Author(s): T Ciocan; A Stuparu; A Ruprecht; R Susan-Resiga

Linked Author(s):

Keywords: Hydrokinetic turbine; Deep river; Cavitation-free design; Blade optimization

Abstract: Hydrokinetic energy from rivers can support electricity needs with much less infrastructure than conventional hydropower, with minimum impact on free water flow. The current technology to convert kinetic energy of rivers into electricity are the hydro-kinetic turbines, and in particular for deep rivers the horizontal axis turbines which conceptually are similar to the wind turbines. We present a methodology for designing such turbines, taking advantage of the fact that the water velocity is practically constant, being dependent on the river bed slope. A specific issue addressed is avoiding the cavitation at the blade tip, when the blade is in upward position. First, a family of airfoils is represented with three modal functions determined using the Singular Value Decomposition, with the benefit of smooth and accurate interpolation. Then, the blade design includes the radial variation of pitch angle, chord length and thickness, optimized to deliver the required shaft power. The blade performance assessment first uses a steady flow for a single blade in a periodic domain. Then, a more realistic simulation of the unsteady flow for the full rotating rotor in an open surface channel is performed, particularly to check the presence of the cavitation on the blade suction side near the tip. Several design iterations are needed, including runner diameter variation, in order to meet all requirements, including the determination of the cavitation-free operation range.

DOI: https://doi.org/10.1088/1755-1315/1483/1/012010

Year: 2023