# Analysis of Hydraulic Performance and Flow Characteristics of Inlet and Outlet Channels of Integrated Pump Gate

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## Abstract

**:**

## 1. Introduction

## 2. Numerical Simulation Model and Method

#### 2.1. Pump Gate Modeling

_{d}= 11.5 L/s, design head H = 2.7569 m. Three-dimensional geometric model of integrated pump gate as shown in Figure 1.

#### 2.2. Mesh Division

_{d}= 11.5 L/s) for mesh-independent analysis. After the grid number reaches 3.03 million, the efficiency of the pump gate basically does not change with the increase of the grid number [11], and this paper determines how to use the grid number of 3.03 million for the subsequent numerical simulation work. Mesh division of each calculation component as shown in Figure 2. The grid-independence results are shown in Figure 3.

#### 2.3. Control Equations, Boundary Conditions, and Calculation Methods

^{3}/s), H

_{1}, H

_{2}are the inlet and outlet section elevations of the integrated pump gate (m), s

_{1}, s

_{2}for the integrated pump gate inlet and outlet section, u

_{1}, u

_{2}for the integrated pump gate inlet and outlet water channel section flow rate at each point (m/s), u

_{t}

_{1}, u

_{t}

_{2}are the normal components of flow velocity (m/s) at each point of the inlet and outlet channel sections of the integrated pump gate, P

_{1}, P

_{2}are the static pressure (Pa) at each point of the inlet and outlet sections of the integrated pump gate, g is the acceleration of gravity (m/s

^{2}).

_{p}is the torque (N-m), ω is the rotational angular speed of the impeller. The hydraulic loss h

_{f}is calculated as [18,19]:

_{1}, E

_{2}are the total energy at the inlet and outlet of the open flow channel, P

_{1}, P

_{2}are the static pressure at the inlet and outlet of the open flow channel (Pa), Z

_{1}, Z

_{2}are the height of the open flow channel inlet and outlet (m), u

_{1}, u

_{2}are the open flow channel inlet and outlet velocity (m/s).

_{u}is the uniformity of axial flow velocity distribution in the characteristic section (%), v

_{ai}is the axial velocity of each calculation unit (m/s), n is the number of calculation units. The velocity weighted average angle is calculated as [21]:

_{ti}is the horizontal velocity (m/s) of each unit in the characteristic section of the flow channel. u

_{ai}is the axial velocity (m/s) of each calculation unit.

## 3. Numerical Simulation Results and Analysis

#### 3.1. Hydraulic Performance Results and Analysis

_{d}), the pump gate is in the high efficiency zone, and the efficiency of the pump gate is around 59~60%. When the flow rate is 5.5~7.5 L/s (0.48~0.65 Q

_{d}), the pump gate is located near the saddle area, and the operation of the pump gate is not stable at this time, so it is recommended to avoid operating in this flow range.

#### 3.2. Analysis of Internal Flow in Inlet Channel

#### 3.2.1. Inlet Channel Streamline and Axial Flow Velocity Distribution

#### 3.2.2. Hydraulic Loss of Inlet Channel

_{f}is positively correlated with the flow rate Q, which approximately satisfies the quadratic function, and the hydraulic loss is the smallest when the inlet flow rate is 8.5 L/s (0.74 Q

_{d}), which is 0.039 m, and the largest when the flow rate is 14.5 L/s (1.26 Q

_{d}), which is 0.100 m. The larger the flow rate, the larger the hydraulic loss, and in this type of pump station, the hydraulic loss of the inlet and outlet channels is a decisive factor in the efficiency of the pump gate. The calculation results show that the average level of hydraulic loss of the inlet channel is about 6 cm, which is in line with the conventional theory and design.

#### 3.3. Analysis of Internal Flow in Outlet Channel

#### 3.3.1. Streamline and Axial Velocity Distribution of Outlet Channel

_{d}), the axial flow velocity at the outlet of the pump gate is about 3.3 m/s; when the flow rate is 11.5~14.5 L/s (Q

_{d}~1.26 Q

_{d}), the axial flow velocity at the outlet is about 4.1 m/s, and then there is a step transition along the outlet direction, due to the existence of vortex, the axial flow velocity above the pump gate is lower. The axial flow velocity above the outlet is low. The existence of the vortex is mainly due to the open outlet upper part of the stagnant water area, where the flow velocity is low due to the rotation of the impeller, the lower and middle water flow velocity is fast, making the formation parallel to the direction of the water flow back vortex.

