Experimental evaluation of the velocity profiles and performance of a counter rotating micro-turbine by 2D laser Doppler velocimetry

The most exploited renewable energy at a global scale is hydropower, which nowadays accounts for the 18 % of the world’s electricity supply. Its production is expected to increase approximately 3.1% each year in the next 25 years maintaining its share in the mix of electricity sources. Concerning small scale hydropower, some of the current research is focusing on the limitation of the environmental impact and economical investments. The development of energy recovery systems on existing water utility networks is a new challenge for increasing the sustainability of hydroelectricity generation. The concept of the new counter rotating micro-turbine braces this goal by allowing the recovery of the energy which is spoiled in pressure reducing valves in the water supply network. The performance of the micro-turbine prototype has been evaluated through experimental campaigns involving pressure, torque, discharge measurements and 2D Laser Doppler Velocimetry (LDV). A dedicated transparent casing equipped with flat windows has been built in order to perform undistorted optical measurement and to limit the refraction and reflection of the laser beam. The velocity profiles of the axial and tangential components have been measured for several radial positions at the inlet, in the gap between the two runners and at the outlet section of the micro-turbine prototype. Numerical simulations and a further study on the mass equation applied to the investigated cross-sections of the machine have been carried out in order to complete the velocity profile where the optical access to perform LDV measurements had been blocked. These experimental methods grant a full study on the velocity profiles. The energy equation, applied to the outlet sections of both runners, allows the investigation of the flow behavior and of the related machine performance. The results back up further improvements of the runner blades shape.


Presented at:
6th IAHR International Meeting of the Workgroup on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems, Ljubljana, Slovenia, September 9-11
Year:
2015
Laboratories:




 Record created 2018-02-15, last modified 2019-08-12

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