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The LFOM mimics the Sutro weir with a series of holes positioned vertically on a riser pipe. Due to the approximation, and rounding errors, it is currently assumed that several preset designs are more accurate than a program that accepts any plant flow rate. The pre-set designs will ensure that there is never a ordering of holes simliar to the optimal orifice configuration. A common error is an orifice pattern of 1, 1, 0, 2, 1. This occurs because in the second row the number of holes requested was a fractional amount and then in the subsequent row the program calls for 1 and a fractional hole which rounds to two holes. Installation of a LFOM for a higher flow rate than necessary won't degrade th the performance and it is a way to ensure quality in the design. Criteria by which the designs are evaluated include: maximum error, number of rows, and the presense of the rounding error.
Designs for
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Pre-Set Flow Rates
Flow Rate (L/min) | LFOM Design | Pipe Diameter (in) | Max Error % | Pi_LfomOrifice(the number of rows) | LFOM Design | ||
|---|---|---|---|---|---|---|---|
100 | 0.398 | 20 | 100 |
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200 | 0.14 | 20 |
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300 | 0.195 | 20 |
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400 | 0.109 | 20 |
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500 | 0.097 | 20 | 600 |
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700 | 0.046 | 20 | 800 |
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1000 900 | 0.049 |
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| 1000 |
| 20 |
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The Mathcad Entrance Tank Code was run for seven flow rates, three Pi_LfomOrifice values, and two initial values for the H.flowloc array. The excel spreadsheet with the original data is available here. The Entrance Tank Code is available throught the SourceForge repository, a storage system. To access the code .............