# Research on Optimization of the Bulb Form of the Bulb Tubular Pump Device for a Low-Head Agricultural Irrigation Pumping Station

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## Abstract

**:**

## 1. Introduction

## 2. Numerical Simulation

#### 2.1. Three-Dimensional Geometric Model

^{3}/S, the single power was 3550 kW, the speed was 85.7 r/min, the head size was 3.15 m, and the impeller diameter range D was 5.14 m. As shown in Figure 1, the bulb tubular pump device consists of components such as the inlet duct, impeller, guide vane, bulb body, and outlet duct. The bulb tubular pump device is a rear-mounted bulb tubular pump device, and the bulb body is placed in the outlet duct. Unlike other types of pumping stations, placing the bulb body inside the pump device will have an impact on the flow of water in the duct and increase hydraulic losses. Therefore, it is necessary to conduct research on the key structural parameters of the bulb body.

#### 2.2. Numerical Simulation

#### 2.2.1. Calculation Method

#### 2.2.2. Computational Grid Independence Analysis

#### 2.2.3. Calculation Parameters and Boundary Condition Setting

^{–4}.

#### 2.2.4. Entropy Production Dissipation Theory

^{−1}), and k is the turbulence energy (m

^{2}/s

^{2}).

^{2}), and $\underset{V}{\to}$ denotes the first grid velocity near the wall (m/s).

## 3. Analysis of Calculation Results

#### 3.1. Analysis on Influencing Factors of Hydraulic Performance of Bulb Section

#### 3.2. Influence of Bulb Tail Shape on Hydraulic Performance

#### 3.3. Influence of Bulb Ratio on Hydraulic Performance

#### 3.4. Influence of Support Shape on Hydraulic Performance

## 4. Conclusions

- (1)
- Because the bulb was in the key position of the flow channel, it affected the flow state in the flow channel and had a significant influence on the efficiency of the entire device. The hydraulic loss of the bulb part is about 40% of the overall hydraulic loss of the pump device, which accounts for the largest proportion of the entire pump device.
- (2)
- Different tail shapes of the bulb had different effects on the flow pattern and the performance of the entire device. The flow pattern distribution at the tail of the bulb was improved to a certain extent by using the elliptical bulb tail. This reduces the hydraulic loss of the bulb section and increases the efficiency of the device by about 5% compared to the hemisphere bulb structure.
- (3)
- The bulb ratio of the bulb with a semi-ellipsoid tail shape was small, the flow area was large, the flow pattern was smoother, and the bulb section had higher efficiency. Schemes 4 and 5 had a small tail entropy output value, small hydraulic loss, and high efficiency. Considering that the pump station was directly connected by the synchronous motor, we selected scheme 5 to facilitate the installation of the motor.
- (4)
- The bulb support is an important internal flow component of the tubular pump unit. A change in its shape had a significant influence on the flow pattern of the water in the pump unit and also on the hydraulic performance of the pump unit. Reasonable shape design of the support parts according to minimum resistance requirements effectively improved the flow pattern, reduced hydraulic losses, and improved the efficiency of the pump unit. Scheme 9’s supports had better hydraulic performance, improved the device efficiency, and achieved the optimization purpose. Therefore, we selected scheme 9 as the bulb optimization scheme. Its geometric characteristics and parameters were as follows: the shape of the bulb tail was oval, the bulb ratio was 0.96, and the shape of the supports was streamlined.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 4.**Streamline cloud diagram of axial velocity in bulb section: (

**a**) 0.9Q

_{d}; (

**b**) 1.0Q

_{d}; (

**c**) 1.1Q

_{d}; (

**d**) 1.2Q

_{d}.

**Figure 5.**Contour image of axial velocity distribution in bulb section: (

**a**) 0.9Q

_{d}; (

**b**) 1.0Q

_{d}; (

**c**) 1.1Q

_{d}; (

**d**) 1.2Q

_{d}.

