Basic Research on the Evaluation of Wind Pressure in Raindrops

Abstract

For designs of ship and marine structures, wind force is an important factor. Sea disasters sometimes happen under strong wind with rain falls, however, the wind force with rain fall has some ambiguous points. In order to decrease the sea disasters, it is very important to evaluate the wind forces with rain falls correctly. Measuring the wind velocity and wind forces simultaneously in the wind tunnel with rain falls, some interesting results are obtained. They are summarized as follows : (1) When we use the wind velocity by propeller-type wind gauge, the wind force seems to be underestimated. (2) The increment ratio of drag coefficient under rain fall attains 8% to 15% when the diameter of raindrop is 1.5mm and the rain fall is 3 to 7 mm/min. The increment ratio can not be neglected. (3) The increment ratio of drag coefficient can not be explained by the increment of air dencity with raindrops.