| Description |
v, 84 leaves : illustrations, photographs ; 29 cm |
| Summary |
"1. The Froude number criterion for weir flow was shown to be sound and accurate by experimental verification of the theoretical correlation of Froude number and critical depth. It was proved that sub-critical, critical and super-critical flows are correctly identified by the Froude number. 2. In order to accurately determine the Froude number, the actual flow section at the weir crest must be known. Because of end contractions, it does not have the same dimensions as the weir opening. For the Cipoletti weir, it is the product of the length of the crest and the crest depth, i.e., A= by. Thus, it is seen that the geometric shape of the actual flow section, as well as the dimensions, may differ from the weir opening due to the contractions. 3. The assumption of a hypothetical channel for the computation of critical depth was shown to be a legitimate one. Here, too, it is necessary to allow for the effects of end contractions. 4. The H/P ratio in no way affected the Froude number as a parameter of open channel flow. 5. A graph of N[subscript f] versus Y/Y[subscript C] indicated the possibility of a better weir flow equation, one derived on the basis of critical depth and capable of giving accurate results without the use of variable coefficients. Through use of Eq. #13 and Fig. 19, this method of calculating the discharge was tested and found to be accurate. 6. The accuracy of Eq. #13 is dependent upon the accuracy of the graph in Fig. 19. The author therefore recommends that the study of the correlation of N[subscript f] and 59 Y/Y[subscript C] be continued and broadened. From such an investigation, if of sufficient scope and precision, a complete and accurate graph could be prepared, thus making possible accurate results from Eq. #13 for any weir, without the need for prior calibration or the use of experimentally determined coefficients. 7. The author realizes that, although the results and correlations obtained by this investigation substantiate the conclusions reached, additional research is needed to verify and more fully explain them. Consequently, it is recommended that this investigation be continued for other types and sizes of weirs "--Summary and Recommendations, leaves 58-59. |
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