scholarly journals CFD Investigation of a High Head Francis Turbine at Speed No-Load Using Advanced URANS Models

2018 ◽  
Vol 8 (12) ◽  
pp. 2505 ◽  
Author(s):  
Jean Decaix ◽  
Vlad Hasmatuchi ◽  
Maximilian Titzschkau ◽  
Cécile Münch-Alligné
Keyword(s):  
Power Plants ◽  
Turbulence Modeling ◽  
Suction Side ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Hydroelectric Power ◽  
Electrical Grid ◽  
Runner Blade ◽  
Pumped Storage

Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, which reduces the lifespan of the machines. CFD based on standard URANS turbulence modeling is currently able to predict accurately the performances of the hydraulic turbines for operating points close to the Best Efficiency Point (BEP). However, far from the BEP, the standard URANS approach is less efficient to capture the dynamics of 3D flows. The current study focuses on a hydraulic turbine, which has been investigated at the BEP and at the Speed-No-Load (SNL) operating conditions. Several “advanced” URANS models such as the Scale-Adaptive Simulation (SAS) SST k - ω and the BSL- EARSM have been considered and compared with the SST k - ω model. The main conclusion of this study is that, at the SNL operating condition, the prediction of the topology and the dynamics of the flow on the suction side of the runner blade channels close to the trailing edge are influenced by the turbulence model.

Effect of Runner Blade Thickness on Flow Characteristics of a Francis Turbine Model at Low Flowrates

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Seung-Jun Kim ◽  
Young-Seok Choi ◽  
Yong Cho ◽  
Jong-Woong Choi ◽  
Jin-Hyuk Kim
Keyword(s):  
Stokes Equations ◽  
Guide Vane ◽  
Vortex Formation ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Hydroelectric Power ◽  
Runner Blade ◽  
Blade Thickness ◽  
Interblade Vortices

Abstract Francis turbines are often used for generating hydroelectric power, but their performance characteristics significantly depend on the operating conditions. In particular, interblade vortices in the passages between runner blades can occur at low flowrates, which can degrade performance, and increase vibrations and instability during operation. In a previous study, we showed that the hydraulic performance and flow characteristics depend on the flow passage area of runner blades under low-flowrate conditions. Under such operating conditions, the runner blade thickness can affect the interblade vortex characteristics, and in turn, affect the performance of the turbine. In this study, we investigated the effect of runner blade thicknesses in the presence of interblade vortices under low flowrates; steady- and unsteady-state Reynolds-averaged Navier–Stokes equations were solved using a shear stress transport as a turbulence model. The interblade vortices were described well at the near leading and trailing edges near the hub. These vortex regions showed flow separation and stagnation flow, and the interblade vortex characteristics were dependent on the high-magnitude unsteady pressures at the low-frequency region. For the same guide vane opening, at lower flowrates, higher blockage ratios reduced interblade vortex formation and unsteady pressure.

Numerical Investigation on Channel Vortex in a Francis Turbine

2011 ◽  
Author(s):  
Maojin Zhang ◽  
Shuhong Liu ◽  
Yulin Wu ◽  
Demin Liu ◽  
Lefu Zhang
Keyword(s):  
Guide Vane ◽  
Vortex Motion ◽  
Leading Edge ◽  
Suction Side ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Computational Domain ◽  
Flow Passage ◽  
Runner Blade ◽  
Steady Simulation

When a Francis hydraulic turbine operates under different working heads at small flow condition, the fluid in the flow passage will generate vortex shedding near the blade leading-edge and form the channel vortex in the blade passages due to the mismatch between the outlet angle of guide vane and the inlet angle of runner blade. The severity of channel vortex will trigger high-frequency vibration or generate unit resonant vibration, affecting the operational stability of the turbines. In this paper some typical operation points were chosen out for the steady simulation of a model turbine according to a unit hill-chart. The computational domain was chosen as the whole flow passage from the inlet of the volute to the outlet of the draft tube. Based on RNG k–ε turbulence model, the internal flows was simulated, and the occurrence of vortex between the turbine runner blades was discussed. The numerical results show that the vortex motion near the development-line (IVDL) is stronger than that near the channel vortex inception-line (IVIL) in channel vortex zone marked in the hill-chart. The velocity triangle is used to explain the reasons that channel vortex occur in the suction side at high working head while in the pressure side at the low working head, and two different forms and formation mechanism of the channel vortex were analyzed.

