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The
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information
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on
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this
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page
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pertains
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to
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the
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research
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performed
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by
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the
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Spring
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2010
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Inlet
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Manifold
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team.
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See
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...
...
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for
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the
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most
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up-to-date
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research.
Objectives
The objectives of this research team are to experimentally test the inlet manifold recreating the same conditions that will face in a real AguaClara plant, and modify the design based on the results.
To begin with, we calculated the manifold dimensions which include:
- Pipe diameter
- Ports' diameter
- Ports' spacing
The calculations for this experiment were based on the Agalteca design flow and tank dimensions.
Based on the Manifold Theory, the initial idea is to prove that to create an evenly distributed flow throughout the different ports of the manifold, we would have to taper the pipe to have the same velocity along the manifold and therefore the same flow in each port.
To begin with the study, the idea is to prove that a constant diameter manifold would fail to deliver an evenly distrubuted flow along the ports. Therefore we should calculate a manifold with a constant diameter for the design flow and the desired velocity which should be higher than 0.15 m/s (minimum scour velocity). To calculate the manifold diameter we use the following equation and round diameter to a commercial drill size:
| Latex |
|---|
h2. Objectives The objectives of this research team are to experimentally test the inlet manifold recreating the same conditions that will face in a real AguaClara plant, and modify the design based on the results. To begin with, we calculated the manifold dimensions which include: * Pipe diameter * Ports' diameter * Ports' spacing The calculations for this experiment were based on the Agalteca design flow and tank dimensions. Based on the Manifold Theory, the initial idea is to prove that to create an evenly distributed flow throughout the different ports of the manifold, we would have to taper the pipe to have the same velocity along the manifold and therefore the same flow in each port. To begin with the study, the idea is to prove that a constant diameter manifold would fail to deliver an evenly distrubuted flow along the ports. Therefore we should calculate a manifold with a constant diameter for the design flow and the desired velocity which should be higher than 0.15 m/s (minimum scour velocity). To calculate the manifold diameter we use the following equation and round diameter to a commercial drill size: {latex} $$ D_{SedManifold} = \sqrt {{{4*QSedManifold} \over {V_{Scour} *\pi }}} $$ {latex} |
With
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the
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rounded
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Diameter,
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we
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calculated
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the
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real
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velocity
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inside
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the
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manifold
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using
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the
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following
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equation:
| Latex |
|---|
} $$ V_{SedManifoldMax} = {{4*Q_{SedManifold} } \over {D_{SedManifold} ^2 *\pi }} $$ {latex} |
Now
...
by
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changing
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the
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distance
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between
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ports
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(
| Latex |
|---|
}$$ B_{SedManifoldOrifice} $$ {latex} |
)
...
and
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we
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can
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calculate
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the
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amount
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of
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ports
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(
| Latex |
|---|
}$$ N_{SedManifoldOrifice} $$ {latex} |
)
...
needed,
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different
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ports'
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diameters
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(
| Latex |
|---|
}$$ D_{SedManifoldOrifice} $$ {latex} |
)
...
and
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also
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energy
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dissipation
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rates
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(
| Latex |
|---|
}$$ \varepsilon _{\max } $$ {latex} |
)
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through
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those
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ports,
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by
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using
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the
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following
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equations:
| Latex |
|---|
} $$ N_{SedManifoldOrifice} = floor\left( {{{L_{SedManifold} } \over {B_{SedManifoldOrifice} }}} \right) $$ {latex} |
Number
...
of
...
ports
...
we
...
can
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calculate
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the
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flow
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per
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port
| Latex |
|---|
} $$ Q_{SedManifoldOrifice} = {{Q_{SedManifold} } \over {N_{SedManifoldOrifice} }} $$ {latex} |
Once
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we
...
calculated
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the
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flow
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we
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can
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calculate
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the
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port's
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area
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and
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diameter
| Latex |
|---|
} $$ A_{SedManifoldOrifice} = {{Q_{SedManifoldOrifice} } \over {Pi_{VenacontractaOrifice} *V_{SedManifoldMax} }} $$ { |
| Latex |
|---|
} {latex} $$ D_{SedManifoldOrifice} = {{2*\sqrt {A_{SedManifoldOrifice} } } \over {\sqrt \pi }} $$ {latex} |
Finally
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the
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energy
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dissipation
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rate
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should
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be
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checked
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to
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ensure
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that
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the
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flocs
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will
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not
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break
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while
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entering
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the
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Sedimentation
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Tank.
