Experimental Measurements of Bladeless Turbine Power Extraction

This paper outlines the design, fabrication and testing of a Mach 3 nozzle with integrated conincal bladeless turbine. The nozzle was designed using an axisymmetric method of characteristics (MOC) design tool, aiming to accelerate flow from subsonic to Mach 3, without the presence of shock waves, which would hinder the uniformity of the flow at the nozzle exit. To facilitate low-pressure startability, a cylindrical diffuser was installed at the exit of the nozzle. CFD simulations of the nozzle and diffuser were performed, showing full startability at stagnation pressures above 4 bar, demonstrating the diffuser's ability to recover pressure. Following the computational simulations, an experimental campaign was performed with the goal of replicating the numerical study. The results of the experimental campaign showed good agreement with the numerical results, confirming full starting of the nozzle at stagnation pressures above 4 bar. Following this, numerical simulations were performed on a conical bladeless turbine exposed to Mach 3 flow. A sweep of rotational speeds was used to derive a performance map of the turbine, which yielded a power output of up to 78 W at 7000 rad/s for the 4.25 bar case. Static torque tests were performed at various stagnation pressures, resulting in 0.012 Nm, 0.017 Nm, and 0.018 Nm of torque production at 4.1, 5.0, 6.0 bar respectively.