Measurement of Unsteady Flow in Pump-Turbine for Hydropower Using PIV Method

2009 ◽  
Author(s):  
Nobuhiko Fukuda ◽  
Satoshi Someya ◽  
Koji Okamoto
Keyword(s):  
Rotational Speed ◽  
Velocity Measurement ◽  
Numerical Procedure ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
High Time ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Runner Blade ◽  
Wide Range

It is thought that the pressure fluctuation can occur due to the interaction between flow through guide vanes and flow into runner blades, resulting in a vibration of turbine and a blade cracking, in a hydraulic turbine operated in a wide range for flexible power demand. High accurate velocity measurement with high time/spatial resolution can help to clarify the mechanism of the interaction and to provide good experimental data for the validation of numerical procedure. So the aim of present study is to estimate the unstable velocity field quantitatively in the area between guide vanes and runner blades, using high time-resolved particle image velocimetry (PIV). Two types of velocity measurements were carried out, i.e., phase-locked measurement and high time sequential velocity measurement, in a pump-turbine model with 20 guide vanes and 6 runner blades. The characteristic of the flow field varied corresponding to the operating conditions such as flow rate and rotational speed. Opening angles of guide vanes were kept uniform. A clockwise vortex was generated at inside of the runner blade under smaller rotational speed. A counterclockwise vortex was separated at the backside of the runner blade under higher rotational speed. At any operating conditions, the velocity between guide vanes and runner blades oscillated periodically at the blade passing frequency.

scholarly journals Numerical Study of Sediment Erosion Analysis in Francis Turbine

2019 ◽  
Vol 11 (5) ◽  
pp. 1423 ◽  
Author(s):  
Md Rakibuzzaman ◽  
Hyoung-Ho Kim ◽  
Kyungwuk Kim ◽  
Sang-Ho Suh ◽  
Kyung Kim
Keyword(s):  
Erosion Rate ◽  
Cavitation Erosion ◽  
Numerical Study ◽  
Leading Edge ◽  
Suction Side ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Trailing Edge ◽  
Sand Erosion ◽  
Turbine Design

Effective hydraulic turbine design prevents sediment and cavitation erosion from impacting the performance and reliability of the machine. Using computational fluid dynamics (CFD) techniques, this study investigated the performance characteristics of sediment and cavitation erosion on a hydraulic Francis turbine by ANSYS-CFX software. For the erosion rate calculation, the particle trajectory Tabakoff–Grant erosion model was used. To predict the cavitation characteristics, the study’s source term for interphase mass transfer was the Rayleigh–Plesset cavitation model. The experimental data acquired by this study were used to validate the existing evaluations of the Francis turbine. Hydraulic results revealed that the maximum difference was only 0.958% compared with the CFD data, and 0.547% compared with the experiment (Korea Institute of Machinery and Materials (KIMM)). The turbine blade region was affected by the erosion rate at the trailing edge because of their high velocity. Furthermore, in the cavitation–erosion simulation, it was observed that abrasion propagation began from the pressure side of the leading edge and continued along to the trailing edge of the runner. Additionally, as sediment flow rates grew within the area of the attached cavitation, they increased from the trailing edge at the suction side, and efficiency was reduced. Cavitation–sand erosion results then revealed a higher erosion rate than of those of the sand erosion condition.

scholarly journals Manipulation of the swirling flow instability in hydraulic turbine diffuser by different methods of water injection

2018 ◽  
Vol 180 ◽  
pp. 02090 ◽  
Author(s):  
Pavel Rudolf ◽  
Jiří Litera ◽  
Germán Alejandro Ibarra Bolanos ◽  
David Štefan
Keyword(s):  
Swirling Flow ◽  
Flow Instability ◽  
Draft Tube ◽  
Water Injection ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Necessary Condition ◽  
Vortex Rope ◽  
Wide Range

Vortex rope, which induces substantial pressure pulsations, arises in the draft tube (diffuser) of Francis turbine for off-design operating conditions. Present paper focuses on mitigation of those pulsations using active water jet injection control. Several modifications of the original Susan-Resiga’s idea were proposed. All modifications are driven by manipulation of the shear layer region, which is believed to play important role in swirling flow instability. While some of the methods provide results close to the original one, none of them works in such a wide range. Series of numerical experiments support the idea that the necessary condition for vortex rope pulsation mitigation is increasing the fluid momentum along the draft tube axis.

