[7969] | 1 | #! /usr/bin/python |
---|
| 2 | |
---|
| 3 | # To change this template, choose Tools | Templates |
---|
| 4 | # and open the template in the editor. |
---|
| 5 | |
---|
| 6 | __author__="steve" |
---|
| 7 | __date__ ="$23/08/2010 5:18:51 PM$" |
---|
| 8 | |
---|
| 9 | |
---|
| 10 | |
---|
[7977] | 11 | def boyd_box(culvert): |
---|
[7969] | 12 | """Boyd's generalisation of the US department of transportation culvert methods |
---|
| 13 | |
---|
| 14 | WARNING THIS IS A SIMPLISTIC APPROACH and OUTLET VELOCITIES ARE LIMITED TO EITHER |
---|
| 15 | FULL PIPE OR CRITICAL DEPTH ONLY |
---|
| 16 | For Supercritical flow this is UNDERESTIMATING the Outlet Velocity |
---|
| 17 | The obtain the CORRECT velocity requires an iteration of Depth to Establish |
---|
| 18 | the Normal Depth of flow in the pipe. |
---|
| 19 | |
---|
| 20 | It is proposed to provide this in a seperate routine called |
---|
| 21 | boyd_generalised_culvert_model_complex |
---|
| 22 | |
---|
| 23 | The Boyd Method is based on methods described by the following: |
---|
| 24 | 1. |
---|
| 25 | US Dept. Transportation Federal Highway Administration (1965) |
---|
| 26 | Hydraulic Chart for Selection of Highway Culverts. |
---|
| 27 | Hydraulic Engineering Circular No. 5 US Government Printing |
---|
| 28 | 2. |
---|
| 29 | US Dept. Transportation Federal Highway Administration (1972) |
---|
| 30 | Capacity charts for the Hydraulic design of highway culverts. |
---|
| 31 | Hydraulic Engineering Circular No. 10 US Government Printing |
---|
| 32 | These documents provide around 60 charts for various configurations of culverts and inlets. |
---|
| 33 | |
---|
| 34 | Note these documents have been superceded by: |
---|
| 35 | 2005 Hydraulic Design of Highway Culverts, Hydraulic Design Series No. 5 (HDS-5), |
---|
| 36 | Which combines culvert design information previously contained in Hydraulic Engineering Circulars |
---|
| 37 | (HEC) No. 5, No. 10, and No. 13 with hydrologic, storage routing, and special culvert design information. |
---|
| 38 | HEC-5 provides 20 Charts |
---|
| 39 | HEC-10 Provides an additional 36 Charts |
---|
| 40 | HEC-13 Discusses the Design of improved more efficient inlets |
---|
| 41 | HDS-5 Provides 60 sets of Charts |
---|
| 42 | |
---|
| 43 | In 1985 Professor Michael Boyd Published "Head-Discharge Relations for Culverts", and in |
---|
| 44 | 1987 published "Generalised Head Discharge Equations for Culverts". |
---|
| 45 | These papers reviewed the previous work by the US DOT and provided a simplistic approach for 3 configurations. |
---|
| 46 | |
---|
| 47 | It may be possible to extend the same approach for additional charts in the original work, but to date this has not been done. |
---|
| 48 | The additional charts cover a range of culvert shapes and inlet configurations |
---|
| 49 | |
---|
| 50 | """ |
---|
| 51 | |
---|
| 52 | # Calculate flows for inflow control |
---|
| 53 | |
---|
| 54 | Q_inflow_unsubmerged = 0.540*g**0.5*width*inflow_specific_energy**1.50 # Flow based on inflow Ctrl inflow Unsubmerged |
---|
| 55 | Q_inflow_submerged = 0.702*g**0.5*width*height**0.89*inflow_specific_energy**0.61 # Flow based on inflow Ctrl inflow Submerged |
---|
| 56 | |
---|
| 57 | if log_filename is not None: |
---|
| 58 | s = 'Q_inflow_unsubmerged = %.6f, Q_inflow_submerged = %.6f' %(Q_inflow_unsubmerged, Q_inflow_submerged) |
---|
| 59 | log_to_file(log_filename, s) |
---|
| 60 | |
---|
| 61 | # FIXME(Ole): Are these functions really for inflow control? |
---|
| 62 | if Q_inflow_unsubmerged < Q_inflow_submerged: |
---|
| 63 | Q = Q_inflow_unsubmerged |
---|
| 64 | dcrit = (Q**2/g/width**2)**0.333333 |
---|
| 65 | if dcrit > height: |
---|
| 66 | dcrit = height |
---|
| 67 | flow_area = width*dcrit |
---|
| 68 | outflow_culvert_depth = dcrit |
---|
| 69 | case = 'inflow unsubmerged Box Acts as Weir' |
