The evaluation of numerical methods for determining the efficiency of Tesla turbine operation

The Tesla turbine operation is based on the use of tangential stresses arising from the fluid viscosity and turbulence and from the phenomenon of the fluid adhesion to the surface it flows past. The paper presents a description and testing of the Tesla turbine model, pointing to the impact of the applied turbulence models on the prediction of the Tesla turbine operating conditions. Non-stationary simulations are performed using the Ansys CFX 18 commercial code. The following turbulence models are analysed: the RNG k-ε, the k-ω SST and the SST-SAS in two variants of time and space discretization. The flow field structures and the flow unsteadiness occurring in the gaps between the rotor discs are described. The distribution of power unit arising on the discs is determined and the predictions as to the power generated by the turbine coming from numerical analysis and preliminary experimental investigations are compared. A comparison of efficiency estimation is made using different methods.