• Created by user-ccbc7, last modified by user-47305 on Oct 17, 2010

Experiment 2: February 28, 2010

Setup

This experiment consisted of one 10' Manifold with 1 in. holes drilled every 5 cm on one side of the pipe. This resulted in an Am/Avc = 1.

Results & Discussion

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Figure 1: 10' Manifold Results compared with theoretical expectations

The results of our second experiment seem to reaffirm the results that we found in the first experiment, despite the problems with data collection that existed in the first experiment. The flow starts low then peaks in the first quarter of our manifold and then gradually decreases after that. And as showed in the graph, this is completely opposite what the theory of pressure recovery predicts.

The good news with these results is that the flow from the ports might be sufficiently uniform for it to work in the AguaClara plants. The mean velocity is 0.214 m/s and has a standard deviation of 0.021 m/s, which might be low enough variation for the AguaClara plants. The mean velocity might be a little high when considering the restriction of floc breakup prevention as there is an average energy dissipation rate of 19 mW/kg when the max allowable to maintain flocs is 10 mW/kg. This was determined by using the equation .

We estimated the flow rate being provided by the pump to be 3.8 L/s. This value was calculated using the following equation:

This finds the average port flow of the measured ports and then multiplies it by the total number of ports. Given this flow rate, the velocity inside the manifold would be 0.21 m/s at the beginning of the manifold. This meets the specification of = 0.15 m/s but the velocity would decrease throughout the manifold. However, after considering the fact that the manifold is oriented with the ports pointed downwards in the sedimentation tank, we have realized that scour velocity is not as big of an issue in our manifold as we thought.

We still do not understand the fluid mechanics of what is happening in the manifold and need to investigate that further. We plan on doing this by pushing the boundary of the ratio Am/Avc. Theory says that the smaller that ratio gets, the more pressure recovery should dominate and the higher velocity should be at the end of the manifold compared with the beginning of the manifold as illustrated in Figure 1 on the main page.

To see the calculations for the experiment, use the MathCad Calculations and the Excel Calculations.

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