A Test Rig for the Investigation of the Performance and Flow Field of Tesla Friction Turbines

The paper summarizes the development and optimization of a flexible test facility for 3D tomographic PIV/PTV measurements of the flow field in the rotor gap of a Tesla friction turbine and performance evaluations. The main aim of the experiment will be the validation of CFD simulations. Another intention is to gain a deeper understanding of the flow phenomena in the gap. The extension of existing theoretical investigations lead to an improved knowledge of dimensioning such bladeless turbines with the goal of maximum power and efficiency. The mechanical design of the rotor, based on these equations, was optimized for a minimal deformation and low mechanical stress. Modal and harmonic response analyses due to imbalance forces have been performed to ensure low vibrations during operation. The design of the feed and guide vanes have been optimized for uniformity of the flow entering the Tesla disk’s gap. The rotor outlet is optimized to achieve minimal pressure loss at the intended exit swirl angle. For the demonstration of the measurement technique preliminary tomographic PIV/PTV tests have been carried out. The measurement, safety monitoring and feedback-control software was developed for running on a National Instruments compact RIO real-time target.