Optimum design of inhomogeneous non-uniform rotating discs

Abstract

Gas turbine discs work mostly at high temperature gradients and are subjected to high angular velocity. High speed results in large centrifugal forces in discs and simultaneous high temperature reduces disc material strength. Thus, the latter effects increase deformation of the disc automatically. In order to attain a certain and reliable analysis for disc and to derive corresponding stress distribution, solution should consider changes in material specifications caused by temperature. To achieve this goal, an inhomogeneous disc model with variable thickness is considered. Using the variable material properties method [J. Pressure Vessel Technol. 119 (1997) 264; Thermoplastic analysis of inhomogeneous rotating disk with variable thickness, Proceedings of the EMAS Conference of Fatigue, Camdridge, England, April 2000; Int. J. Pressure Vessels Piping 71 (3) (2001) 285] stresses are obtained for a disc under rotation and steady temperature field. Optimization process begins following stress calculation. Inscribed hypersphere method is used to obtain optimized disc profile. Using the above method, the disc profile is optimized and final solutions are obtained. It is also shown that the solutions of optimization process regarding different initial profiles for disc of similar specifications are unique when inscribed hypersphere radii in the last solution stages are equal. Results are compared to published data and are found to be in good agreement with them.