Design of a Francis Turbine for a Small Hydro Power Project in Turkey

2010 ◽  
Author(s):  
Kutay Celebioglu ◽  
Gizem Okyay ◽  
Mehmet Yildiz
Keyword(s):  
Power Plants ◽  
Parametric Design ◽  
Optimization Procedure ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Design Parameters ◽  
Hydro Power ◽  
Total Potential ◽  
Computational Fluid Dynamics Analysis ◽  
Hydro Power Plants

Many hydro power plants, both in small and large scales, are being constructed in Turkey. The total potential of these projects reach to 216 billion kWh of feasible energy. However a method was not yet developed for the design of hydraulic machinery equipment in Turkey. In order to accomplish the hydraulic turbine design without any prior information than the design parameters of the hydraulic project, a methodology is developed. This methodology involves the use of computational tools and it is applied for small hydro projects. This methodology is a parametric design-optimization procedure which consists of parametric geometry modeling, computational fluid dynamics analysis and structural verification.

THE INFLUENCE OF OPERATION CONDITIONS OF HYDROELECTRIC POWER PLANTS THE CHOICE OF THE MAIN PARAMETERS OF THE SUCTION PIPES

2015 ◽  
Vol 5 (4) ◽  
pp. 86-92 ◽  
Author(s):  
Mikhail Ivanovich BALZANNIKOV
Keyword(s):  
Power Plants ◽  
Draft Tube ◽  
Operating Conditions ◽  
Hydroelectric Power Station ◽  
Geometrical Parameters ◽  
Hydroelectric Power ◽  
Operation Conditions ◽  
Hydropower Plants ◽  
Large Water ◽  
Run Of River

Considered run-of-river hydropower plants (HPP). Notes the importance of technical-economic calculations in the justifi cation of large water-conducting elements of the path these types of HPP. The methodology of economic substantiation of the expediency of increasing the length of the draft tube. Using the technique of the calculations for lowpressure hydroelectric run-of-river type. The results of the analysis of the influence of the operating conditions of the hydroelectric power station on basic geometrical parameters of draft tube.

scholarly journals SAVING RESOURCES IN THE CONSTRUCTION OF HYDROELECTRIC POWER PLANTS

2019 ◽  
Vol 1 ◽  
pp. 20
Author(s):  
Mikhail Balzannikov
Keyword(s):  
Power Plant ◽  
Peak Power ◽  
Power Plants ◽  
Hydroelectric Power Plant ◽  
Operating Conditions ◽  
Hydroelectric Power ◽  
Construction Work ◽  
Construction Costs ◽  
Suction Pipe ◽  
Hydroelectric Power Plants

The article describes run-of-the-river hydroelectric power plants. The authors specify the importance of performing technical and economic calculations in justifying the large-sized units of the water-supplying channel of a run-of-the-river hydroelectric power plant: turbine pits and suction (discharge) pipes. The study shows that the amount of construction work and the total cost of building a hydroelectric power plant depend on the size of these water supply units. The research objective is to analyze the validity of establishing the main dimensions of the suction pipes for modern technical and economic conditions. The researchers use the discounted income method. The calculations are performed for a hydroelectric power plant with an elbow suction pipe. The analysis of how the operating conditions of a hydroelectric power plant influence the savings of construction resources is carried out. The analysis shows that saving construction resources by reducing the length of the suction pipe is justified if the hydroelectric power plamt is designed to work only at peak power loads. For hydroelectric power plants operating at semi-peak or base power loads, the additional construction costs would be appropriate if leading to the decrease in pressure loss and to the increase in electricity generation.

scholarly journals Methodology for substantiation of technical and economic indicators of PSPP in energy water management systems of Uzbekistan

