[8D] "In wind tunnel testing, by what factor is the wind speed reduced by?"

Back in 1957 to 1959 I was personally involved in the design of the nozzle control for the wind tunnel at the Arnold Research center in Tullahoma, TN. (the nozzle control was designed at Rochester, NY by General Dynamics Electronics). The nozzle itself was 120 feet long, and built by the Electric Boat Division of G.D. The steel walls of the nozzle were warped by the nozzle control system to produce various venturi configurations as needed. The input air to the nozzle was supplied by HUGE electric motors (GE) fitted with propellors. The venturi effect in the nozzle accelerated the airflow to as much as 600mph. An interesting side effect of the acceleration of the air is that the temperature of the air drops dramatically as it passes through the venturi tube. This is the old rule of conservation of energy. The increase in velocity is paid for with a drop in temperature. This is my kind of long way to say that the wind speed is is not neccessarily reduced in wind tunnel testing.
Puff