Introduction
It is key to know the true flow rate from our pump for our understanding of how our experimental model can be related to a true application of an inlet manifold in an AguaClara plant. In order to evaluate the flow rate inside our manifold, the experimental set up was modified so that the Acoustic Doppler Velocimeter (ADV) could be utilized. Two pumping models were evaluated, one where the pump was directly attached to the manifold and the other where it was not connected to the manifold, this is the vacuum pump setup used to increase the flow rate.
Set up
The pump was positioned at the end of the 10-ft long PVC pipe. The ADV was positioned 17 inches away from the end of the pump. Figure 1 shows the ADV positioning. Figure 2 shows the first pump set up (connected). Figure 3 shows the second pump set up. The 10-ft PVC was used so that the flow would be fully developed at the point at which measurements were taken.
NEED PICS FROM NICO IN THE LAB
Figure 1
Figure 2
Figure 3
Procedure
The procedure is identical for the two experimental models. The ADV was positioned at the top of the pipe. A 30 second velocity measurement was taken here. The ADV was then repositioned to be 1 cm lower than the previous location, and a 30 second velocity measurement was taken. The procedure was repeated until we got to the bottom of the pump.
Results and discussion
The results for the first experiment (with the pump directly connected to the manifold) can be seen below in figure 4.
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Figure 4: Measured flow rate for the experimental model where the pump is connected to the manifold.
You can see that the velocity has a unique, unexpected profile in this set up. There are two positive peaks and one large negative peak while the rest of the profile remains essentially zero. The reason for this is hypothesized to be due to the fact that the connected pump actually physically moves the PVC pipe back and forth. This would contribute to the negative velocity measured at 5.5 inches.
The results for the second experimental model (vacuum) can be seen below in figure 5.
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Figure 5: Measured flo rate for the experimental model where the pump is not connected to the manifold.
Here you can see that the velocity follows a more standard profile. There is a distinct peak and a relatively symmetrical pattern. By summing the velocities, we estimated the velocity to be 3.4 L/s. This is lower than the expected 6.7 L/s for the vacuum pump set up, but it is what we were able to derive using the data we collected.
The velocity was calculated by estimating the center of the flow and solving for the flow rates of the concentric rings where measurements were taken.
Conclusions
From analyzing the set up where the pump is actually connected to the pipe, we can see that the velocity is not reliable. This may change if the manifold has more mass or is better stabilized. However, as it stands, the connected pump can likely not be reliably used to measure flow rates. The vacuum pump, however, shows a good velocity profile and a corresponding flow rate of ___. This flow rate is what the pump advertised, and is what we assumed in our theoretical analysis of the inlet manifold. This helps to make the conclusions drawn from other experiments more reliable.