Design and Computational Study of Supersonic Turbines for Rocket Engines

The optimization of supersonic turbines is a rapidly evolving field of research whose main objectives are improving the performance of the turbine and increasing the life of the machine. Achieving these goals becomes even more challenging when high-energy working fluids are used, as in the rocket industry. This project focuses on the aerodynamic design and numerical analysis of supersonic turbines, encompassing turbine mean-line design, design of vane and blade profiles, culminating in computational fluid dynamics simulations of the blade passages. The project aims at investigating the impact of design parameters on the flow structure of supersonic turbines, as well as on the reliability of isolated stator calculations -very widespread for stator shape optimization- compared to coupled stator-rotor calculations. Therefore, particular attention is given to the fluid-dynamic phenomena occurring at the stator outlet and their interaction with the rotor leading edge. To accomplish these objectives, three turbine stages with different expansion ratios are designed from scratch. The design process is based on non-dimensional parameters, including the flow coefficient, loading coefficient and degree of reaction, leveraging an in-house mean line design code. Design maps are then generated for the three cases to identify the optimal design points. Subsequently, inverse design methods implemented in in-house codes based on the method of characteristics are used to compute the shape of vane and blade passages. Finally, CFD simulations are performed using the SU2 software. The analysis begins with isolated stator calculations, followed by coupled stator-rotor calculations, employing different numerical approaches to examine the flow field within the blade passages. Attention is paid to the mesh resolution to enable the analysis of the shock structure and development of the boundary layer. The findings of this study contribute to a deeper understanding of supersonic turbine fluid dynamics and offer potential improvements in the design of high-performance turbomachinery, particularly for aerospace and energy applications.