15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Authors
Abstract
Numerical 3D aerodynamic and aeroelastic assessment using harmonic balance methods has been applied on a last stage steam turbine open test case, which is representative of the aerodynamic characteristics of modern industrial steam turbine transonic blading. The benchmark results showed good agreement with previous research and numerical validation efforts from both academia and industry. In addition, it has been demonstrated that a large part of the numerical design workflows of modern large steam turbine blading, including steady state aero performance calculation using mixing plane, transient blade row interaction, damping predictions, and accounting for complex non-axisymmetric geometric features such as the exhaust hood, can be performed efficiently with the reuse of single passage models. Results from harmonic balance methods are also compared with time-marching transient calculations. The harmonic balance implementation of the solver and used non-reflecting boundary condition methodologies are also explained in detail. Finally, extensive parametric studies and investigations have been carried out regarding different grid topologies, mesh density, the influence of tip gaps and embedded blade row acoustic interactions as manifested in the aerodynamic damping curve close to certain cluster of nodal diameters. The retained number of harmonic modes and effect of vibration amplitude are also checked, in the goal of contributing to a comprehensive validation of the test case.
ETC2023-276
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