Air Volume Flow Rate and Centerline Velocity in a Tube Wind Tunnel ME 391 Instrumentation LAB # 7 Air Volume Flow Rate and Centerline Velocity in a Tube Wind Tunnel Performed: 03/05/2004 Soma : I believe I performed 50% of this lab. Sinan Ozcan: I believe I performed 50% of this lab.

Abstract The volumetric flow rate and centerline velocity of air in a tube wind tunnel were measured for a range of blower speeds. As a consistency check, the centerline speed for each flow rate was compared to the centerlines speed that would be predicted from slug and parabolic velocity profiles. The volume flow rate and centerline speed were determined by measuring the pressure signal across venturi tube and a Pitot probe. Vertical and inclined manometers were used to measure these pressure drops. The maximum volume flow rate was 0.077 + 0.002 m3/s. The measured centerline velocity was bracketed by the values predicted for slug and parabolic velocity for all blower speeds. At the lowest blower speed, the measured centerline speed is closer to the value predicted for laminar flow than it is at higher speeds. By observation we conclude that uncertainty is small when blower inlet is closed compared to the blower inlet is open.

Table 1 Atmospheric Pressure and Temperature Readings

Table 2 Measurement Readings and Calculated Values This table presents the vertical and inclined manometer readings for the gage pressure, the venturi tube, and the pitot probe, for different blower speeds. The uncertainty of each reading is also included. The calculated volume flow rate, centerline velocity and their uncertainties are also tabulated. The uncertainties from the inclined manometer are smaller than those from the vertical manometer. From the above table we can infer that Uncertainty is small when the blower inlet is closed than the blower inlet is open.

Figure 1 Measured and Predicted Centerline Velocities Versus Volume Flow Rate The measured centerline velocity is between the values predicted for slug and parabolic velocity. At the lowest blower speed, the measured centerline speed is closer to the value predicted for laminar flow than it is at higher speeds