Optimization of design parameters of a pedal operated winnowing fan
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Date
2018-08
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
A pedal operated winnowing fan was developed and fabricated in the research workshop of the department of Farm Machinery and Power Engineering of G. B. Pant University especiallyfor use in hilly regions. Farmers in hilly region use conventional methods of the winnowing utilizing natural wind velocity. Available manually hand operated winnowers are heavyand the operator has to work with his one hand resulting into more effort on the arm. The present study was under taken to solve these problems. The developed winnowing fan is pedal operated where aperson can exerts more physical power for longer durations. The fan blade for this winnower is one of its vital components and was selected based on laboratory studies. During laboratory trial five sizes of fan blades having lengths of 40, 48, 60, 72, 80 cm and blade angles 10, 12, 16, 20, 22 degree, were tested at 150, 200, 230, 275, 320 and 350 rpm. The generated air velocity at the mentioned speeds was measured at 1, 2, 3, 4, 5 and 6 m positions in horizontal plane and vertical plane at 0.6 m below, 0.3 m below, at fan rotational axis, 0.3 m above and 0.6 m above with reference to position of fan centre. The results were optimized using Design Expert RSM CCD technique. Based on the optimized result obtained from the software, blade with length 48 cm, blade angle 20 degree and fan speed of 320 rpm was found most suitable for winnowing operation. In the developed prototype, physical effort using foot was transmitted to fan blades, through a pedal and connecting rod to aspur gear with 80 teeth. The spur gear further transmitted the power to smaller size of spur gear having 20 number of teeth, increasing the speed at smaller gear with 4 times. With this arrangement of speed of the winnowing fan could be achieved in the range of 320 to 360 rpm. The developed winnowing fan with three blades was tested for cleaning of wheat grain at three feed rates. The cleaning efficiency was found in the range of 68.9% to 81% while winnowing in front of the winnowing fan at a distance of 1 m.
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