NUMERICAL STUDY FOR PERFORMANCE EVALUATION OF A CROSS-FLOW HYDRAULIC TURBINE

Abstract

Mini-hydropower plants play an important role in supplying power to remote areas. This study focuses on studying the cross-flow hydraulic turbine as an outstanding example of mini-hydraulic turbines. The study is performed using CFD analysis to assess the most appropriate design parameters that can improve the cross-flow hydraulic turbine performance. The study started with reviewing the outstanding previous studies with the aim of comparing available data to find out how to select the optimum values of the main design parameters according to previous works. The comparative study of the available data yielded a set of design parameters that are expected to constitute the optimum design parameters for a high-performance cross-flow turbine. From that study, it was found that a newly defined specific speed (named unified specific speed) can be used better to define the geometry of the radial section of the turbine irrespective of rotor width. The results of the comparative study showed that the recommended range for the unified specific speed (Ns*) is between (65) to (115), the admission arc (λ) value (90), runner diameter ratio (0.65), pitch to radial chord ratio (S/Cradial) to be (0.5), tip speed ratio (TSR) to be around (0.47) and the inlet and the outlet blade angle are 30 and 87 respectively. The nozzle outlet angle (α0) is preferred to be as small as possible and to be about 13.