Hydraulic Efficiency of Grate and Curb Inlets - Urban Drainage and ...

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test data for typical design depths of 0.5 to 1 ft. A 5% reduction in average efficiency error was noted, and a 10% reduction in maximum efficiency error was noted for all test depths over the improved UDFCD methods. UDFCD methods for these inlets were shown to rely heavily on theoretical parameters that can not be physically determined by a user; parameters are instead determined from complex empirical relationships. A comparison between splash-over velocity curves developed for the Type 13 and 16 combination inlets and those for the most similar grate inlets from the USDCM revealed significant differences. The equations provided in the USDCM give an unrealistically high splash-over velocity (on the order of 30 ft/s) for a 10-ft Type 13 or 16 combination inlet, which is in sharp contrast to the 4 ft/s determined from the test data. Original and improved UDFCD methods were most accurate at the lowest flow depth of 0.333 ft. Beyond that depth, the accuracy was very poor. This is likely due to the limitations of the FHWA model used to collect data for development of the equations. For the Type R curb inlet, the improved UDFCD methods were slightly better able to predict the observed efficiency data than the empirical equation for all test depths. A 1.2% improvement in average efficiency error was noted over the empirical equation, and a 15% reduction in maximum efficiency error was noted for all test depths. Typical design depths are 0.5 ft and greater for selection and placement of street inlets (UDFCD, 2008). With this in mind, recommendations for which calculation method to use are given as follows: for the Type 13 and 16 combination inlets the empirical equations are recommended, for the Type R curb inlet the improved UDFCD methods are recommended. For illustration purposes, the observed test data on efficiency are plotted with the empirical efficiency and the efficiency determined from the improved UDFCD methods in Figure 6-1 through Figure 6-3. 78
Observed efficiency 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Match line regression UDFCD new 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Predicted efficiency Figure 6-1: Type 13 combination-inlet efficiency from all improved methods Observed efficiency 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Match line regression UDFCD new 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Predicted efficiency Figure 6-2: Type 16 combination-inlet efficiency from all improved methods 79
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HYDRAULIC EFFICIENCY OF GRATE AND C
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TABLE OF CONTENTS LIST OF FIGURES .
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LIST OF FIGURES Figure 1-1: Map of
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Figure 5-7: Predicted vs. observed
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LIST OF TABLES Table 2-1: Summary o
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LIST OF SYMBOLS, UNITS OF MEASURE,
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S c , Sc, cross slope cross (or lat
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ID mag meter No. QC ® R5 R9 R12 R1
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1 INTRODUCTION A research program w
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1-1 often require use of these thre
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2 LITERATURE REVIEW Urban storm dra
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• All grates showed patterns of i
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Q = Q w + Q s Equation 2-1 where: 2
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Inlet Name Bar P-1-7/8 Bar P-1-7/8-
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2.2.3 Curb Opening Inlets Curb open
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2.3 Manning’s Equation Uniform fl
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where: q 1 = dependent parameter; q
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Q ⎛ L L Qw ⎞ = f ⎜ , ⎟ Equa
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Headbox Pipe Network Inlets Street
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capacity. A similar study performed
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Table 3-3: Test matrix for 0.33-ft
Page 46 and 47: Table 3-5: Test matrix for 1-ft pro
Page 48 and 49: Solid Plexiglas ® was milled to pr
Page 50 and 51: Figure 3-10: Triple No. 13 combinat
Page 52 and 53: Figure 3-16: Single No. 16 combinat
Page 54 and 55: Figure 3-22: Single No. 16 combinat
Page 56 and 57: Note Safety Bar Figure 3-28: R5 wit
Page 58 and 59: Flow entering and exiting the model
Page 60 and 61: Following a standardized testing pr
Page 63 and 64: 4 DATA AND OBSERVATIONS Testing res
Page 65 and 66: Figure 4-2: Type 16 combination-inl
Page 67 and 68: 45 40 35 Captured flow (cfs) 30 25
Page 69 and 70: 5 ANALYSIS AND RESULTS Data selecte
Page 71 and 72: likely due to the nature of the ori
Page 73 and 74: 1 Observed 0.9 0.8 0.7 0.6 0.5 0.4
Page 75 and 76: Total flow (Q) is known from the ob
Page 77 and 78: Observed 1 0.9 0.8 0.7 0.6 0.5 0.4
Page 79 and 80: 1 0.9 Observed 0.8 0.7 0.6 0.5 0.4
Page 81 and 82: The second Pi group is the square o
Page 83 and 84: Table 5-2: Empirical equations for
Page 85 and 86: Agreement is best at the smallest f
Page 87 and 88: Efficiency/base efficiency 2.2 2 1.
Page 89 and 90: were typically seen at higher flow
Page 91 and 92: Average difference in calculated ef
Page 93: Depth (ft) Table 5-3: Efficiency er
Page 98 and 99: Observed efficiency 1 0.9 0.8 0.7 0
Page 101: 7 REFERENCES Bos, M. G. (1989). Dis
Page 105 and 106: (P-1-7/8 grate does not have the 10
Page 107 and 108: Figure A-3: Curved vane grate (UDFC
Page 109 and 110: Figure A-5: 30º-tilt bar grate (UD
Page 111: APPENDIX B ON-GRADE TEST DATA 93
Page 114 and 115: Test ID Number Configuration Table
Page 116 and 117: Table B-3: 2% and 1% on-grade test
Page 118 and 119: Test ID Number Configuration Longit
Page 120 and 121: Test ID Number Configuration Table
Page 122 and 123: Table B-7: Additional debris tests
Page 124 and 125: 106
Page 126 and 127: For the additional sump tests, only
Page 128 and 129: 110
Page 130 and 131: (a) (b) Figure D-2: Type 16 inlet s
Page 132 and 133: (a) (b) (c) Figure D-4: Type R curb
Page 134 and 135: 116
Page 136 and 137: Extent of Flow Station (x) Position
Page 138 and 139: 120
Page 140 and 141: Test ID Number depth (ft) Tw (ft) A
Page 142 and 143: Table F-2: Additional parameters fo
Page 144 and 145: Test ID Number depth (ft) Tw (ft) A
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Test ID Number depth (ft) Tw (ft) A
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130
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132
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Plot of rstudent*pred. Legend: A =
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The REG Procedure Model: MODEL1 Dep
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Plot of logE*pred. Legend: A = 1 ob
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Plot of rstudent*pred. Legend: A =
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142
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144
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Test ID Number Depth (ft) Grates Fl
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Test ID Number Depth (ft) Grates Fl
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Test ID Number Depth Length Flow Ef
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