Experiment 4: May 6, 2010
Setup
This experiment consisted of one 10' Manifold with 1 in. holes drilled every 5 cm on BOTH sides of the pipe. This resulted in an Am/Avenacontracta = 0.5. This ratio was already tested with the 20' Manifold setup, but we were interested to see if the length of the manifold played a role in the flow distribution or if the results for this experiment would be proportional to that of the 20' Manifold setup.
Procedure
The procedure for this test was the same as the procedure for experiment 2. A sample size was chosen (1 in every 5 ports). The Acoustic Doppler Velocimeter (ADV) was then positioned approximately 17 cm from the port being measured. We had attempted to position the ADV closer to the manifold to get a more accurate reading, but we were getting poor readings and thought this might be due to interference of the sonar waves by the PVC pipe. The ADV would be positioned on the edge of this port. Thirty seconds to a minute of data would be recorded, and then it would be shifted to the other side of the port by a centimeter. This process would be repeated until it was ascertained that the ADV had moved out of the range of the port jet (signified by a velocity of, or close to 0 m/s).
This was repeated on each port that was decided to be part of the sample size.
Results
Figure 1 shows the results from the experiment. The red line indicates the theoretical velocity profile if the effects of pressure recovery were included. The green line indicates the theoretical velocity profile if the effects of pressure recovery were not included. The boxes are data points that represent running averages for each port. The white boxes mean to signify that these ports were outliers (they were not statistically significant).
Unknown macro: {float}
Figure 1
Conclusion
Looking at the data points, it seems as if there was a lot of noise. Taken as a whole, the results show no discernible trend. However, if the outliers are eliminated and only the the blue boxes are regarded, then a trend emerges. It looks as if the velocity in the ports acts like pressure recovery does not play a big role. This is interesting and justifies the conclusions we made from experiments 1 and 2.