59328 - Experimental characterization of losses in bladeless turbine prototype 

Multi-disk turbines, also known as Tesla turbines, are promising in the field of small-scale power generation and energy harvesting technologies due to its higher rotor efficiency and lower viscous losses. Multidisk turbine rotor has very high efficiency ( ~96%) due to the laminar flow inside the rotor which has been shown analytically in the literature. However, very low (less than 40%) overall experimental turbine efficiency has been recorded in the literature. The experimental loss models are available for traditional bladed expanders but no experimental loss characterisation is carried out on bladeless expanders till now. This article demonstrates the systematic experimental loss characterization of the 3-kW tesla expander using high speed generator. The sources of losses discussed are, in general: ventilation losses of end wall, leakage, exit loss, mechanical losses and peripheral losses.  The article begins with the discussion of these losses along with the experimental methodology of systematic evaluation of these losses. The effect these on the overall efficiency curves are presented in the subsequent sections. This experimental investigation, for the first time, gives the insight into lower performance of Tesla turbines. A separate section is devoted to the techniques which can be implemented to reduce these losses and improve the performance of the turbine.