Table 3-1 Air tunnel velocity characteristics

    Mean          % Maximum         % Standard deviation
velocity (m/s) absolute deviation  (with respect to mean)
     6.1              2.17                  0.98

     12.4             0.76                  0.32

     19.0             0.70                  0.31

     25.7             1.19                  0.47

     32.4             0.82                  0.34

     38.9             0.75                  0.39

     45.4             0.80                  0.42

     51.7             0.75                  0.35

     58.0             0.91                  0.33

     64.2             0.70                  0.28


                       Velocity Profiles of the Water Tunnel

Experimental Set-up

    The experimental set-up used here is similar to that of the air measurements except that a free air-water surface is maintained in this case. The pitot-static probe is inserted from the slot in the ceiling of the test section at a distance of 10 in. from the start of the test section. The tubes from the probe are connected to the transducer after flooding all parts with water. Visual inspection insured no bubbles were present. The pitot-static probe is connected to Validyne P55D pressure transducer that has a full-scale range ±2.5 in. of H20. The output of this transducer is connected to the HP 34970A DAQ unit. The 3D traverse with servomotors is used to position the probe. An NI PC16024E series data acquisition card with programmable voltage output is used for controlling the frequency of the water pump, thereby controlling the speed of the water tunnel. An integrated