Research on Multidisciplinary Design Optimization of Aeroengine Turbine Flow Path in the Preliminary Design Phase

Abstract

The design of an aero-engine is traditionally divided into three levels: conceptual design, preliminary design and detailed design. This three-step design process is inherently iterative, which can slow the design process and overall productivity. Additionally, as an integrated systems engineering analysis, aero-engine design involves multiple-disciplines. The complex coupled-relationship among multiple-disciplines and multiple-components gives rise to severe conflict with performance requirements when designing, especially when it comes to high-performance aero-engine. Traditionally, designers need to empirically balance all kinds of requirements, which lead to a longer design cycle. So it is necessary to apply Multidisciplinary Design Optimization (MDO) to organize and manage the process of design system which sufficiently utilizes the effect of interaction of multidisciplines for the optimal solution. The MDO of a turbine flow path is one of the key multidisciplinary optimization technologies in aeroengine overall design. The problem studied and presented in this paper consists in optimizing a turbine modeled by a multidisciplinary system of two coupled disciplines: turbine aerodynamics and structural strength, with temperature limited by the materials. In the present work, three modules are established to conduct the MDO research of turbine flow path: flow path design, turbine strength calculation and MDO. The aeroengine turbine flow path, including high and low pressure turbine flow path, is designed in the first module, with its efficiency estimated. In the second module, turbine rotors consisting of blades, discs and the low spool shaft are parametric modeled so as to analyze the structural aspects of turbine rotors, such as weight and stresses. MDO is conducted using multi-island genetic algorithm optimization (MIGA) optimization algorithm provided in iSIGHT software. Fully Integrated Optimization (FIO) strategy is studied to deal with the multidisciplinary analysis. The complex coupling relations between aerodynamic performance and turbine strength are analyzed to establish turbine multidisciplinary optimization system. The optimal values of loading coefficient, rotational speed, bore diameter of rotor discs defined by the shaft size, and other independent design variables are obtained in order to achieve minimum weight of turbine rotors while simultaneously meeting the strength and aerodynamics efficiency requirements. This method presented in this paper can greatly shorten turbine design cycle, improve aeroengine design ability, and is prospective to be widely applied to engineering field.