Fe Analysis of a Steam Turbine HP Rotor Blade Stage Concerning Material Effort, Dynamic Properties and Creep Damage Assessment

Abstract

This paper is concerned with the 1 st stage of HP rotor blade assembly steam turbine TK 120. The methodology was focused on the selection of mechanical properties and the way of the rotor disc modeling and estimating the degree of damage caused by creep. Then the dynamic interference between the frequencies of excitation and the natural frequencies was assessed. Static calculations were performed for the cyclic sectors consisting of the disc, disc blades, spacers and shrouding, including loads as temperature, mass forces from the angular velocity and the pressure on the blades. Then, the creep analysis using a Norton's model and the modal analysis were performed. Static analysis gave information concerning the distributions of displacements, stress and strain components. In the creep analysis, the creep displacements and stress relaxation versus time were determined and the estimated degree of damage caused by creep was evaluated at each part of the rotor disc. In the modal analysis, the natural frequencies and modes of vibrations corresponding to the nodal diameters were found. The results of modal analysis were shown in the SAFE graph. Numerical calculations have shown that the rotor disc was a well-designed structure and did not reveal any dynamic interference.

Finite Element Modeling of Material Fatigue and Cracking Problems for Steam Power System HP Devices Exposed to Thermal Shocks

“…In this area, a fracture appeared in the radial direction around the circumference of the rotor, which propagated into up to 40 mm. Because the turbine was in good dynamic condition (measured and verified analytically [18][19][20]), the damage could not be caused by a lack of balance. The cause was suspected to be of thermal nature, because according to Fig.…”

Experimental Investigation and Modeling of Damage Accumulation of EN-AW 2024 Aluminum Alloy under Creep Condition at Elevated Temperature

“…Robinson’s rule is then used to sum the creep damage [ 36 ] derived from the Palmgren–Miner fatigue hypothesis: where t fi denotes the time to failure under defined conditions. This model was used by Borkowski et al [ 37 ] to determine damage to steam turbine blades and by Loghman and Moradi [ 38 ] to analyze creep effects in a thick-walled spherical reactor. The work of Hu et al [ 39 ] shows the strain form of Relationship (7) by replacing the time values with the corresponding strains.…”