Weight Reduction of Agricultural Propeller Fans (Part 2)
Simplified Calculating Method for Blade Strength
1994 Volume 56 Issue 5 Pages 65-72
Details
1994 Volume 56 Issue 5 Pages 65-72
In this study, a commercial frost control fan was chosen as one of the propeller fans for agricultural use utilized in open space, and a calculating method for blade design of fan was proposed. Drag and lift affecting on the blade were divided into two component forces acting along the rotating axial direction and the tangential one. The former force was estimated by measuring the air flow velocity in front and behind of fan, and the latter force was determined by measuring the driving torque of fan. Both forces were finally applied to the blade in the form of bending moment. Strength was calculated based on the mechanical model of blade consisting of rectangular plate under the action of bending moment in two vertical directions and centrifugal force in one direction of plate. It was clarified from the result that the commercial fan tested had more structural strength than the required one. The proposed fan with 2.0mm thickness of blade showed almost the same blow performance as the commercial one with 2.5mm thickness of blade.
