Design of a Micro-Turbojet Axial Turbine

This manuscript describes the design, fabrication, and test of a 75 kW single-stage turbine blisk for use in a 220 kilonewton student-built micro-turbojet. The design process includes a 1-D weighted optimization, passage geometry generation, computational fluid simulations, finite element structural validation prototyping, and final production. In the preliminary design optimization, 7 variables are used to parameterize the turbine stage. Stage performance is quantified by its efficiency, power generation, and exit swirl. One-dimensional semi-empirical loss correlations are employed to estimate inefficiency. Next, the optimized parameters are used to generate blade geometries using a model that incorporates radial equilibrium, which yields separate blade profiles across the height of the passage. In the design validation phase, Reynolds-Averaged Navier Stokes simulations are employed to validate the design and inform further iterations. Then, finite element analysis reveals structural weak points, and determines the turbine material. Finally, during manufacturing, the turbine is machined from a single solid metal disk on a 5-axis CNC mill. An aluminum prototype is made first, followed by a final production in Inconel 718, which will be integrated into the full engine assembly.