I am designing a wind tunnel for my final year project. Im am now a little lost at the power requirements area. To select a fan, i understand that i have to overcome the pressure drops through out the tunnel by choosing a fan that has a higher pressure rise. So far i have figured out that i have to calculate individual pressure losses through out the various sections of the tunnel and the total loss should be the sum of the individual section losses. And therefore the power required should be pressure loss x flow rate. Now what i want to know is, is that really the total power required? Dont i have to be bothered about the power required to maintain the flow if there were no losses? (ie, Power = actual power required + power required to over come losses) My wind tunnel has a 12"x12" test section and i am designing it for a 25m/s wind speed. Could someone assist me regarding this? Also im a mechanical engineering student and a aviation is a new field to me.