Yes, you'll have to find a way to convert the voltage output reading from the personal fan anemometer into airspeed. There are many creative ways of doing this, and it takes a little scientific thought. Do you have any ideas of how to do it? You mentioned an equation, but the relationship between wind speed and voltage is going to be defined by your specific tunnel setup, so you will most likely need to create a function of conversion yourself by taking multiple data points at multiple different known airspeeds (perhaps using another anemometer, to match the voltage reading with the second one's airspeed reading).
Does that make sense?
O God, Thy sea is so great, and my boat is so small!