Abstract

The Tesla turbine operates on viscous shear between parallel discs and, despite its mechanical simplicity, is typically characterized by low efficiency. In the present study, three-dimensional computational fluid dynamics (CFD) simulations performed using ANSYS Fluent are used to examine a hybrid Tesla turbine design in which 0.25 mm thick partial height blades are fitted on the disc faces, with 1 mm distance between them, thereby creating a 0.5 mm flow passage. Simulations employing the k-ω Shear Stress Transport (SST) turbulence model were performed for three blade counts (3, 6, and 9) and three blade geometries (curved, straight, and inverted curve) at rotational speeds from 1000 to 19,000 rpm and inlet pressures of 2 to 4 bar. Comparative analyses with standard 1 mm plane-disc rotors and reduced-gap 0.5 mm plane-disc rotors show that the hybrid arrangement consistently provides better torque and efficiency; this enhancement is not only due to the reduced gap but also to increased pressure-induced momentum and improved flow guidance provided by the blades. The curved blade was found to be the most favourable configuration, and the efficiency was positively related to the number of blades, with a maximum efficiency of 57.5% at 13,000 rpm using nine blades. The analyses sustain the conclusion that adding blades to the rotor discs positions the Tesla turbine model as a hybrid apparatus, combining viscous and pressure mechanisms to significantly enhance turbine performance.

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