Twin-Web Turbine Discs: Part 1 — Design and Analysis of Their Efficiency

Abstract

Part 1 of this work discusses the numerical results of the performance efficiency investigation conducted for twin-web (hollow) discs in terms of stress and mass reductions. Three typical turbine discs and one small-sized turbine blisk are analysed using parameterised finite-element models and the modern methods of multi-criteria optimisation. The discs and blisk have different overall sizes and load conditions (rotation speed [rpm]), thermal state, blade load, etc.). The design of disc variants with a split in the hub is also considered. This option will help to simplify the manufacturing technology and improve design efficiency. An analysis of the results shows that a twin-web turbine disc design permits increases in turbine disc strength as well as decreases in its mass. The extent of these advantages depends on the overall size of the disc and its rpm: a large-sized disc with a relatively low rpm shows a 4% mass decrease and a 15% increase in cyclic life; a medium-sized disc with an average rpm has an 18% mass decrease and a doubled cyclic life; and a small-sized disc with high rpm has a 30% mass decrease and a 2.8 times longer cyclic life. Additionally, a small-sized blisk with a high rpm shows a 60% mass and a doubled cyclic life.