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Sedimentation tank exit channel
Josiah, Taisuk, Jeff
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The sedimentation tank exit channel is currently a replicate of the entrance channel. The entrance channel size is based on the constraint of not breaking up flocs. This constraint causes the exit channel to be much larger than is necessary. The exit channel should be designed based on the constraint that the head loss in the open channel must be very small compared with the head loss in the launder orifices. This constraint ensures that the flow is uniformly distributed between sedimentation tank bays. The most sophisticated solution algorithm could use the direct step method and incorporate the changing flow through the channel. A simpler solution that would be conservative would be a simple friction slope calculation using the Darcy Weisbach equation adopted for flow in a rectangular channel. The friction slope times the length of the channel can be compared with the head loss in the orifices.
Completed 6/24. Assumed the head loss in the channel was 20 times smaller than the head loss in the launder, which we then converted into a ratio of the flow of the sedimentation tanks (added variable PI.QSedTanks to naming guide). The code assumes the channel is square and starts with the width equal to the inlet channel width, then iterates to find the smallest width that fulfills the head loss requirement. The larger of either a W.ExitChannelMin or the returned value from the iteration is returned. A W.ExitChannelMin is needed to ensure that the tank is large enough for a person to put their hand in the channel to cap the launders. We assumed this minimum width to be .0254 m (10"). Need to add W.ExitChannelMin to Variable Naming Guide and need to document the code. A derivation of PI.QSedTanks from the head loss equation written in MathType was included in the documentation.
Floc Hopper design
Ben, Chris ~ Est. Completion Date 6/30
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