Numerical and Experimental Analysis of Optimized Bladeless Turbines

Abstract The Tesla turbine, also known as a bladeless turbine, operates based on the principles of viscosity. These turbines are a promising alternative to expansion valves in refrigeration cycles as they recover a part of expansion work and improve the COP of the cycle. This paper presents a comprehensive numerical analysis of a bladeless turbine prototype developed by Tree Associates, utilizing Computational Fluid Dynamics (CFD) to evaluate its performance under various conditions with air as the working fluid. An unstructured meshing approach with refinement around the nozzle region was employed to capture the flow characteristics and predict turbine performance accurately. Mesh sensitivity analysis was conducted to ensure grid independence and optimize computational efficiency. Velocity triangles were analyzed to understand flow behavior and energy transfer mechanisms. The study explores the impact of nozzle shape (flat to convergent-divergent), nozzle inclination (15 to 75 degrees), and the number of nozzles (2, 4, 6 & 8) on overall turbine performance. Additionally, the effect of Mach number and shear stress are investigated. An experimental counterpart was set up and tested to validate the computational model and the results of the numerical simulations are compared with the experimental data.