Development and Performance Assessment of Conical Bladeless Turbines for Supersonic Flows

Bladeless turbines represent a promising technology for power extraction in high-speed flow environments, where conventional bladed turbines face challenges such as shock-induced losses and flow unstarting. These devices generate torque through pressure waves, namely shocks and expansions, developed along wavy-shaped walls, eliminating the need for rotating blades. This study introduces a novel conical bladeless turbine design and advances its development through Reynolds-Averaged Navier-Stokes simulations. The conical configuration is specifically designed for its simplified integration and enhanced compatibility with experimental setups compared to previous cylindrical designs. Numerical simulations are conducted at a freestream Mach number of 1.6 and 3, with a particular focus on the underlying phenomenology in order to assess the impact of design parameters on performance and feasibility for implementation at the laboratory scale. The experimental facility currently under development at the BEFAST lab, designed to validate the proposed prototypes, is also presented. A wind tunnel system is equipped for two configurations: a free-jet supersonic setup and a supersonic wind tunnel equipped with a diffuser. The latter is essential for enabling high-speed testing across a broad range of total pressures and Mach numbers. As a first design iteration, this study details the development and numerical characterization of a Mach 3-capable diffuser, for which a straight, easily manufacturable geometry is selected to ensure effective pressure recovery and stable flow conditions. This work sets the stage for upcoming experimental campaigns and presents an overall design optimized for testing and ease of manufacturing, contributing to the development of bladeless turbines for next-generation propulsion and energy conversion systems.