HY8:Energy Dissipators: Difference between revisions

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Hydraulic Engineering Circular No. 14 (HEC-14) (July 2006) describes several energy dissipating structures that can be used with culverts.  HEC-14 describes procedures that can be used to compute scour hole sizes and design internal and external dissipators.  It outlines the following steps that can be used when designing a culvert:
Hydraulic Engineering Circular No. 14 (HEC-14) describes several energy dissipating structures that can be used with culverts.  HEC-14 describes procedures that can be used to compute scour hole sizes and design internal and external dissipators.  It outlines the following steps that can be used when designing a culvert:


   
   
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| 4 || Flow transitions || na || H || H || H || Desirable
| 4 || Flow transitions || na || H || H || H || Desirable
|- Align=Center  
|- Align=Center  
| 5 || Scour hole || na || H || H || H || Desirable
| 5 || [[HY8:Scour Hole Geometry|Scour hole]] || na || H || H || H || Desirable
|- Align=Center  
|- Align=Center  
| 6 || Hydraulic jump || > 1 || H || H || H || Required
| 6 || Hydraulic jump || > 1 || H || H || H || Required
|- Align=Center  
|- Align=Center  
| 7 || Tumbling flow<ref name="Tumbling fow">Bed slope must be in the range 4% < S<sub>o</sub> < 25%</ref> || > 1 || M || L || L || Not needed
| 7 || [[HY8:Tumbling Flow|Tumbling flow]]<ref name="Tumbling fow">Bed slope must be in the range 4% < S<sub>o</sub> < 25%</ref> || > 1 || M || L || L || Not needed
|- Align=Center  
|- Align=Center  
| 7 || Increased resistance<ref name="Inc resist">Check headwater for outlet control</ref> || na || M || L || L || Not needed
| 7 || [[HY8:Increased Resistance in Culverts|Increased resistance]]<ref name="Inc resist">Check headwater for outlet control</ref> || na || M || L || L || Not needed
|- Align=Center  
|- Align=Center  
| 7 || USSBR Type IX baffled apron || < 1 || M || L || L || Not needed
| 7 || [[HY8:USBR Type IX Baffled Apron|USSBR Type IX baffled apron]] || < 1 || M || L || L || Not needed
|- Align=Center  
|- Align=Center  
| 7 || Broken-back culvert || > 1 || M || L || L || Desirable
| 7 || Broken-back culvert || > 1 || M || L || L || Desirable
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| 8 || USBR Type II stilling basin || 4.5 to 17 || M || L || M  || Required
| 8 || USBR Type II stilling basin || 4.5 to 17 || M || L || M  || Required
|- Align=Center  
|- Align=Center  
| 8 || USBR Type IV stilling basin || 2.5 to 4.5 || M || L || M || Required
| 8 || [[HY8:USBR Type IV Stilling Basin|USBR Type IV stilling basin]] || 2.5 to 4.5 || M || L || M || Required
|- Align=Center  
|- Align=Center  
| 8 || SAF stilling basin || 1.7 to 17 || M || L || M || Required
| 8 || [[HY8:Saint Anthony Falls (SAF Stilling Basin)|SAF stilling basin]] || 1.7 to 17 || M || L || M || Required
|- Align=Center  
|- Align=Center  
| 9 || CSU rigid boundary basin || < 3 || M || L || M || Not needed
| 9 || [[HY8:Colorado State University (CSU) Rigid Boundary Basin|CSU rigid boundary basin]] || < 3 || M || L || M || Not needed
|- Align=Center  
|- Align=Center  
| 9 || Contra Costa basin || < 3 || H || M || M || < 0.5D
| 9 || [[HY8:Contra Costa Basin|Contra Costa basin]] || < 3 || H || M || M || < 0.5D
|- Align=Center  
|- Align=Center  
| 9 || Hook basin || 1.8 to 3 || H || M || M || Not needed
| 9 || [[HY8:Hook Basin|Hook basin]] || 1.8 to 3 || H || M || M || Not needed
|- Align=Center  
|- Align=Center  
| 9 || USBR Type VI impact basin<ref name="USBR VI">Discharge, Q < 11 m<sup>3</sup>/s (400 ft<sup>3</sup>/s) and Velocity, V < 15 m/s (50 ft/s)</ref>  
| 9 || [[HY8:USBR Type VI Impact Basin|USBR Type VI impact basin]]<ref name="USBR VI">Discharge, Q < 11 m<sup>3</sup>/s (400 ft<sup>3</sup>/s) and Velocity, V < 15 m/s (50 ft/s)</ref>  
| na || M || L || L || Desirable
| na || M || L || L || Desirable
|- Align=Center  
|- Align=Center  
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{{HY8Main}}
{{HY8Main}}
[[Category:Energy Dissipators|E]]

