h1. Experiment 1: February 25, 2010
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!ManifoldStraight.png|width=350px!
Manifold running parallel to flume walls and bed
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h2. Procedure
The manifold we designed is a 10' long, 6" PVC pipe with 1" diameter holes drilled every 5cm. The manifold had water pumped through it at a rate of 3.8 L/sec (roughly 1 gallon/min) and the water flows through a whole 10' section of 6" PVC pipe before it gets to the manifold to ensure that the effects of the pump have dissipated in the pipe. The manifold is suspended 14" above the bed of the flume by U-clamps and the manifold is spaced 7" from the flume wall to make sure that it runs parallel to the flume bed and wall. We double checked this by measuring the distance from the flume wall and flume bed both at the beginning of the manifold and at the end of the manifold. The ports of the manifold are positioned so that the jets exiting from them run parallel to the bottom of the tank.
The [Acoustic Doppler Velocimeter| Acoustic Doppler Velocimeter] (ADV) used to take velocity readings was mounted to a beam running across the width of the flume. The ADV was positioned so that it was aimed head on into the ports (so it also lies parallel to the bed of the flume) at a fixed distance of 17 cm from the port openings.
+(Acronyms like ADV should be spelled out at least once in your document. How does ADV work? What software was required? Can you provide a brief procedure with screen shots for how someone would use the software in the future?)+10' Manifold with a Am/Ap = 1
h2. Procedure
The measurements were taken at 4 different points along the manifold, separated into at close to fourths as possible given the interference of bolts protruding from the walls of the flume. For each port, we maneuvered the ADV in front of each port until we thought we were in the the peak portion of the flow. We recorded data for 1 minute and then moved the ADV 1 cm to the left and 1 cm to the right of our first recording point to ensure that we captured the peak flow. We collected data at these points for 1 minute also.
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!VelocityProfilePort52.png!
Example graph of a velocity profile acrossfor one of the ports
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In the analysis of our data, we took the mean of the velocities at each port for all 3 (and sometimes 4) measurements. Then we plotted the velocity profile for each port, assuming a Gaussian profile, and estimated the maximum flow rate at each port. These calculations were thanthen plotted along the length of the manifold to give a velocity profile for the uniform manifold setup.
h2. Results & Discussion
After collecting the data the way we did, we realized that there were many flaws in our procedure. First off, any 3 points can be fit to make a Gaussian curve so there was no real way to determine that we were at the peak flow for each port so we ran this experiment again with more accurate data collection techniques. For those results, check out [Experiment 2| Inlet Manifold-10ft Manifold Test 2]. The results of this experiment are still displayed and discussed because they aren't necessarily bad, they just have the potential to be bad.
The results of our first experiment for a uniform manifold were not what we expected. Due to the expectation of pressure recovery dominating major losses (friction inside the manifold) we had expected the velocity coming out of the ports to actually increase along the length of the manifold. However, once the maximum velocity for each port was plotted against its distance down the manifold (see graph) it seemed that just the opposite trend was true. The velocity appeared to have peaked early on in the manifold and then gradually decreased after that.
!Experiment1.png!
We reasoned that some sort of headloss must be dominate over pressure recovery, but after discussion with Monroe, we determined that our procedure did not give us the most accurate data and we would need to make changes (see Experiment 2). We also realized that we wanted to get more data points along the manifold in order to see if the trend we got with our first set of data was accurate.
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