Science Buddies: "Ask an Expert"

I have been building a wind tunnel for several days consisting of a cardboard rectangular prism, 3,000 rpm LL140 fan, and a smoke machine. I am trying to get a steady stream of smoke that I can pass over objects and I have yet to accomplish this despite adding a grid of rolled up paper to improve laminar flow. What should I do to achieve this?

Jasas004 - I think you were on the right track with the addition of a grid to improve laminar flow. Likely the fan blowing the smoke that was introduced was very turbulent and mixed the smoke and air. In wind tunnel photos I've seen, a small nozzle introduced a small diameter flow of smoke over an auto body or wing chord. Perhaps a small tube and nozzle could provide the smoke and you could move it around your objects and observe the airflow effect.

Rick Marz