2021 ◽  
Vol 264 ◽  
pp. 04056
Author(s):  
Muradilla Mukhammadiev ◽  
Kurbon Dzhuraev ◽  
Sanjar Juraev ◽  
Abdurauf Abduaziz Uulu ◽  
A Makhmudov
Keyword(s):  
Water Management ◽  
Economic Efficiency ◽  
Power Plants ◽  
Economic Indicators ◽  
Management Systems ◽  
Hydroelectric Power ◽  
Hydroelectric Power Plants ◽  
The Republic ◽  
Pumped Storage ◽  
Technical And Economic Indicators

In our country, a lot of attention is paid to the development of the energy sector. A lot of work is underway to modernize existing capacities and commission new capacities. At the same time, the unit capacities of units and power plants also increase, which ensures faster commissioning of capacities in the power system and an increase in the efficiency of power plants. Attention is also paid to the development of power plants based on renewable energy sources (hydraulic, solar, wind, etc.). One of the most important tasks in the power industry is to cover peak minimum and maximum loads, which is becoming increasingly important in connection with the growth of the power system's capacity. As is known, according to world indicators, the maneuverable capacities should be about 25% of the total power of the EPS. The most promising maneuverable capacities are hydroelectric power plants. However, in our country, hydroelectric power plants account for about 14.3%. This task will become more complicated with the introduction of capacities based on solar and wind energy and the commissioning of new hydroelectric and thermal power plants in the Republic. This is because RES capacities have a significant discontinuity even during the day, and the water resources in the Republic are primarily for irrigation and drainage purposes and are significantly variable during the season. One way to solve these problems in the world is the creation and use of pumped storage power plants (PSPP). The peculiarities of the creation and use of pumped storage power plants in our region are that the available hydro resources of our region are mainly of water management importance, while the task is also to increase the energy efficiency of existing reservoirs. Based on the foregoing, we can say that the development of methods for determining the economic efficiency of pumped storage power plants, taking into account direct and indirect effects, taking into account the peculiarities of their use in energy and water management systems of Uzbekistan is the main task for the present time. To solve the set tasks, a new methodology and program for substantiating the technical and economic indicators of pumped storage power plants in Uzbekistan's energy and water management systems have been developed. The schemes of using pumped storage power plants at four energy and water management facilities, that is, the Tuyamuyun hydro subunit, Arnasai, Talimarjan, and Khodjikent reservoirs, were considered, and for these facilities, based on the developed methodology and program, their technical and economic parameters of the pumped storage power plant were determined. Based on the results obtained, it can be said that using the PSPP in four facilities, it is possible to generate a total of about 418 MW of capacity and more than 930.0 million kWh of electricity, as well as to save 139 thousand tons of fuel equivalent per year, with this, the annual economic efficiency will be about 700.0 billion sums.

Analysis of Inner Flow Inside Francis Turbine Runner Based on Dissipation Function

2008 ◽  
Author(s):  
Xiaojing Wu ◽  
Yulin Wu ◽  
Shuhong Liu
Keyword(s):  
Energy Loss ◽  
Flow Simulation ◽  
Dissipation Function ◽  
Operating Conditions ◽  
Surface Strain ◽  
Francis Turbine ◽  
Dominant Factor ◽  
Flow Energy ◽  
Runner Blade ◽  
Turbine Runner

Energy loss inside a Francis turbine runner is analyzed with dissipation function in this paper. The dissipation rate of a Newtonian flow with constant shear viscous has three constituents from dilation, vorticity, and surface strain, which is derived from kinetic energy equation presented in this paper. A commercial N-S equation solver has been employed for 3D turbulent flow simulation with a model Francis turbine, and three different operating conditions are chosen for comparison, which are part load, rated load, and excessive load. The results from simulation have been compared with model experiments to validate their preciseness and reliability. The distribution of dissipation constituents on runner blade surface have been extracted from the above simulation results. The distinction of these constituents can be used to identify flow structures inside runner. The flow energy loss is determined by dissipation function, thus it can affect the hydraulic efficiency of turbine runner. From the above results, it can be seen that what causes the energy loss, which is the dominant factor, and where it has the highest value. Thus this analysis based on dissipation function can be used for flow diagnosis inside the blade channel, and tell us which part of the blade should be improved to reduce the energy loss.

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