Sediment Control At The Lateral Channel Inlet

Environmental and civil engineering projects frequently employ the open channel side intake structure. However, the commonest among the issues faced in most of the lateral intakes include sedimentation and sediment delivery. This involves several problems namely, decreased flow discharge capacity in the irrigation canals and the threat of water blockage during times of low water flow. Besides, this problem with the sediment either lowers the performance levels or causes failure of the facilities that this sub-channel serves. Hence, the engineers focused on designing an intake with the features of high flow discharge and low sediment delivery. This paper attempts to review and summarize the literature relevant to the branching channel flow and submerged vane technique to minimize the sediment-related issues. The present review highlights that most of the earlier research work done dealt with the characteristics of the flow in a right-angle branch channel possessing rigid confines. Also, more investigations are required regarding the implications of the submerged vanes. Besides, no comprehensive studies are available on the saddle point itself, and a high percentage of the studies have been part of earlier investigations that had focused on only briefly outlining this subject.

Assessment of the effect of shapes of a shaft intake structure using the PIV method

The construction of shaft intake structures in Slovakia has increased. The shaft intake structures overcome significant vertical height over short horizontal distance. In their front horizontal section, the water flows with free surface, then in the vertical section the flow changes its direction and character to a pressurized flow. The flow of water in these shaft intake structures is therefore very complicated. A hydraulically suitable design of the intake structure is associated with achieving the required parameters of the small hydropower plant (SHPP), but due to the reduction of project costs, the shapes of shaft intake structures of SHPP are often not correctly hydraulically designed. One of the important aspects is the distribution of flow velocity of these intake structures. Uneven distribution of flow velocity causes negative effects on turbine performance. Therefore, the investigation of the effects of shaft intake structure design on flow velocity distribution has been realized. The velocity field at a shaft intake of a small hydropower plant was investigated on a physical model in a hydraulic laboratory using the PIV (Particle Image Velocimetry) method. The PIV measurements were realized for different shaft heights and proved negative effects of the design on the flow homogeneity in the turbine intake.

Experimental Investigation of 900 Intake Flow Patterns with and without Submerged Vanes under Sediment Feeding Conditions

In this study, two experiments were conducted in a 90⁰ water intake to study 3D flow patterns and sediment distribution using submerged vanes under sediment feeding and live-bed conditions. One column three vanes were installed at a 20⁰ angle maintaining for a water discharge ratio of q_r ~ 0.1. Three-dimensional mean and turbulent velocity components of flow in 90⁰ channel intake were measured by Acoustic Doppler Velocimetry (ADV). Flow characteristics of the intake structure area with no vanes are compared with those condition. Results showed that three vanes with single column reduced the amount of sediment by 20% in the intake diversion. In the downstream corner of the intake, high velocities were measured where scouring occurred. The vanes affected the intensity of secondary flow, turbulence energy, flow separation, and moved sediment deposition downstream of the main channel.

Evaluation of the flow velocity distribution in the intake structure of a small hydropower plant

Intake structures are an important part of small hydropower plants, which affect the water flow, turbine operation and total power of power plant. The flow quality is significantly influenced by the flow homogeneity in the intakes, as the inhomogeneous flow velocity distribution has a negative impact to the operation of the hydropower plants, such as uneven load on the mechanical parts which leads to decrease in efficiency and faster aging of turbine parts. The paper describes the flow assessment in the intake structures of a low-pressure small hydropower plant (the Stará Ľubovňa small hydropower plant) with respect to the flow homogeneity. The River2D, 2D numerical modelling software, has been used for evaluation of flow in the intakes. Flow simulations for the current state of operation have been modelled. In assessing the current situation of intake structure, scenarios were modelled. The boundary conditions were changed to approximate the various variants of hydropower plant operation. The simulations proved the negative impact of the construction solution for the flow conditions in the intakes. This appears mostly in profiles of coarse racks and screenings where is a significant unequal distribution of flow and significant deviation in flow velocities from the recommended values. The simulations results were evaluated in turbine intake profiles (profile of screenings), where the distribution of flow velocities was evaluated. The flow velocities in this profile were compared with the average flow velocity in the turbine intake profile. In order to optimize the velocity distribution in the intake structure, the modification of the intake shapes has been proposed. The subject of the proposal was to improve flow parameters. Simulations were created for the modification that were subsequently reviewed. The modification was compared to the current situation of the intakes.

DEVELOPMENT OF A FICH PROTECTION DEVICE DESIGN

The water intake structure is a functional element of the water supply system, but it must also be a fish protection object. The following basic requirements are imposed on the devices of modern fish protection devices at water intakes: prevention of ingress and death of young fish and larvae, prevention of injury to young fish and larvae, removal of protected fish from water intake, reliability of operation under specific conditions and means. According to the principle of operation, the most effective is the active scheme, with the forced formation of the hydraulic flow structure. The design of a universal combined type device with the use of a jet generator as a flow-forming element that creates a reactive hydraulic movement designed to protect fish and juveniles with a body size of less than 15 mm is proposed.

