia and semi damping and semi elastic of fluid’s elements in inertia and damping and stiffness matrix we can have an eigenvalue equation that solved by using state space method. In this case we can obtain flatter speed of turbine and then, by calculate flatter speed in little bending of blade and compare with previous state effects of blade bending on flatter speed is study. At least bending and torsion deformation are analyzed with respect to time.


Keywords


Blade; Aerodynamics; Flatter; ANSYS CFD; Timoshenko beam

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