Latest revision as of 16:00, 1 December 2016

Hydraulic Engineering Circular No. 14 (HEC-14) describes several energy dissipating structures that can be used with culverts. HEC-14 describes procedures that can be used to compute scour hole sizes and design internal and external dissipators. It outlines the following steps that can be used when designing a culvert:


HY8image9.jpg


HEC-14 also describes the energy dissipators and their limitations as follows:

Chapter Dissipator Type Froude Number[1] (Fr) Allowable Debris[2] Tailwater (TW)
Silt/Sand Boulders Floating
4 Flow transitions na H H H Desirable
5 Scour hole na H H H Desirable
6 Hydraulic jump > 1 H H H Required
7 Tumbling flow[3] > 1 M L L Not needed
7 Increased resistance[4] na M L L Not needed
7 USSBR Type IX baffled apron < 1 M L L Not needed
7 Broken-back culvert > 1 M L L Desirable
7 Outlet weir 2 to 7 M L M Not needed
7 Outlet drop/weir 3.5 to 6 M L M Not needed
8 USBR Type II stilling basin 4.5 to 17 M L M Required
8 USBR Type IV stilling basin 2.5 to 4.5 M L M Required
8 SAF stilling basin 1.7 to 17 M L M Required
9 CSU rigid boundary basin < 3 M L M Not needed
9 Contra Costa basin < 3 H M M < 0.5D
9 Hook basin 1.8 to 3 H M M Not needed
9 USBR Type VI impact basin[5] na M L L Desirable
10 Riprap basin < 3 H H H Not needed
10 Riprap apron[6] na M L L Desirable
11 Straight drop structure[7] < 1 H L M Required
11 Box inlet drop structure[8] < 1 H L M Required
12 USACE stilling well na M L N Desirable


  1. ^ At release point from culvert or channel
  2. ^ Debris notes: N = none, L = low, M = moderate, H = heavy
  3. ^ Bed slope must be in the range 4% < So < 25%
  4. ^ Check headwater for outlet control
  5. ^ Discharge, Q < 11 m3/s (400 ft3/s) and Velocity, V < 15 m/s (50 ft/s)
  6. ^ Culvert rise less than or equal to 1500 mm (60 in)
  7. ^ Drop < 4.6 m (15 ft)
  8. ^ Drop < 3.7 m (12 ft)
na = not applicable.


v • e
HY-8
Introduction:Getting Started   •   Layout   •   Vena Contracta   •   Building a Project   •   Locate Project   •   Culvert Crossing Data   •   Run Analysis   •   Report Generation
Crossing and Culvert Data:Crossings   •   Discharge Data   •   Roadway Data   •   Tailwater Data   •   Irregular Channel   •   Culvert Data   •   Site Data   •   Culvert Invert Data   •   Embankment Toe Data
AnalysisProject Units   •   Roadway Overtopping   •   Inlet Control Computations   •   Outlet Control Computations   •   Tables and Plots
Energy DissipationScour Hole Geometry   •   Increased Resistance   •   Tumbling Flow   •   USBR Type IX Baffled Apron   •   Drop Structures   •   Stilling Basins   •   Streambed Level Structures
MethodsAquatic Organism Passage   •   Low Flow Hydraulics
TroubleshootingDifferences from DOS HY-8   •   Limitations   •   HY-8 User Manual
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