Abstract
This paper summarises the numerical and theoretical studies of the incompressible, laminar airflow through a single flow passage of a blade-less radial turbine. Furthermore, it yields the numerical validation of the simplified theoretical model for incompressible rotor flows without the consideration of mechanical losses. It exposes the accuracy of the simplified, analytical performance prediction and flow field for a given geometry, which is based on an optimisation of performance by solving the simplified and incompressible Navier-Stokes-Equations in cylindrical coordinates. The influences of the dimensionless machine parameters on performance and efficiency are obtained from a theoretical analysis. The stream-lines of the bulk flow are derived by analytical means. The inflow conditions for maximum performance and efficiency are theoretically determined and later compared to laminar CFD. In order to quantify the error of the simplified theoretical analysis, different inflow conditions and their influences on shaft power and flow behavior are examined by means of CFD. The de-velopment of the axial velocity distribution at the inlet zone is compared to the one from the theoretical inflow assumption. The influences of Reynolds number and revolution speed on the velocity profiles are investigated. In addition to that, a compressible flow model is introduced. Numerical results are obtained and compared to the incompressible solution. More-over, compressibility effects on turbine performance are derived.
Highlights
Tesla friction turbines were invented by the famous scientistNikola Tesla [2] at the beginning of the 20th century
It exposes the accuracy of the simplified, analytical performance prediction and flow field for a given geometry, which is based on an optimisation of performance by solving the simplified and incompressible Navier-Stokes-Equations in cylindrical coordinates
In order to quantify the error of the simplified theoretical analysis, different inflow conditions and their influences on shaft power and flow behavior are examined by means of CFD
Summary
Nikola Tesla [2] at the beginning of the 20th century. They are characterised by their simple and blade-less rotor design and consist of several circular, parallel, flat disks with a central passage in the centre of rotation. Flow parameters and geometry, Tesla turbines are able to work efficiently [3]. Their main advantages are the low-cost design, robustness and competitiveness for small scale turbomachinery, which has recently been discovered by researchers [4, 5]. Pfitzner are based on the evaluation of the theoretical model for incompressible rotor flows [1] It is the mechanical design of an existing test rig, which is built for the determination of the ρ. The power coefficient is shaft power normalised with the maximum occurring power
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
