## 5 Conclusions  
* The fluid flows from the upper part of the jet to the bottom of the jet and forms a semi-closed loop with the reverse flow in the nozzle jet. It can cause a mixing exchange between the jet and the surrounding gas.
* By comparing the results with the literature, this study demonstrates significant advancements in both theoretical understanding and practical applications of energy dissipators. The introduction of fragmentation needles, combined with advanced turbulence modeling and vortex analysis, sets a new standard for energy dissipation efficiency and design flexibility. These contributions not only fill critical knowledge gaps but also provide valuable insights for future research and engineering applications in hydraulic structures.
* Under the same flow rate, the height of the jet gradually decreases with increasing size and number of crushing needles. The more the number of crushing needles, the larger the size, and the larger the Reynolds number, the higher the vertical jet energy dissipation rate and its increase ratio. With an increase in the number of crushing needles, the ratio between the vertical jet energy dissipation rate and the vertical jet energy dissipation rate increases greatly.
* Under the flow conditions studied in this paper, the vertical jet energy dissipation rate under the influence of the crushing needles is greater than the vertical jet energy dissipation rate without the influence of the crushing needles and has better energy dissipation characteristics, indicating that the arrangement of the crushing needles at the nozzle of the vertical pipeline can effectively improve the vertical jet energy dissipation effect and reduce the impact of the jet on the water cushion energy dissipation pool.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app15073560/s1](https://www.mdpi.com/article/10.3390/app15073560/s1)]([https://www.mdpi.com/article/10.3390/app15073560/s1](https://www.mdpi.com/article/10.3390/app15073560/s1)), Figure S1. Turbulence statistical results of velocity field: (**a**) profiles of the averaged vertical and lateral velocities. (**b**) profiles of the averaged lateral velocities. Z is the vertical coordinate. Figure S2. Profiles of the normal Reynolds stress intensity components in the central (y = 0) vertical x-z plane.  
**Author Contributions:** Data curation, H.M.; formal analysis, Y.L.; funding acquisition, X.S.; investigation, H.M.; resources, Y.L.; visualization, X.S. writing--original draft, H.M.; writing--review and editing, Y.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the National Natural Science Foundation of China (Grant No. 51179116) and the Natural Science Foundation of Shanxi Province (Grant No. 202303021211141).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data that support the findings of this study are available from the corresponding author upon reasonable request.  
**Acknowledgments:** The authors appreciate the support of the National Natural Science Foundation of China Grant Program (Grant No. 51179116) and the Natural Science Foundation of Shanxi Province under Grant No. 2303021211141.  
**Conflicts of Interest:** The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.