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

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On-grade test data Directly calculate efficiency as Q captured divided by Q Total Determine efficiency from regression equations for type 13, 16, and R inlets Determine efficiency using current UDFCD methods for type 13, 16, and R inlets Determine efficiency using improved UDFCD methods for type 13, 16, and R inlet Compare results for efficiency with test data and recommend improvements Figure 5-1: Analysis flow chart 5.1 Efficiency from UDFCD Methods In this section, efficiency is determined for the Type 13, 16, and R inlets using the currently-accepted calculation methods presented previously in Section 2.2. For the Type 13 and 16 combination inlets, efficiency was determined using Equation 2-1 through Equation 2-4, and Equation 2-7 through Equation 2-10 as a direct calculation. Guidance in the USDCM to ignore the curb component of these combination inlets was followed by applying those equations. It was necessary to match the Type 13 and 16 inlets to comparable inlets from the UDFCD methods given in Section 2.2. From Table 2-4, the Type 13 inlet grate was found to be most similar to the Bar P-1-7/8-4 (also known as a P50x100 in HEC 22) by visual inspection, and the Type 16 grate was most similar to the vane grate. Applicable coefficients from Table 2-4 were used in Equation 2-8 for calculation of splash-over velocity. The local gutter depression (a), shown in Figure 2-2, was determined as a function of cross slope and gutter width. For a cross slope of 1% the value of “a” was 0.13 ft, and for a cross slope of 2% the value of “a” was 0.11 ft. Additional parameters were determined directly from the collected test data. Efficiency was then calculated from Equation 2-10, and compared to the observed efficiency in Figure 5-2 and Figure 5-3. Deviation of UDFCD methods from the observed test data becomes greater with increasing flow depth and increasing inlet length for Type 13 and 16 inlets. Differences in efficiency are 52
likely due to the nature of the original FHWA test data used to develop Equation 2-4 through Equation 2-10 for grate inlets. The FHWA study, summarized in Section 2.1, only tested to a maximum flow depth of 0.45 ft and a maximum inlet length of 4 ft. Therefore, the data would have had to be extrapolated to greater depths and inlet lengths. Analysis of the observed test data presented here does not extrapolate beyond the actual conditions tested. 1 Observed 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1 ft depth 0.5 ft depth 0.33 ft depth Equal 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Predicted R 2 Average efficiency error (%) Maximum efficiency error (%) 0.719 18.8 34.0 Figure 5-2: Predicted vs. observed efficiency for Type 13 combination inlet from UDFCD methods 53
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HYDRAULIC EFFICIENCY OF GRATE AND C
Page 5 and 6:
TABLE OF CONTENTS LIST OF FIGURES .
Page 7 and 8:
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
Page 19 and 20: 1 INTRODUCTION A research program w
Page 21 and 22: 1-1 often require use of these thre
Page 23 and 24: 2 LITERATURE REVIEW Urban storm dra
Page 25 and 26: • All grates showed patterns of i
Page 27 and 28: Q = Q w + Q s Equation 2-1 where: 2
Page 29 and 30: Inlet Name Bar P-1-7/8 Bar P-1-7/8-
Page 31 and 32: 2.2.3 Curb Opening Inlets Curb open
Page 33 and 34: 2.3 Manning’s Equation Uniform fl
Page 35 and 36: where: q 1 = dependent parameter; q
Page 37: Q ⎛ L L Qw ⎞ = f ⎜ , ⎟ Equa
Page 40 and 41: Headbox Pipe Network Inlets Street
Page 42 and 43: capacity. A similar study performed
Page 44 and 45: 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: 5 ANALYSIS AND RESULTS Data selecte
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 96 and 97: test data for typical design depths
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
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106
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For the additional sump tests, only
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110
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(a) (b) Figure D-2: Type 16 inlet s
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(a) (b) (c) Figure D-4: Type R curb
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Page 136 and 137:
Extent of Flow Station (x) Position
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120
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Test ID Number depth (ft) Tw (ft) A
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Table F-2: Additional parameters fo
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Page 146 and 147:
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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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Hydraulic Efficiency of Grate and Curb Inlets - Urban Drainage and ...

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