For this purpose, two models of two and three blades were designed and fabricated from Aluminum sheet, each of them has
an aspect ratio of ( As = H/D =1), the dimension is ( H = 200 mm height and diameter D = 200 mm) and the blades were
made of semi – cylindrical half of diameter (d = 100 mm). The two models were assembled to have (overlap e = 0 and a
separation gap e' = 0