26
the Heise gauge are recorded for each v, and each traverse position. The results are plotted as velocity profiles as shown in Figure 3-5. The velocity profiles do not reach zero at the floor because of the finite diameter in.) of the pitot-static probe.
70
60 ---- -------- -------- -------- -------- -- ----50 -------- L
E 40 -------- -------- -------41
8 3 0 --t - ------------- -------- ------------------ --- ----------10 - ------ -------- -------- --------------7 -
- - - - - - - - - - - -
0
1 2 5 6
door Tunnel profile (inches) ceiling
Figure 3-5 Velocity profiles (with uncertainty estimates) of the air tunnel for velocities increasing from 6 m/s to 66 m/s in ten steps (corresponding to motor input voltage increasing from I V to 10 V in steps I V). Table 3-1 summarizes the results of the velocity profile measurements for the air tunnel. The mean, maximum percent absolute deviation and standard deviations are tabulated outside the local boundary layer. At a particular operating condition, the maximum absolute deviation is calculated as the largest absolute magnitude of the difference between the velocity measurements and the mean value divided by the mean value. This deviation is found to reduce as the mean speed increased while the standard deviation values increased progressively.