Strength analysis of disc rotor heavy-duty gas turbine considering bolt pretension load

In the last years, heavy-duty gas turbine has been increasingly used as high efficiency systems for heat and power generation. The typical size of these powerplants mainly consist compressor, turbine and combustor. And the rotor disc assembly structure is different from the single whole rotor structure. Several computer codes have been developed to analyse the strength of the rotor. In the present paper, a heavy-duty gas turbine rotor system consists of seventeen stages of a compressor and four stages of a gas turbine. The front three stages compressor discs are forged into one single part and the other compressors are individual discs. The gas turbines have four individual discs which having teeth of a bevel gear are juxtaposed to engage the teeth. With the central or circumferential tie-rods fastened, stages of gas turbine are combined as a single construction by jointing faces form teeth. The teeth correspond to bevel gears having an apex angle of 180 degrees and are engaged to transmit a torque and to align the discs. As the construction of the modern gas turbine sets is sufficiently complex, it was expedient to use approximation methods of computation. One of the most urgent problems during design and manufacturing of gas turbine units is the provision of reliability and durability of unit's joints by development and application of perspective turbo machines constructions with application of up-to-date CAD/CAE/CAM-technologies. This code is based on the simplified 3d-dimensional model of different types of rotor structure (central and circumferential). The effects due to bolt pretension load of the rotor are also taken into account in the model. And the code is based on Green-Lagrange strain from the bolt pretension load force to initial stress and strain to calculate the stress stiffness of the rotor. This paper is devoted to finite element overall strength analysis of rotors considering the bolt preload effect, and the principle of the axial preload force is determined. The geometry structure parameters which affect the rotor strength are investigated. Moreover, this work is very important in practical design of the heavy-duty gas turbine tie rod disc rotor.