Disc Design and Air System Comparison Between a Single and a Two Stage High Pressure Turbine Aero Engine

Abstract

The design of the high pressure turbine (HPT) module of an aero engine and the method used to predict disc life and burst margin are different among the manufactures. In this paper, two different disc design methods are presented and compared, namely, the strain instability and the Chambers methods. The results of the disc study show that the strain instability method introduces low disc weight compared to the Chambers method. Both methods satisfy the burst speed requirement of 125% of the red line limit speed. The strain instability method was applied to design the disc of a single stage (SS) and of a two stage (TS) HPT configuration. The design philosophy of the SS is to run the HPT with a high rpm and a low SOT, whereas the TS design is based on low rpm and high SOT. The disc preliminary design considered the mechanical boundary conditions only without a temperature gradient. The total boundary conditions (thermal and mechanical) were then applied to the detailed disc design. A comparison between the two applied air systems of the SS and the TS design configuration was also performed. In comparing the two, the SS presents a design with low cooling air consumption, and it is also found that a cover plate is necessary for the front side of the SS configuration. The results of this study could be useful for the design engineer to know how and what is needed to accomplish a safe and effective design. Complementary thermal and structural tests should be performed to identify the limits and benefits of each approach.