The efficiency of a wind tunnel

Miller, Wm H (Massachusetts Institute of Technology)
February 1922

If, by some means, a steady state of motion of a perfect fluid were established in an ideal wind tunnel, there would be no losses, and the motion would persist indefinitely. In the actual tunnel, the function of the motor-fan group is overcome by the total loss of head in the tube due to friction and eddies.

An Adobe Acrobat (PDF) file of the entire report: