An Improved Process for Turbine Shroud Optimization in the Preliminary Design Phase

Abstract

Larger turbine shroud will result in lower tip leakage losses but will increase the rotor mechanical stresses; hence optimization is necessary, especially at the preliminary design of the engine. The improved process developed is as follows: from blade and shroud geometry, the algorithm performs several 3D mechanical analyses in finite element software, allowing the calculation of interpolations to finally extract the largest shroud size. The relative deviation on stress between the 3D new software analysis and the existing process does not exceed 4%, which is acceptable for the preliminary design. In addition, the time saved is considerable: 10 minutes for the existing process as opposed to 1 minute for the lighter simulations. This new optimization method shows that a local and targeted dimensioning, limiting the number of parameters and constraints, responds quickly and precisely to the problem. However, the choice of variable parameters is crucial, hence the importance of the influence of the parameters. This optimization method contributes to the preliminary design phase of the shroud to reduce the design time and gain in accuracy while ensuring the robustness of the process, therefore in the logic of the development of a full Preliminary Multidisciplinary Design Optimization (PMDO) system for the turbine design.