On the transferability of probabilistic fracture mechanics results for scaled 50Hz and 60Hz heavy duty gas turbine rotor disks
In the development of heavy duty gas turbines for the energy sector oftentimes the majority of the design work is performed in either the 50 Hz or the 60 Hz size. Many aspects of the designed engine for one market (50 Hz as an example) can then be used to design with significantly reduced effort for the other market (i.e. 60 Hz). For example, most dimensions of rotor components can be geometrically scaled such that centrifugal forces in those massively rotating parts are conserved. This article investigates the transferability of probabilistic fracture mechanics results from one market to the other one. Or in other words: can we perform probabilistic fracture mechanics for the 50 Hz rotor design and deduce the risk of failure for the scaled 60 Hz design (or vice versa)? Multiple challenges must be considered in the transferability including the different volume, surface to volume ratio, as well as the different transient behavior for the smaller 60 Hz design. We address that challenge by building up complexity for a generic rotor design in order to separate the different effects and associated design features. We then discuss several Siemens rotor designs with respect to transferability of probabilistic fracture mechanics results and correlations to deterministic approaches. This work enables the creation of design rules to avoid unnecessary work for scaled 50 Hz/60 Hz market engines and therefore supports the reduction of product development costs.