Junction Chamber at Vortex Drop Shaft: Case Study of Cossonay (original) (raw)
Related papers
Modelling for Simplified Vortex Manhole
International journal of engineering research and technology, 2017
Vortex drop manhole has been improved to solve number of problems associated with conventional drop systems. It dissipates the flow energy, protecting the drop structure from intensive corrosion and abrasive wear. The aim of this present study is to investigate the hydraulic performance of a simplified eccentric vortex drop shaft in order to keep the configuration of vortex shaft elements as simple as possible to facilitate its construction and minimize the construction and maintenance cost ,at the same time be ensured that the vortex shaft hydraulically efficient and stable. Two models have been constructed to investigate the use of centric and eccentric vertical shaft. Results showed that the use of eccentric chamber reduces the vortex chamber height by 25% and it is allowed to pass 19% flow rates more than the centric chamber. Results also showed that the eccentric shaft rises the dissolved oxygen concentration by 14% than the centric shaft at the maximum discharge. In addition, decreasing the enlargement angle from 270º to 220º increasing the amount of flow rate passing through the shaft by 18% and decreasing the water depths above the vortex channel by 29%.
Climate change, population growth and urbanisation are predicted to have a negative impact on catchments in the future. This is due to the increase in surface runoff volumes causing an increase in flood events. Some sections of existing sewer infrastructure may not have the capacity to convey the volumes of collected runoff and sewage without flooding or failure. Enlarging existing sewer infrastructure is typically unfeasible and above ground solutions (i.e. rainwater harvesting and SuDS) can be unpractical due to a lack of available surface area and low soil infiltration rates. This project aims to find a solution to increase the flood resistance of sewers where opportunities for sewer enlargement, rainwater harvesting and SuDS are limited. Customer Increase in the sewer system's level of flood resistance Solutions tailored to prioritise specific areas or objectives Reduction of CSO spills and pollution incidents Compliance Increase in the sewer system's level of flood resi...
Vortex Drop Shaft Structures: State-Of-The-Art and Future Trends
38th IAHR World Congress - "Water: Connecting the World"
Vortex drop shaft structures have played a critical role in hydraulic engineering; from one of their first applications in hydroelectric energy dissipation in the 1940s, to numerous contemporary installations throughout modern day urban drainage infrastructure. They are known to convey flows up to 1400 m 3 /s through drop heights of 190 m and due to their small footprint, stable flow mechanics and enhanced energy dissipation, they are often considered to be the most successful form of hydraulic drop structure. There are several design questions on various aspects of vortex drop shaft structures that have not yet been addressed in the laboratory environment or at full-scale and moreover will require full appreciation by engineering practitioners in future years. This article summarizes over 75 years of research and development of vortex drop shafts including types of structure, applications, laboratory modelling techniques, physical modelling studies and recent advancements in multiphase numerical modelling. The article discusses the hydraulics of various types of vortex drop shaft structures such as the key design differences between subcritical and supercritical intakes, energy dissipation, and aeration and presents the insights gained from successful case study commercial projects. The outcomes of seminal research studies and projects are discussed in detail and areas that are deemed to require further research and development are highlighted.
Hydraulic design aspects for supercritical flow in vortex drop shafts
Urban Water Journal, 2019
Vortex drop shafts, as special sewer manholes, operate optimally if an adequate energy dissipation is guaranteed and the integrity of the structural components is safeguarded. The results of an experimental study on a vortex drop shaft with supercritical inflow are discussed herein. The hydraulic behaviour of the spiral inlet, the vertical shaft and the dissipation chamber is described. Based on detailed flow observations, useful recommendations for designing these structures are provided. It is demonstrated that a relation adopted for supercritical bend flows provides a reliable estimation of the maximum wave height along the inlet. A procedure for predicting the rotational flow angles and the velocity distribution along vertical shafts with swirling flows is developed. Water levels and pressure measurements in the dissipation chamber are further analysed to identify maximum forces acting on the chamber invert and to derive preliminary design equations.
High Head Drop Shaft Structure for Small and Large Discharges
11th International Conference on Urban Drainage
In the early seventies, several high head drop structures were built as part of the construction of the Mexico City deep drainage system. The deep structures solved the problem of connecting the combined sewer system from street level to deep underground tunnels that enabled water discharges from urban areas. As it is common that the space available to build this type of structures is limited, the vertical drop may be several dozen meters, the discharges are extremely variable and it needs to function as sound- and vibration-free as possible; it is therefore necessary to carefully design, test in model and eventually build large drop shafts that take into account all of these conditions. Based on an Italian design (Drioli, 1947), a simpler drop shaft structure was proposed and tested in the late sixties for the Mexico City deep drainage system. It consisted of a spiral entrance that induces a strong vortical movement to achieve the adhesion of the water fall to the pipe walls for both small and large discharges. After more than 35 years of operation, the hydraulic behavior of this drop shaft has been satisfactory. As its characteristics and study results have never been published in English or in an international media, it was considered important to publish them and to highlight the advantages that this type of high head drop shaft has in terms of others found in specialized literature which can be more complicated and expensive.
Improvements in vortex flow control design to increase sewer network flood resistance
Flow controls are used within the water industry to manage the flow through sewer networks by attenuating flows at convenient or critical locations. Many sewer networks, regardless whether the systems have a flow control installed, are predicted to become stressed in the future due to the effects of climate change, population growth and urbanisation. This issue is compounded by the age of the Britain's sewerage infrastructure as well as the cost and difficulty of replacing and upgrading the infrastructure. Statutory 'Catchment Flood Management Plans' have been introduced within the United Kingdom to tackle this issue by better understanding the flow path of flood water on a catchment scale. This paper discusses a method to maximise the use of the current sewerage infrastructure by installing flow controls, meaning a greater volume of the sewer network can be used for stormwater storage. This paper continues by describing a method of increasing a sewer network's flood resistance by using vortex flow controls with a lower design flow-rate compared to an orifice plate. This paper then concludes by describing three case studies demonstrating the use vortex flow controls when retrofitting sewer networks as well as the impact of implementing the retrofit design method.
2015
The functionality of sewer networks is strongly affected by the correct operation of their appurtenances; the dendritic structure of urban drainage systems implies that junction manholes represent a crucial hydraulic structure, allowing two conduits merging into one. Hydraulic features of combining flows become quite complex when supercritical flows are involved, as in the case of steep urban context, with consequent formation of shockwaves and surging phenomena. Former studies conducted by Gisonni and Hager resulted in an optimized layout of sewer junctions operated under supercritical approach flow conditions. Recently, an extensive experimental campaign was performed on a physical model with generalized geometrical conditions, including various conduit diameters. Furthermore, physical model tests have been used to implement and validate a numerical model, aiming to explore a wider range of junction angles, which were limited to 45° and 90° for the physical model. In particular, t...