Improvement of Vertical Savonius Wind Turbine Performance

Abstract

This work presents a study of the vertical Savonuis wind rotor, including design,construct, and test, with a new configuration parameters, to improve its performance.The new rotor's parameters consist of two stages-four blades (main andsecondary). The blades are arranged such that, leaving a separation gap between theinner ends of the blade to get the benefit of the air flow reaction energy in the bucketon the exit side, The secondary stage height equals 1/4 of the rotor height. The bladesof the second stages are shifted by 45 degrees from main stage on the same axes.It is expected that the secondary stage assists the starting of the rotor and preventsthe counter torque to appear in the static and dynamic torque cycle.This Savonius rotor turbine was tested on the subsonic wind tunnel model AF100made by TecQuipment Ltd., with the range of wind velocities (U=0 to 20 m/s), on noload, it is found that the rotor started rotation at wind velocity of 1.2 m/s. The test ofstatic torque Ts was done under constant velocity of 12 m/s, and dynamic torque Twas performed under air velocities of (U=10, 12, 14, 16, and 18 m/s).Testing results show that the Savonius rotor turbine can start at low wind velocityfrom any position. The static torque coefficient Cts was improved, with peak to peakvalue of (17.2 – 39) % in the positive range during cycle of α=180º. The maximumpower coefficient approach to (Cp=16% at λ= 0.8). Comparing the performance ofthis turbine with the others show that the power and torque coefficients are improved.