#### 3.3.2. Hydraulic Loss of Outlet Channel

_{d}). With the increase of the inlet flow rate, the hydraulic loss also gradually increases, reaching a maximum value of 1.933 m at an inlet flow rate of 14.5 L/s (1.26 Q

_{d}).

#### 3.4. Three-Dimensional Flow Regime Analysis

#### 3.4.1. Integrated Pump Gate Three-Dimensional Streamline and Characteristic Cross-Sectional Flow Rate

_{d}), the axial flow velocity in the sections is approximately the same, and only the upper part of the sections is slightly lower. When the flow rate is 14.5 L/s (1.26 Q

_{d}), there is still a circular region of high axial velocity in the section, which is caused by the fact that as the flow rate increases, the flow rate increases and the high velocity region also shifts toward the outlet of the outflow channel. At a flow rate of 8.5 L/s (0.74 Q

_{d}), the area of the high flow velocity region in the slice at D from the guide vane outlet is larger than that in the slice at 3 D from the guide vane outlet, and the area of the high flow velocity region in the slice at 3 D from the guide vane outlet is larger than that in the slice at D from the guide vane outlet for the rest of the flow conditions, This is due to small flow conditions, small flow rate, short distance of high-speed water flow transmission at the outlet of pump gate, and fast dissipation of kinetic energy.

#### 3.4.2. Uniformity of Axial Flow Velocity Distribution and Velocity-Weighted Average Angle of Each Characteristic Section under Design Conditions

## 4. Internal Flow Characteristics Test Analysis

#### 4.1. Introduction to the Pump Gate Test Rig

#### 4.2. Test results and Analysis

#### 4.2.1. Analysis of Flow Characteristics of Open Inlet and Outlet Water Channels

_{d}) are selected for analysis by means of a high-speed camera, as shown in Figure 24.

_{d}), as shown in Figure 25.

#### 4.2.2. Analysis of the Flow Characteristics at the Inlet and Outlet of the Pump Gate Impeller

_{d}), it can be found that the tracer red line converges to the impeller rotation center under the action of low pressure at the impeller inlet of the pump gate, gradually shrinks and swings evenly, there is no cross wrapping at the pump shaft, and the tracer red line at the upper part of the inlet channel faces the pump inlet, which is similar to the numerical calculation result (Figure 6), the slope of the inlet passage provides good inlet conditions for the impeller.

_{d}) can be obtained through the test, and there is an obvious backflow vortex at the outlet of the guide vane, section B-4, the side wall against the lower and bottom tracer red line swing toward the outflow channel, the side wall against the upper tracer red line due to the existence of vortex, swing toward the inlet direction, section B-5, B-6 tracer streamline swing state similar to section B-4, the tracer red line oscillates upwards in the upper part of the outflow channel, while the tracer red line oscillates downwards in the outflow channel, and there is an obvious stratification of the water flow. This phenomenon can also be found through the previous numerical simulation results, which is due to the formation of backflow vortex caused by the opposite axial velocity of the water flow on the upper and lower side of the outlet channel of the pump gate.

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 1.**Three-dimensional geometric model of integrated pump gate. (

**a**) Integrated gate general assembly; (

**b**) Inlet channel; (

**c**) Outlet channel; (

**d**) Gate; (

**e**) Impeller; (

**f**) Guide vane.

**Figure 6.**Cloud diagram of inlet channel streamline and axial flow velocity distribution under different working conditions.

**Figure 7.**Cloud diagram of streamline and pressure distribution at the inlet of pump gate under different working conditions.

**Figure 10.**Streamline and axial velocity distribution of the outlet channel under different flow conditions.

**Figure 11.**Streamline and pressure distribution at the pump gate outlet under different flow conditions.

**Figure 21.**The uniformity of axial flow velocity distribution and velocity-weighted average angle curve of each characteristic section.

