# Hydraulic Jump and Energy Dissipation with Sluice Gate

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Methodology and Experiment

#### 2.1. Experiment Equipment and Method

^{3}/s. However, given the channel size and to ensure constant flow maintenance, 0.026 m

^{3}/s was supplied as the maximum. The variation of the pressure head caused by the installation of the weir could be observed through the piezometers. In order to measure detailed hydraulic characteristics, the 2-D velocity meter (VP1200, KENEK Corp., Tokyo, Japan), which uses very thin sensor needle, was used to minimize flow interference.

**Figure 1.**Structure diagram of channel. (

**a**) Cross-sectional view with piezometer; (

**b**) Floor plan showing the piezometer hole in the channel; and (

**c**) weir and the channel.

**Figure 2.**Overflow-type fixed weir (

**a**) plan of fixed weir installation; (

**b**) photo of weir installed in the channel.

**Figure 3.**Sluice gate-type movable weir (

**a**) plan of sluice gate installation; (

**b**) photo of sluice gate installed in the channel.

Mean Downstream Depth | Height of Energy Dissipator (Hb) | ||
---|---|---|---|

5% | 10% | 15% | |

100 mm | 5 mm | 10 mm | 15 mm |

**Figure 5.**Measurement regions of fixed weir and movable weir (

**a**) Measurement point of fixed weir and (

**b**) Measurement point of movable weir.

- (1)
- Region 1: A supercritical flow region formed when water is discharged by the sluice gate-type movable weir. The flow conditions in Region 1 and associated Froude number are used to describe each experiment.
- (2)
- Region 2: Hydraulic jumps appear in this region in the discharged water flow of the sluice gate-type movable weir. The hydraulic jump lengths are calculated from the existing equations.
- (3)
- Region 3: The discharged flow stabilizes after the hydraulic jumps in this region to show a similar flow to that of the fixed weirs.
- (4)
- Region 4: The upstream domain of the weir region.

Flow Rate (m^{3}/s/m) | Openness Height (m) | Remarks |
---|---|---|

0.036 | 0.026 | There are additional openness heights (m) of extended cases for Chapter 5 (Energy dissipation) (0.036, 0.039, 0.042 and 0.045) |

0.044 | 0.036 | |

0.052 | 0.036 |

#### 2.2. Changes in Energy after Weir Installation

^{3}/s/m) is a unit of water flow rate in the channel.

_{1}and h

_{2}are the same. However, the specific energy curve shows that the specific energy of h

_{2}, E

_{2}, is smaller than the specific energy of h

_{1}, E

_{1}, by $\u2206E$. This is the energy loss due to the hydraulic jump.

_{1}and expressed by the post-hydraulic jump Froude Numbers as Fr

_{1},

_{1}regarding the pre-hydraulic jump water level and hydraulic jump-caused energy loss.

_{1}, is,

_{1},

## 3. Results

#### 3.1. Flow Changed with Overflow-Type Fixed Weir and Sluice Gate-Type Mobile Weir

Flow Rate (m^{3}/s/m) | q (m^{3}/s/m) | ${v}_{4}$ (m/s) | ${h}_{4}$ (m) | $F{r}_{4}$ |
---|---|---|---|---|

Fixed weir | 0.036 | 0.19 | 0.19 | 0.14 |

0.044 | 0.20 | 0.22 | 0.16 | |

0.052 | 0.21 | 0.25 | 0.19 | |

Sluice gate | 0.036 | 0.19 | 0.19 | 0.14 |

0.044 | 0.20 | 0.22 | 0.16 | |

0.052 | 0.20 | 0.26 | 0.19 |

_{1,}and Figure 6 shows the hydraulic jump lengths per unit flow.

Q (m^{3}/s/m) | Fixed Weir | Sluice Gate | $\u2206{L}_{j}/{h}_{1}$ | ||||
---|---|---|---|---|---|---|---|

${h}_{1}$ (m) | ${L}_{j}/{h}_{1}$ | Fr | ${h}_{1}$ | ${L}_{j}/{h}_{1}$ | Fr | ||

0.036 | 0.02 | 55.30 | 3.36 | 0.02 | 90.55 | 3.16 | 35.25 (64%) |

0.044 | 0.02 | 78.26 | 3.56 | 0.03 | 105.26 | 3.43 | 27.00 (35%) |

0.052 | 0.03 | 91.25 | 3.89 | 0.03 | 112.32 | 3.74 | 21.07 (23%) |

^{3}/s/m was 55.30, and that of the movable weir was 90.55. When the flow was 0.044 m

^{3}/s/m, the dimensionless value of the fixed weir was 78.26 and that of the movable weir was 105.26. When the flow was 0.052 m

^{3}/s/m, the dimensionless value of the fixed weir was 91.25, and that of the sluice gate-type movable weir was 112.32. The lower the flow, the more the gap between the two values increased, and the maximum increase of 64% was recorded when the flow was 0.036 m

^{3}/s/m under the sluice gate-type movable weir.

