Automatic Thermal and Stress Preliminary Analyses Applied to a Turbine Rotor

A gas turbine engine design is a multidisciplinary iterative process requiring an efficient interaction between each discipline tool and process in order to find the best compromise satisfying all the conflicting domains... [ view full abstract ]

A gas turbine engine design is a multidisciplinary iterative process requiring an efficient interaction between each discipline tool and process in order to find the best compromise satisfying all the conflicting domains involved. It has been proved that it is extremely difficult to correct an unsatisfactory concept at a detailed design phase of an engine. The use of Multidisciplinary Design Optimization techniques at a preliminary design phase (Preliminary MDO or PMDO) allows correcting this. PMDO system implementation requires bringing as much knowledge as possible in the early phases of the design where the freedom to make modification is at a maximum. This imposes the use of higher fidelity tools that communicate effectively with each other. Considering the impact of the turbine tip clearance on an engine’s efficiency and on preventing blades wear, an accurate tool to predict the tip gap is a mandatory step towards the implementation of a full PMDO system for the turbine design. Tip clearance calculation is a good candidate for PMDO technique implementation considering that it implies various analyses (i.e. transient and steady state thermal and stress analyses) that have to be conducted on the rotor and stator to evaluate the turbine’s components’ size variation during a flight mission. As a first step to the development of such tip clearance calculator satisfying PMDO principles, the present work explores the automation feasibility of the whole analysis phase of a turbine rotor preliminary design process and the potential increase in the accuracy of results and time gains. The proposed conceptual system integrates a thermal boundary conditions (BCs) automated calculator and interacts with a simplified air system generator and with several conception tools based on parameterized CAD models (one for each rotor component). The project is divided into three phases. The first phase develops the implementation methodology of the thermal BCs calculator. The second phase describes the analyses set up: importation of the conception tools geometry as well as the air system network and the mission conditions, automatic meshing of the turbine components, and application of the thermal BCs. The third phase is the results’ numerical validation. This work led to great improvements compared to a regular conceptual tool while being faster than the detailed design one used as a target. By requiring fewer inputs, this system decreases the risk of human errors while entirely leaving the important decisions to the user. Finally, the procedures’ simplifications coming with such system demonstrate that one engineer is able to design a whole turbine rotor from its components geometric design to the analyses’ results post-processing.