Numerical Investigation of the Performance of a Submersible Pump: Prediction of Recirculation, Vortex Formation, and Swirl Resulting from Off-Design Operating Conditions

Like any other turbomachinery, it is essential that the hydraulic behavior and performance of mixed-flow pumps are evaluated way in advance prior to manufacturing. Pump performance relies heavily on the proper design of the intake structure. Intake structures should be accurately designed in order to minimize and avoid unnecessary swirl and vortex formations. Ensuring the optimum performance condition as well as predicting how a particular intake structure affects the efficiency of the pump often requires either physical model studies or theoretical evaluations. Unfortunately, physical models are costly, time-consuming, and site-specific. Conversely, design and performance predictions using a theoretical approach merely gives performance values or parameters, which are usually unable to determine the root cause of poor pump performance. This study evaluates the viability of using Computational Fluid Dynamics (CFD) as an alternative tool for pump designers and engineers in evaluating pump performance. A procedure for conducting CFD simulations to verify pump characteristics such as head, efficiency, and flow as an aid for preliminary pump design is presented. Afterwards, a multiphase simulation using the VOF approach is applied to compare the fluid dynamics between four different pump intake structures. A full-sized CFD model of the pump sump complete with the pump’s active components was used for the intake structure analysis in order to avoid scaling issues encountered during the reduced-scale physical model test. The results provided a clear illustration of the hydraulic phenomena and characteristic curves of the pump. A performance drop in terms of reduction in TDH was predicted across the various intake structure designs. The CFD simulation of intake structure provided a clear insight on the varying degree of swirl, flow circulation, and effect on pump efficiency between all four cases.

Downstream Fish Passage at Hanover Pond Dam Through the Use of an Archimedes Screw Generator

Background: In 2016, an Archimedes Screw Generator (ASG) was installed at the Hanover Pond Dam located in Meriden, CT on the Quinnipiac River to support hydroelectric operations for New England Hydropower Company, LLC (NEHC). The ASG is the first of its kind implemented in the United States, and while they are largely described as ‘fish-friendly’, adequate scientific literature evaluating fish passage is lacking at these facilities. The Connecticut Department of Energy and Environmental Protection (CT DEEP) with consultation from U.S. Fish and Wildlife Service (USFWS) and Kleinschmidt Associates designed and implemented a study to evaluate American Shad downstream fish passage at Hanover Pond Dam. The objective of this study was to document whether American Shad would enter the darkened penstock, pass beneath the downward closing sluice gate, and utilize the ASG for safe downstream passage. A radio telemetry study was designed with three fixed monitoring stations; including one station upstream of the dam, another station within the intake structure, and a third station downstream of the dam. Twenty adult American Shad were collected from Holyoke Dam Fish lift, transported to Hanover Pond, and radio-tagged. Fish were released upstream of the dam and monitored from May 30 to July 15, 2019.Results: In total, 16 fish were detected upstream of the dam, and 8 of those fish passed downstream. Seven of the eight fish that passed through the project (87.5%) utilized the intake of the ASG before being detected at the downstream receiver. One fish passed downstream via the spillway and/or use of a notch in the dam. All fish that passed downstream were detected with subsequent 2-second tag bursts at the downstream monitoring station, suggesting a 100% survival rate through the ASG.Conclusions: These results support the suggestion that the Archimedes Screw Generator is a ‘fish friendly’ operation.

THE FORMATION MECHANISMS OF COMPOSITION OF DRINKING GROUNDWATER OF THE Kyiv DEPOSIT (ON THE EXAMPLE OF THE OBOLON WATER INTAKE STRUCTURE)

This paper presents the results of the assessment of interactions in the water-rock system using an integrated approach including the balance method and the method of geochemical (thermodynamic) modelling. Assessment is carried out for conditions of Cenomanian-Callovian and Bajocian aquifers within the Obolon groundwater intake structure in Kyiv. The results obtained demonstrate that groundwater of the Cenomanian-Callovian and Bajocian aquifers within the Obolon groundwater intake structure differ in chemical composition, physicochemical conditions, and especially in the formation of water composition due to the interactions in the water-rock system. This paper proposes division of water into groups, taking into account both the features of chemical composition and its formation process. The water group characterized by anomalous ratio of chlorine and sodium is distinguished, as well as the possible formation mechanism of this water composition is proposed. The chemical composition of the waters of both aquifers meets the requirements of Ukrainian legislation for drinking water quality (GSanPiN 2.2.4-171-10). Groundwater quality of the Cenomanian-Callovian complex is shown to be higher than that of the Bajocian aquifer. For both aquifers, the water of higher quality is the one with cationic composition determined largely by ion exchange. The ion exchange processes can be controlled to a certain extent by regulating the water withdrawal from the wells, and hence the water quality can be regulated in this way as well. Another way to regulate water quality could be the mixing of water from two aquifers during water treatment, which would, on the one hand, compensate the insufficient water quality of individual aquifers and, on the other hand, provide for continuous well operation contributing to the maintenance of more or less stable physicochemical processes. However, these hypotheses require further detailed consideration and, if confirmed, a detailed justification of their feasibility.

Analyzing the impact of intake structure on the flow at low pressure SHPP

The structural parts of intake structures directly affect the flow velocity distribution in the turbine intake of small hydropower plants, where inhomogeneous flow leads to uneven load of the turbine units causing operational problems. A 2D numerical flow modeling was used for investigations of the flow in an intake structure of a low-head small hydropower plant. The effects of shape changes of the intake structure on the flow velocity distribution in the turbine intakes were investigated and assessed proving significant effect of the shapes of the intake structure on the flow homogeneity in turbine intakes.