#### 3.2. Flow Changes According to Different Openness Heights

^{3}/s/m than at 0.036 m

^{3}/s/m by 20 mm or more. Higher water levels affected the upstream flow, thus reducing hydraulic jump sizes as well as hydraulic jump lengths to a considerable extent. In particular, if a movable weir was high, the hydraulic jump was shortened. In this case, the water level of the outlet area grew higher, the velocity decreased and hydraulic jump did not occur.

_{3}) is the same. However, the discharge water depth reduction in the case of discharge results in conjugate depth elevation and Froude number increases. Therefore, the conjugate depth and Froude numbers have a proportional relation. However, if water is discharged while keeping the Froude number the same, the flow rate increases to also increase the post-hydraulic water level as well as the corresponding conjugate depth, as shown in Figure 8.

## 4. Hydraulic Jump Length Calculation Equation

_{s}/L) was found to be proportional to the Froude numbers, and the deviation (R

^{2}) was 0.86, representing a close relationship with the proposed regression equation.

## 5. Energy Reduction in Energy Dissipator

#### 5.1. Energy Reduction According to Dissipator Installation Heights

^{3}/s/m. If the energy dissipators were not installed, the movable weir openness height was lowered to create supercritical flow. In this case, a 0.5–3.9 m flow stabilization distance was found to be required. However, with the energy dissipators in place, hydraulic jump occurred in the movable weir downstream, shortening the flow stabilization distance to 0.4–0.8 m, approximately a 1/3 reduction from the non-installation case. Additionally, with the energy dissipator in place, the higher the movable weir openness heights were, the shorter the flow stabilization distance was.

Height of Dissipator | Openness Height (m) | Fr | E_{1} | E_{3} | ΔE | Loss | |
---|---|---|---|---|---|---|---|

Observed | Calculated | ||||||

No issipator | 0.036 | 3.43 | 153.60 | 118.93 | 34.67 | 23% | 32% |

0.039 | 3.16 | 144.24 | 115.06 | 29.18 | 20% | 28% | |

0.042 | 3.14 | 144.94 | 117.29 | 27.65 | 19% | 28% | |

5% of water depth | 0.036 | 3.07 | 136.81 | 113.46 | 23.35 | 17% | 27% |

0.039 | 2.99 | 139.77 | 115.58 | 24.19 | 17% | 26% | |

0.042 | 2.59 | 129.74 | 113.11 | 16.63 | 13% | 19% | |

10% of water depth | 0.036 | 2.81 | 131.91 | 111.72 | 20.20 | 15% | 23% |

0.039 | 2.17 | 123.36 | 113.49 | 9.87 | 8% | 12% | |

0.042 | 2.51 | 127.92 | 112.80 | 15.12 | 12% | 18% | |

15% of water depth | 0.036 | 2.75 | 129.97 | 109.07 | 20.90 | 16% | 22% |

0.039 | 2.58 | 130.16 | 110.13 | 20.03 | 15% | 19% | |

0.042 | 2.43 | 128.45 | 112.76 | 15.69 | 12% | 16% |

#### 5.2. Energy Dissipation according to Energy Dissipator Installation Location

## 6. Conclusion and Summary

## Acknowledgments

## Author Contributions

## Conflicts of Interest

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**MDPI and ACS Style**

Kim, Y.; Choi, G.; Park, H.; Byeon, S.
Hydraulic Jump and Energy Dissipation with Sluice Gate. *Water* **2015**, *7*, 5115-5133.
https://doi.org/10.3390/w7095115

**AMA Style**

Kim Y, Choi G, Park H, Byeon S.
Hydraulic Jump and Energy Dissipation with Sluice Gate. *Water*. 2015; 7(9):5115-5133.
https://doi.org/10.3390/w7095115

**Chicago/Turabian Style**

Kim, Youngkyu, Gyewoon Choi, Hyoseon Park, and Seongjoon Byeon.
2015. "Hydraulic Jump and Energy Dissipation with Sluice Gate" *Water* 7, no. 9: 5115-5133.
https://doi.org/10.3390/w7095115