---|
| 70 | else: |
---|
| 71 | Q = Q_inflow_submerged |
---|
| 72 | flow_area = width*height |
---|
| 73 | outflow_culvert_depth = height |
---|
| 74 | case = 'inflow submerged Box Acts as Orifice' |
---|
| 75 | |
---|
| 76 | dcrit = (Q**2/g/width**2)**0.333333 |
---|
| 77 | |
---|
| 78 | outflow_culvert_depth = dcrit |
---|
| 79 | if outflow_culvert_depth > height: |
---|
| 80 | outflow_culvert_depth = height # Once again the pipe is flowing full not partfull |
---|
| 81 | flow_area = width*height # Cross sectional area of flow in the culvert |
---|
| 82 | perimeter = 2*(width+height) |
---|
| 83 | case = 'inflow CTRL outflow unsubmerged PIPE PART FULL' |
---|
| 84 | else: |
---|
| 85 | flow_area = width * outflow_culvert_depth |
---|
| 86 | perimeter = width+2*outflow_culvert_depth |
---|
| 87 | case = 'inflow CTRL Culvert is open channel flow we will for now assume critical depth' |
---|
| 88 | |
---|
| 89 | if delta_total_energy < inflow_specific_energy: |
---|
| 90 | # Calculate flows for outflow control |
---|
| 91 | |
---|
| 92 | # Determine the depth at the outflow relative to the depth of flow in the Culvert |
---|
| 93 | if outflow_depth > height: # The outflow is Submerged |
---|
| 94 | outflow_culvert_depth=height |
---|
| 95 | flow_area=width*height # Cross sectional area of flow in the culvert |
---|
| 96 | perimeter=2.0*(width+height) |
---|
| 97 | case = 'outflow submerged' |
---|
| 98 | else: # Here really should use the Culvert Slope to calculate Actual Culvert Depth & Velocity |
---|
| 99 | dcrit = (Q**2/g/width**2)**0.333333 |
---|
| 100 | outflow_culvert_depth=dcrit # For purpose of calculation assume the outflow depth = Critical Depth |
---|
| 101 | if outflow_culvert_depth > height: |
---|
| 102 | outflow_culvert_depth=height |
---|
| 103 | flow_area=width*height |
---|
| 104 | perimeter=2.0*(width+height) |
---|
| 105 | case = 'outflow is Flowing Full' |
---|
| 106 | else: |
---|
| 107 | flow_area=width*outflow_culvert_depth |
---|
| 108 | perimeter=(width+2.0*outflow_culvert_depth) |
---|
| 109 | case = 'outflow is open channel flow' |
---|
| 110 | |
---|
| 111 | hyd_rad = flow_area/perimeter |
---|
| 112 | |
---|
| 113 | if log_filename is not None: |
---|
| 114 | s = 'hydraulic radius at outflow = %f' % hyd_rad |
---|
| 115 | log_to_file(log_filename, s) |
---|
| 116 | |
---|
| 117 | # outflow control velocity using tail water |
---|
| 118 | culvert_velocity = sqrt(delta_total_energy/((sum_loss/2/g)+(manning**2*culvert_length)/hyd_rad**1.33333)) |
---|
| 119 | Q_outflow_tailwater = flow_area * culvert_velocity |
---|
| 120 | |
---|
| 121 | if log_filename is not None: |
---|
| 122 | s = 'Q_outflow_tailwater = %.6f' % Q_outflow_tailwater |
---|
| 123 | log_to_file(log_filename, s) |
---|
| 124 | Q = min(Q, Q_outflow_tailwater) |
---|
| 125 | |
---|
| 126 | return Q |
---|
| 127 | |
---|
| 128 | |
---|
| 129 | if __name__ == "__main__": |
---|
| 130 | |
---|
| 131 | |
---|
| 132 | g=9.81 |
---|
| 133 | culvert_slope=0.1 # Downward |
---|
| 134 | |
---|
| 135 | inlet_depth=2.0 |
---|
| 136 | outlet_depth=0.0 |
---|
| 137 | |
---|
| 138 | inlet_velocity=0.0, |
---|
| 139 | outlet_velocity=0.0, |
---|
| 140 | |
---|
| 141 | culvert_length=4.0 |
---|
| 142 | culvert_width=1.2 |
---|
| 143 | culvert_height=0.75 |
---|
| 144 | |
---|
| 145 | culvert_type='box' |
---|
| 146 | manning=0.013 |
---|
| 147 | sum_loss=0.0 |
---|
| 148 | |
---|
| 149 | inlet_specific_energy=inlet_depth #+0.5*v**2/g |
---|
| 150 | z_in = 0.0 |
---|
| 151 | z_out = -culvert_length*culvert_slope/100 |
---|
| 152 | E_in = z_in+inlet_depth # + |
---|
| 153 | E_out = z_out+outlet_depth # + |
---|
| 154 | delta_total_energy = E_in-E_out |
---|
| 155 | |
---|
| 156 | Q = boyd_box(culvert_height, culvert_width, culvert_width, inlet_specific_energy) |
---|
| 157 | |
---|
| 158 | print 'Q ',Q |
---|