Project Summary: The fan I developed moves a huge volume of air at very high rate. The problem that I had was that the airflow would not exit out the exhaust. Instead, it would exit around the perimeter of the fan. It basically reversed it's own flow direction. I had the shroud overlapping the rear of the fan and kept the gap between the blades and the shroud very small. Still, it would blow high velocity air around the fan, not towards the exhaust. Also the prototype shroud was made of posterboard, so it started to collapse as the fan was nearing high rpm. The reverse airflow seemed to produce a vacuum in the shroud. The more rpm the more the shroud collapsed. I taped pieces of yarn to the outlet to help demonstrate flow direction. The air flow was going into the outlet.....

....I will get some more photos up as soon as I can.