Experiment 3: March 3, 2010

Setup

This experiment consisted of two 10' Manifolds, connected by a rubber coupling to create one 20' Manifold. The 20' Manifold had 1 in. holes drilled every 5 cm on one side of the pipe. This resulted in an Am/Avc = 0.5 because the Manifolds cross-sectional area stayed the same but the number of ports doubled. Due to the increase in the manifold size, we reconfigured the pump to be working as a vacuum pump so that we could achieve higher, more readable flow rates, in the ports. The estimated flow rate of this pump set up is approximately 6.7 L/s.

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. 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 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).

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. The velocity in the ports acts like pressure recovery does not play a big role. This is interesting and matches our results from experiments 1 and 2.

This experiment was run at a higher flow rate than what we would typically see in AguaClara plants. The flow rate was estimated by calculating the average port flow rate and then multiplying by the total number of ports. The actual equation used follows:

For this experimental setup with the vacuum pump we estimated a flow of 6.7 L/s. The energy dissipation rate was calculated by using the following equation: . The average energy dissipation rate was found to be 66 mW/kg and the maximum energy dissipation rate rises to 129 mW/kg, these values greatly exceed the 10 mW/kg standard of AguaClara plants. But this manifold was also running at a flow rate of 6.7 L/s and AguaClara plants would not operate under these conditions. This experiment was solely about testing the limits of the Am/Avc ratio.

Here are the Manifold calculations.