WIND TUNNEL BLOCKAGE EFFECT AND ITS CORRECTION ON DRAG COEFFICIENT OF TWO-DIMENSIONAL BODIES

This paper deals with the applicability of Maskell's theory to porous plate and truss girder through which air stream can blow, and also to hexagonal section. The applicability was certainly proved for all sections within the range of blockage ratio studied in this test. The blockage effect is not negligible even at 5% blockage ratio. Its effect is especially large for the section which has large porous ratio. To make the correction method practical for various types of sections, the general expression of the blockage factor was attempted. From the results of this test, the generalization was successfully carried out by introducing drag coefficient defined by model outlined area in place of model projected area.