Radial turbine

The result is less mechanical stress (and less thermal stress, in case of hot working fluids) which enables a radial turbine to be simpler, more robust, and more efficient (in a similar power range) when compared to axial turbines.

The relative pressure or enthalpy drop in the nozzle and rotor blades are determined by the degree of reaction of the stage.

The actual output at the turbine shaft is equal to the stage work minus the losses due to rotor disc and bearing friction.

The blade-to-gas speed ratio can be expressed in terms of the isentropic stage terminal velocity c0.

It consists of rings of cantilever blades projecting from two discs rotating in opposite directions.

Tesla attacked this problem by substituting a series of closely spaced disks for the blades of the rotor.

The working fluid flows between the disks and transfers its energy to the rotor by means of the boundary layer effect or adhesion and viscosity rather than by impulse or reaction.

[1] In recent decades there has been further research into bladeless turbine and development of patented designs that work with corrosive/abrasive and hard to pump material such as ethylene glycol, fly ash, blood, rocks, and even live fish.