**Figure 7.**(

**A**) Axial velocity streamline contour chart in the bulb bodies with different tail shapes at design flow rate; (

**B**) Axial velocity contour chart in the bulb bodies with different tail shapes at design flow rate.

**Figure 10.**(

**A**) Axial velocity streamline distribution in bulb bodies with different bulb ratios at design flow rate; (

**B**) Axial surface entropic production distribution cloud in bulb bodies with different bulb ratios at design flow rate.

**Figure 12.**(

**A**) Axial velocity streamline contour chart in the bulb bodies with different bulb support shapes at design flow rate; (

**B**) Axial velocity contour chart in the bulb bodies with different bulb support shapes at design flow rate.

Grid | Impeller Grid/Million | Guide Vane Grid/Million | Passage Inlet Grid/Million | Passage Outlet (Including Bulb) Grid/Million | Total Grid/Million |
---|---|---|---|---|---|

1 | 1.40 | 1.80 | 2.60 | 3.00 | 8.80 |

2 | 1.50 | 1.80 | 2.60 | 3.00 | 8.90 |

3 | 1.60 | 1.80 | 2.60 | 3.00 | 9.00 |

4 | 1.70 | 1.80 | 2.60 | 3.00 | 9.10 |

5 | 1.80 | 1.80 | 2.60 | 3.00 | 9.20 |

6 | 1.90 | 1.80 | 2.60 | 3.00 | 9.30 |

Flow Rate | Hydraulic Loss/M | Passage Inlet | Guide Vane | Bulb | Passage Outlet |
---|---|---|---|---|---|

0.9Q_{d} | 0.663 | 3.66 | 43.06 | 39.30 | 13.98 |

1.0Q_{d} | 0.258 | 15.43 | 28.29 | 35.43 | 20.85 |

1.1Q_{d} | 0.343 | 9.89 | 25.73 | 42.42 | 21.96 |

1.2Q_{d} | 0.484 | 5.95 | 28.97 | 47.43 | 17.65 |

Flow | 0.9Q_{d} | 1.0Q_{d} | 1.1Q_{d} | 1.2Q_{d} |
---|---|---|---|---|

Head/m | 3.56 | 3.27 | 2.89 | 2.38 |

Efficiency/% | 73.87 | 78.75 | 82.17 | 83.28 |

Scheme | Bulb Tail Form | Three-Dimensional Model |
---|---|---|

1 | First straight-line progressive section, then semi-ellipsoid; tail contraction angle is 27 degrees | |

2 | Hemisphere | |

3 | Semi-ellipsoid |

Scheme | $\mathbf{Bulb}\mathbf{Ratio}\left(\frac{{\mathit{d}}_{1}}{\mathit{D}}\right)$ | Three-Dimensional Diagram |
---|---|---|

4 | 0.88 | |

5 | 0.96 | |

6 | 1.04 |

Scheme | Support Shape | Three-Dimensional Model |
---|---|---|

7 | Original scheme | |

8 | Split into two supports | |

9 | Streamline design |

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**MDPI and ACS Style**

Zhang, H.; Liu, J.; Wu, J.; Jiao, W.; Cheng, L.; Yuan, M.
Research on Optimization of the Bulb Form of the Bulb Tubular Pump Device for a Low-Head Agricultural Irrigation Pumping Station. *Agriculture* **2023**, *13*, 1698.
https://doi.org/10.3390/agriculture13091698

**AMA Style**

Zhang H, Liu J, Wu J, Jiao W, Cheng L, Yuan M.
Research on Optimization of the Bulb Form of the Bulb Tubular Pump Device for a Low-Head Agricultural Irrigation Pumping Station. *Agriculture*. 2023; 13(9):1698.
https://doi.org/10.3390/agriculture13091698

**Chicago/Turabian Style**

Zhang, Hongyin, Jianlong Liu, Jinxin Wu, Weixuan Jiao, Li Cheng, and Mingbin Yuan.
2023. "Research on Optimization of the Bulb Form of the Bulb Tubular Pump Device for a Low-Head Agricultural Irrigation Pumping Station" *Agriculture* 13, no. 9: 1698.
https://doi.org/10.3390/agriculture13091698