Optimum design of rotational wheels under transient thermal and centrifugal loading.

Abstract

Turbine rotors and compressor rotors are subject to centrifugal and thermal loads. These loads increase proportionally with tip speed and gas temperature. Additionally, rotor weight must be decreased to improve rotor dynamics and to restrict bearing load. Thus, an optimum design technique which offers the lightest possible wheel shape under the stress-limit restriction is required. This paper introduces an optimum design system developed for turbomachinery rotors, and discusses several applications. The sequential linear programming method is used in the optimizing process, and unsteady state thermal analyses of variable thickness wheels are performed using a numerical analysis of a multiring model. Centrifugal and thermal stress analyses of these wheels are performed using Donath's method with the same multiring model. This optimum design program is applied to the design of axial flow compressor wheels. Finally, the validity of these applied results are confirmed by transient thermal and stress analyses using the finite element method.