Experimental Investigation of the Energy Dissipation Efficiency of a Vortex Drop Shaft with a Spiral Inlet | ||
| تحقیقات مهندسی سازه های آبیاری و زهکشی | ||
| Volume 26, Autumn - Serial Number 100, September 2025, Pages 33-17 PDF (1.15 M) | ||
| Document Type: Original Article | ||
| DOI: 10.22092/idser.2025.370674.1630 | ||
| Authors | ||
| Saeed Akbari Zade1; Ehsan Fadaei-Kermani* 2; Mahnaz Ghaeini-Hessaroeyeh3 | ||
| 1M.Sc. Graduate, Department of Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran | ||
| 2Assistant Professor, Department of Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran | ||
| 3Professor, Department of Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran | ||
| Abstract | ||
| Extended Abstract Introduction Urban sewage collection systems in areas with rugged topography present significant hydraulic challenges. Steep slopes and substantial elevation differences generate high kinetic energy in the flow. Without proper control, this excess energy leads to adverse consequences, including erosion and degradation of the channel bed and walls. Further issues may involve structural damage and vibrations induced by highenergy flow, the entrainment of large volumes of air due to free-falling sewage, and the potential for water hammer in closed systems. To address these challenges, vortex drop structures have been introduced as an efficient engineering solution. These structures establish a controlled vortex flow pattern within a vertical shaft, thereby dissipating the incoming flow's excess energy in an effective and manageable manner. Methodology In the present study, a physical model of a vortex drop structure was constructed to investigate its hydraulic performance, including the spiral inlet and the shaft. Furthermore, since the structure's performance in flow energy dissipation is significantly influenced by the upstream and downstream hydraulic conditions and geometry, the rate of flow energy dissipation by the structure was measured. A 1:10 scale physical model of the East Tehran Sewer Vortex Drop Structure was constructed in the Hydraulic Structures Laboratory of Shahid Bahonar University of Kerman, Iran. The model comprises a rectangular approach channel, a tangential vortex inlet, a drop shaft, an energy dissipator, and a rectangular outlet conduit. In this study, a spiral inlet with different outlet diameters was employed. The inlet channel, with a rectangular cross-section, conveys the flow to the tangential inlet structure. This channel measures 0.18 m in width (B) and 0.21 m in height. Downstream of the vortex drop structure, the flow exits via a rectangular outlet conduit measuring 0.18 m in width and 0.24 m in height. The model begins with an initial reservoir; upon filling, water enters the structure through the inlet channel. The wall height of the inlet channel is 0.24 m. Four different flow rates were used in this experiment: 10.67, 14.55, 19.40, and 25.22 liters per second, respectively. Results and Discussion In the present study, the flow behavior within different sections of the vortex drop structure, including the inlet channel, the spiral inlet structure, and the outlet channel (energy dissipator), was investigated. Subsequently, the influence of three parameters including: flow rate (Q), inlet structure diameter (d), and the ratio of sump depth to shaft diameter (Hs/D) on the energy dissipation efficiency (EDE) was examined. Theeffect of these parameters was evaluated in three stages: first, each parameter was assessed individually, then in pairwise combinations, and finally all three parameters were evaluated together. The results indicate that flow rate had the greatest influence on EDE. The highest efficiency (92.79%) occurred at a flow rate of 10.67 L/s, while the lowest (88.93%) corresponded to 25.22 L/s. Consequently, EDE was found to decrease with increasing flow rate. The simultaneous effect of all three parameters (diameter, flow rate, and sump depth) on energy dissipation efficiency shows that, for a 12 cm diameter and a flow rate of 10.67 L/s, the highest efficiency of 94.59% corresponds to Hs/D=1. For the same diameter and a flow rate of 25.22 L/s, the highest efficiency is 88.92% for Hs/D=1. For a 16 cm diameter and a flow rate of 10.67 L/s, the highest efficiency is 94.08% for Hs/D=1. For this same diameter and a flow rate of 25.22 L/s, the highest efficiency is 90.35% for Hs/D=2. Conclusions In the present research, a physical model of a sewer vortex drop shaft with a spiral inlet was investigated in the Hydraulic Structures Laboratory at Shahid Bahonar University of Kerman. This study examined the effect of three parameters including discharge (Q), the diameter of the inlet structure (d) and the ratio of the depth of sump to the drop shaft diameter (HS/D) on energy dissipation efficiency (EDE). Separate analysis of the individual parameters revealed that the influence of flow discharge (Q) on EDE was greater than that of the other two parameters (diameter and sump depth ratio), accounting for 79.92% of the effect. The two-parameter analysis concerning the interaction of diameter and discharge on EDE showed that at a discharge of Q=10.67 L/s, the highest EDE (93.15%) was achieved with a 12 cm diameter. Furthermore, when the discharge increased to Q=25.22 L/s, the maximum EDE (89.25%) was recorded for the 16 cm diameter. Regarding the combined effect of diameter and sump depth ratio on EDE, the results indicated that for a 12 cm diameter, the peak EDE (92.21%) occurred when HS/D=1, meaning the sump depth was equal to the drop shaft diameter. The results of this study confirm that all three parameters—flow discharge, inlet diameter, and sump depth—affect the energy dissipation efficiency (EDE), with flow discharge exerting the greatest influence. Future work should investigate the effect of other geometric parameters of the spiral inlet, particularly the slope of the inlet channel bed and the slope of the inlet structure itself, on the EDE of vortex drop shafts. Keywords: Energy dissipation efficiency, Discharge, Vortex drop structure, Laboratory model, Spiral inlet. Acknowledgments The authors would like to thank all participants of the present study, especially the civil engineering department of the Shahid Bahonar University of Kerman which made this research possible. Conflict of Interest The authors declared no potential conflicts of interest concerning the research, authorship, and publication of this article. Funding The authors received no financial support for the research, authorship, and publication of this article . Data Availability Statements Data Availability Statement: All information and results are presented in the text of the article. Authors’ contribution All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by all authors. The first draft of the manuscript was written by E. F.K. and all authors commented on previous versions of the manuscript (S. A.Z., E. F.K., and M. Gh.H.). The final revisions have been applied by E. F.K., and M. Gh.H. Moreover, all authors have read and approved the final manuscript. | ||
| Keywords | ||
| Energy dissipation efficiency; Discharge; Vortex drop structure; Laboratory model; Spiral inlet | ||
| References | ||
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