Numerical Modelling of the Aeroelastic Behaviour and Variable Loads for the Turbine Stage in 3D Transonic Flow

• Published in: Journal of thermal science 2005-09, Vol.14 (3), p.236-241
• Main Authors: Gnesin, V. I., Kolodyazhnaya, L. V., Rzadkowski, R.
• Format: Article
• Language: English
• Subjects: 数字模型; 涡轮机; 空气弹性形变; 跨音速流动
• ISSN: 1003-2169; 1993-033X
• DOI: 10.1007/s11630-005-0007-1

In this study presented the algorithm proposed involves the coupled solution of 3-D unsteady flow through a turbine stage and the dynamics problem for rotor-blade motion by the action of aerodynamic forces, without separating the outer and inner flow fluctuations. The partially integrated method involves the solution of the fluid and structural equations separately, but information is exchanged at each time step, so that solution from one domain is used as a boundary condition for the other domain. 3-D transonic gas flow through the stator and rotor blades in relative motion with periodicity on the whole annulus is described by the unsteady Euler conservation equations, which are integrated using the explicit monotonous finite-volume difference scheme of Godunov- Kolgan. The structural analysis uses the modal approach and a 3-D finite element model of a blade. A calculation has been done for the last stage of the steam turbine, under design and off-design regimes. It is shown that the amplitude-frequency spectrum of blade oscillations contains the high frequency harmonics, corresponding to the rotor moving past one stator blade pitch, and low frequency harmonics caused by blade oscillations and flow nonuniformity downstream from the blade row; moreover, the spectrum involves the harmonics which are not multiples of the rotation frequency.