HY8:Energy Dissipators: Difference between revisions
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Hydraulic Engineering Circular No. 14 (HEC-14 | 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% < | | 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 | | 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:
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 |
- ^ At release point from culvert or channel
- ^ Debris notes: N = none, L = low, M = moderate, H = heavy
- ^ Bed slope must be in the range 4% < So < 25%
- ^ Check headwater for outlet control
- ^ Discharge, Q < 11 m3/s (400 ft3/s) and Velocity, V < 15 m/s (50 ft/s)
- ^ Culvert rise less than or equal to 1500 mm (60 in)
- ^ Drop < 4.6 m (15 ft)
- ^ Drop < 3.7 m (12 ft)
- na = not applicable.
