Author : Sitha Khemmarath

Summary : The study was determined the optimum aspect ratio (h/D) and estimated the power output of a semi-cylindrical bladed, vertical axis wind rotor to produce power from the wind. The model testing was performed in a wind tunnel to find out the effect of two design parameters, namely: blade height and rotor diameter on the power coefficient of the wind machine. The rotors with nine values of the aspect ratios (h/D) were tested under three wind velocities to determine which rotor size would provide the best relative performance. Using the Weibull distribution function the study also analyzed the wind data for three consecutive years (1991-1993) to estimate the potential energy of the wind regime at Los Ba¤os. The theory of similitude was used to perdict size and power output of the prototypes with six different length scales (3, 4, 5, 6, 7, and 8), without constructing a large wind machine. The energy that the wind machine could harness from the wind regime was estimated by matching the power characteristic curve of the machine with the power duration curve of the wind regime in a given duration. Results of the study showed that the optimum aspect ratio (h/D) was 1.2 or when the blade height is a little longer than the rotor diameter. Decreasing or increasing the value of the aspect ratio decreased the performance characteristics of the wind machine. Estimates of the potential energy of the wind regime and the power output of the wind machines with different sizes showed that during the months of March, April, May, November, and December, the potential energy was high, with an average of 121.41 kwh/m (superscript 2)/year. The power output of the wind machine with length scales higher than 6 was predicted to meet more than 100 percent of th energy needs of a family with an average energy consumption of 5 kwh/day.