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These
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two
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equations
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are
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equivalents.
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The
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first
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equation
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was
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derived
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from
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Monroe
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and
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the
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second
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one
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was
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provided
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by
...
him
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also
...
from
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external
...
bibliography.
| Latex |
|---|
} $$ \varepsilon _{\max } = {{\left( {0.34*V_{Jet} } \right)^3 } \over {D_{Jet} }} $$ { |
| Latex |
|---|
} {latex} $$ \varepsilon _{\max } = {1 \over {20*D_{SedManifoldOrifice} }}\left( {V_{SedManifoldMax} } \right)^3 $$ {latex} |
The
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results
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of
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those
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calculation
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proposed
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a
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6"
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PVC
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pipe
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with
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1"
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ports
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spaced
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5
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cm
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center
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to
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center
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(total
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57
...
ports).
...
...
...
These calculations assumed that the sum of the areas of the vena contracta of the ports should equal the cross sectional area of the pipe. The justification of this assumption is based on the following graph, where we can see how the flow distribution varies along the manifold, as the ratio of the manifold cross sectional area and the sum of the areas of the vena contracta of the ports (from now on expressed as Am/Avc ratio) varies.
Figure 2: Am/Avc ratio graph
By looking at this graph, it is clear that the best flow distribution would be having an Am/Avc ratio of 3. There are two ways to have this relationship and these are:
- Have a very large diameter manifold
- Have very small ports' diameteres
Both these solutions will create unwanted scenarios.
- The velocities inside the manifold will be too slow. Possible sludge settling inside the manifold. Also the idea is to make this design adequate for larger plant flows, with the consequence of having too large of a pipe inside the sedimentation tank which is not desirable.
- The energy dissipation rate of the flow coming out of the ports will be too high leading to potential floc breakup.
Based on these the next best flow distribution is when the Am/Avc ratio is 1 and in these case we daon't have the unwanted scenarios just described so it is reasonable to proceed with this Am/Avc ratio.
The next step is to recreate in the lab the conditions of that manifold in the Agalteca plant. To do this, a submersible pump with the design flow will recreate the inlet flow and the whole manifold replica, will be installed in a flume to begin the flow testing.
The of the ports will be measured using an ADV as shown in the following image.
The results obtained by this measurements will be plotted and compared to the theoretical expected values.
Based on the obtained results, the manifold should be modified and the testing procedure should be repeated until even flow distribution is achieved.
Experimental Methods and Results
Setup and Procedure
| Wiki Markup |
|---|
|Pictures] These [calculations|Inlet Manifold Research and PIV measurements^Agalteca Manifold Design 1.xmcd] assumed that the sum of the areas of the vena contracta of the ports should equal the cross sectional area of the pipe. The justification of this assumption is based on the following graph, where we can see how the flow distribution varies along the manifold, as the ratio of the manifold cross sectional area and the sum of the areas of the vena contracta of the ports (from now on expressed as Am/Avc ratio) varies. !Area Ratio Graph.jpg! h5. Figure 2: Am/Avc ratio graph By looking at this graph, it is clear that the best flow distribution would be having an Am/Avc ratio of 3. There are two ways to have this relationship and these are: # Have a very large diameter manifold # Have very small ports' diameteres Both these solutions will create unwanted scenarios. # The velocities inside the manifold will be too slow. Possible sludge settling inside the manifold. Also the idea is to make this design adequate for larger plant flows, with the consequence of having too large of a pipe inside the sedimentation tank which is not desirable. # The energy dissipation rate of the flow coming out of the ports will be too high leading to potential floc breakup. Based on these the next best flow distribution is when the Am/Avc ratio is 1 and in these case we daon't have the unwanted scenarios just described so it is reasonable to proceed with this Am/Avc ratio. The next step is to recreate in the lab the conditions of that manifold in the Agalteca plant. To do this, a submersible pump with the design flow will recreate the inlet flow and the whole manifold replica, will be installed in a flume to begin the flow testing. The of the ports will be measured using an ADV as shown in the following [image|https://confluence.cornell.edu/download/attachments/118477658/SL741267.JPG]. The results obtained by this measurements will be plotted and compared to the theoretical expected values. Based on the obtained results, the manifold should be modified and the testing procedure should be repeated until even flow distribution is achieved. h2. Experimental Methods and Results h4. Setup and Procedure {float} !ManifoldStraight.png|width=320px! h5. Figure 3: Manifold running parallel to the flume wall and bed {float} |
The
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manifold
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we
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designed
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is
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a
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10'
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long,
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6"
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PVC
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pipe
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with
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1"
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diameter
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holes
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drilled
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every
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5cm.