**Figure 22.**Schematic diagram of test bench: 1. water inlet tank; 2. water inlet channel support part; 3. open inlet and outlet channels; 4. outlet channel support part; 5. outlet water tank; 6. flange butterfly valve; 7. booster pump; 8. tested integrated pump gate; 9. pipe support; 10. electromagnetic flowmeter; 11. circulating pipeline.

**Figure 23.**Three-dimensional rendering drawing and physical drawing of integral pump gate test stand: (

**a**) Three-dimensional rendering drawing of integrated pump gate test stand; (

**b**) physical drawing of integrated pump gate test stand.

Boundary Conditions | Parameter Setting |
---|---|

Inlet | Mass Flow Rate |

Outlet | Average Static Pressure |

Free liquid level | Symmetry |

Dynamic and static interface | Frozen Rotor |

Static interfaces | None |

Q (L/s) | H (m) | H (%) |
---|---|---|

8.5 (0.74 Q_{d}) | 3.4884 | 49.83 |

9.5 (0.83 Q_{d}) | 3.3126 | 55.85 |

10.5 (0.91 Q_{d}) | 3.0206 | 59.01 |

11.5 (Q_{d}) | 2.7569 | 60.50 |

12.5 (1.09 Q_{d}) | 2.3343 | 59.73 |

13.5 (1.17 Q_{d}) | 1.7245 | 54.87 |

14.5 (1.26 Q_{d}) | 1.0426 | 43.58 |

Characteristic Section Number | Distance from Impeller Inlet L _{1} | Distance from Guide Vane Outlet L_{2} |
---|---|---|

A-1 | 30 D | |

A-2 | 20 D | |

A-3 | 10 D | |

A-4 | 10 D | |

A-5 | 20 D | |

A-6 | 30 D | |

B-1 | 5 D | |

B-2 | 3 D | |

B-3 | D | |

B-4 | D | |

B-5 | 3 D | |

B-6 | 5 D |

**Table 4.**Uniformity of axial flow velocity distribution and velocity-weighted average angle for each characteristic section under design condition.

Evaluation Indicators | SectionA-1 | SectionA-2 | SectionA-3 | SectionB-1 | SectionB-2 | SectionB-3 | SectionA-4 | SectionA-5 | SectionA-6 |
---|---|---|---|---|---|---|---|---|---|

Uniformity of flow rate distribution Vu (%) | 95.42 | 94.18 | 93.95 | 96.72 | 91.15 | 45.33 | 95.37 | 98.26 | 98.25 |

$\mathrm{Velocity}-\mathrm{weighted}\mathrm{average}\mathrm{angle}\overline{\theta}$(°) | 89.93 | 89.71 | 89.54 | 79.47 | 75.30 | 62.01 | 87.95 | 89.67 | 89.96 |

Measurement Items | Name of Measuring Equipment | Model | Scope of Work | Accuracy |
---|---|---|---|---|

Flow rate | Electromagnetic flow meters | ZEF-DN100 | 0~120 m^{3}/h | ±0.5% |

Rotational speed | Laser tachographs | DT-2234C | 0.1~99,999 r/min | ±0.05% |

Flow pattern | High-speed cameras | OLYMPUS i-SPEED 3 | 2000 fpsFull resolutionMaximum 15,0000 fps | ±1 μs |

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**MDPI and ACS Style**

Xie, C.; Xuan, W.; Feng, A.; Sun, F. Analysis of Hydraulic Performance and Flow Characteristics of Inlet and Outlet Channels of Integrated Pump Gate. *Water* **2022**, *14*, 2747.
https://doi.org/10.3390/w14172747

**AMA Style**

Xie C, Xuan W, Feng A, Sun F. Analysis of Hydraulic Performance and Flow Characteristics of Inlet and Outlet Channels of Integrated Pump Gate. *Water*. 2022; 14(17):2747.
https://doi.org/10.3390/w14172747

**Chicago/Turabian Style**

Xie, Chuanliu, Weipeng Xuan, Andong Feng, and Fei Sun. 2022. "Analysis of Hydraulic Performance and Flow Characteristics of Inlet and Outlet Channels of Integrated Pump Gate" *Water* 14, no. 17: 2747.
https://doi.org/10.3390/w14172747