Two and Four Blades Windmill Characteristics of Traditional Salt Farmers from Demak Region

摘要

Traditional salt farmers at Demak Region of Central Java Province use wind pump for water lifting in salt production process. Simple construction and technology are main reason for the sustainability of the wind pump that consist of horisontal axis wind mill, transmission and reciprocating pump. The farmers have skill and ability to produce, maintain and operate the wind pump. This experiment study investigated the characteristics of the traditional windmill from Demak region of Central Java Province that has even number of blades. Representation of the characteristics are torque, tip speed ratio and coefficient of power. The experiment used two blades and four blades for study. The diameter of the blade was 195 cm. Shaft power output was connected to the electric generator to convert shaft power to electric power. An electric circuit with bulb lamps was used as electric controlled load. The experiment resulted that the windmill with both of the blades variation could operate up to about 250 rpm on 3.4 m/s up to 5.0 m/s wind speed. The maximum torque, tip speed ratio and coefficient of power for two blades were 1.8 Nm, 5.9 and 8.6. The maximum torque, tip speed ratio and coefficient of power for four blades were 2.0 Nm, 5.4 and 10.2.