...
The
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manifold
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had
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water
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pumped
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through
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it
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at
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a
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rate
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of
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3.8
...
L/sec
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(roughly
...
1
...
gallon/min)
...
and
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the
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water
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flows
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through
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a
...
whole
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10'
...
section
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of
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6"
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PVC
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pipe
...
before
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it
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gets
...
to
...
the
...
manifold
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to
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ensure
...
that
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the
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effects
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of
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the
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pump
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have
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dissipated
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in
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the
...
pipe.
...
The
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manifold
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is
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suspended
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14"
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above
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the
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bed
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of
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the
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flume
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by
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U-clamps
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and
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the
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manifold
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is
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spaced
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7"
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from
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the
...
flume
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wall
...
to
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make
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sure
...
that
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it
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runs
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parallel
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to
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the
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flume
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bed
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and
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wall.
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We
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double
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checked
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this
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by
...
measuring
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the
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distance
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from
...
the
...
flume
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wall
...
and
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flume
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bed
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both
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at
...
the
...
beginning
...
of
...
the
...
manifold
...
and
...
at
...
the
...
end
...
of
...
the
...
manifold.
...
The
...
ports
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of
...
the
...
manifold
...
are
...
positioned
...
so
...
that
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the
...
jets
...
exiting
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from
...
them
...
run
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parallel
...
to
...
the
...
bottom
...
of
...
the
...
tank.
...
The
...
...
...
...
(ADV)
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used
...
to
...
take
...
velocity
...
readings
...
was
...
mounted
...
to
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a
...
beam
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running
...
across
...
the
...
width
...
of
...
the
...
flume.
...
The
...
ADV
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was
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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.
| Wiki Markup |
|---|
{float} !ExampleVelocityProfile.png|width=400px,align=center!\\ h5. Figure 4: Example of a velocity profile of one of the ports {float} |
The
...
measurements
...
were
...
taken
...
every
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5-6
...
ports,
...
which
...
gave
...
us
...
10
...
different
...
data
...
points
...
along
...
the
...
manifold.
...
For
...
each
...
port,
...
we
...
maneuvered
...
the
...
ADV
...
to
...
the
...
edge
...
of
...
the
...
port
...
hole.
...
We
...
then
...
took
...
measurements
...
as
...
we
...
moved
...
the
...
ADV
...
across
...
the
...
port
...
in
...
steps
...
of
...
0.5cm.
...
We
...
recorded
...
data
...
for
...
approximately
...
1
...
minute
...
and
...
then
...
moved
...
the
...
ADV
...
0.5cm
...
further
...
and
...
measured
...
again
...
until
...
we
...
were
...
sure
...
we
...
had
...
captured
...
the
...
entire
...
jet
...
profile.
...
In
...
the
...
analysis
...
of
...
our
...
data,
...
we
...
took
...
the
...
mean
...
of
...
the
...
velocities
...
at
...
each
...
port.
...
Then
...
we
...
plotted
...
the
...
velocity
...
profile
...
for
...
each
...
port
...
and
...
estimated
...
the
...
maximum
...
flow
...
rate
...
at
...
each
...
port.
...
These
...
calculations
...
were
...
then
...
plotted
...
along
...
the
...
length
...
of
...
the
...
manifold
...
to
...
give
...
a
...
velocity
...
profile
...
for
...
the
...
each
...
manifold
...
setup.
...
Results
...
...
...
...
...
...
...
...
...
...
...
2
Experiment 3: 20' Uniform Manifold Am/Avc=0.5
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...
...
...
...
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...
...
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