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The present work focuses on the evaluation, by best efficient point (BEP), Nash–Sutcliffe efficiency (NSE), mean square relative error (MSRE), relative mean error (RME) and residual bias (BIAS) of a prototype of a gravitational water vortex turbine. The analysis performed using computational fluid dynamics was experimentally validated to quantify the accuracy of the mathematical model. The estimation of the statistical parameters mentioned was made for different response variables, such as vortex height H v , torque T s , mechanical power P m and efficiency η t , in order to identify biases in different areas of the simulation. The BEP was determined for a flow rate of 6.0 l / s with an efficiency of 58.13% in the experimental part and 54.62% in the numerical modeling, with the vortex height as the critical parameter of the system due to its influence on performance. The NSE and MSRE indicators were positioned as the functions with the best adaptability for the response parameters by criteria and sensitivity. Meanwhile, the RME, MSRE and BIAS presented significant differences for the values of mechanical power and torque. Regarding the electrical efficiency of the generator, it was estimated at 27.68% for the BEP with an average decrease of 3.1% per unit of flow supplied from this point. Therefore, the turbine is subject to the conditions of the generator (torque and number of revolutions per minute) and vortex height, which control the optimization of the system. [ABSTRACT FROM AUTHOR]

A specific example demonstrates the aspects of transient processes in hydropower plants with double-regulated turbines. To prevent malfunctioning of the unit blocks of hydropower plants, such as unit throwing up, recommendations are provided on the choice of modes of movement of the regulating unit to reduce the negative axial forces acting on the turbine impeller. [ABSTRACT FROM AUTHOR]

The fatigue failure problem of parts of a hydraulic turbine after a long service life is considered. State analysis of elements of hydraulic power equipment and a method for assessing the residual resource of a part in the presence of cracking are presented. The assessment problem of reliability of operation and extending the service life of equipment is discussed. [ABSTRACT FROM AUTHOR]

The article presents information on technical situations during the commissioning of the technological equipment for a hydropower plant (HPP). [ABSTRACT FROM AUTHOR]

The article presents an analysis of the experience of conducting field power tests of hydraulic units with the measurement of water flow rate by different methods at a number of domestic and foreign dam-type hydropower plants. [ABSTRACT FROM AUTHOR]

Technical situations, including accidents, during construction, installation, operation, and retrofitting of the process equipment of HPP are described. [ABSTRACT FROM AUTHOR]

A technique is proposed for generating the set of surfaces of a toroidal draft tube of a hydraulic turbine depending on 19 geometric parameters and for constructing grids in the area of the tube to search for the optimal shape based on numerical simulation of flows. [ABSTRACT FROM AUTHOR]

The article describes the introduction of a more modern linear electromechanical drive instead of a hydraulic drive into the hydraulic unit control system at Russian HPPs/PSPs. A comparative analysis of these types of drives and the regulatory requirements for their use in the state standards of the Russian Federation and RusHydro standards are given. The objectives of the planned work are outlined. [ABSTRACT FROM AUTHOR]

The role that hydropower plays in the world's energy balance is considered, and a comparative analysis of using hydropower resources in Russia and abroad is presented. It is shown that Russia occupies the world's second place in its hydropower potential after China; however, no more than 20% of the country's hydraulic power resources have presently been harnessed. This is significantly lower than in Germany, France, Sweden, and Japan, countries in which 65–90% of their available hydraulic power resources are used. In view of a great variety of natural conditions, turbines of different types are used in the hydraulic power industry. It has been determined that the power performance indicators (efficiency and capacity) of the hydraulic machines that are presently produced in Russia correspond, as in the years of the former Soviet Union, to world-class standards. Trends in the development of hydropower and construction of hydraulic turbines are analyzed. It is shown that, given insignificant scales of constructing new hydroelectric power plants in Russia, replacement of the equipment at the existing hydroelectric power plants that had worked out its standard service life long ago is the industry's main development line for the nearest (10–15 years) future. The need to replace the operating hydraulic machines mainly stems from inefficient utilization of water stream at the existing hydroelectric power plants. It is pointed out that, despite the emerged tendency toward decreasing the reliability of hydraulic power units that have been in operation for a long period of time, its catastrophic drop is not observed at any of the examined hydroelectric power plants even though their machines have been in operation for twice as much as their standard service life (30 years) or even more. Refurbishment of the machines makes it possible and shall mandatorily improve the power performance characteristics of the machines, resulting in an increased power capacity or improved efficiency (of energy generation). An improvement in the power performance characteristics of new hydraulic turbines is achieved almost solely due to the use of more advanced runners while keeping the other flow path elements unchanged. [ABSTRACT FROM AUTHOR]

Nowadays, developments in the field of combined power units represent an urgent task for energy supply to consumers. One of the promising directions in this field consists in the development of engineering solutions based on low head pressure (ΔZ ≤ 20 m) microhydroelectric power plants with a siphon penstock, using the terrain features, natural reservoirs with height differences, and a ready industrial infrastructure. One of the specific problems of such combined power units consists in the operation of hydraulic turbines at variable head pressure, which leads to inconsistencies in the generation of electrical energy and a significant idle time in the hydraulic unit's operation. In this paper, possible solutions to this problem are considered that are associated with the use of hydraulic turbines having an aperiodic blade system designed for the entire design domain of feeds Q and heads H determined from the conditions of joint operation of the hydraulic system–hydraulic turbine complex at different ΔZ. To carry out parametric studies, a design model for the hydraulic part of the cogeneration system has been developed, including a fragment of a siphon penstock and a hydraulic turbine. Studies on the grid viscosity and calculation and experimental verification of the model have been performed and optimal settings for the grid generator and the number of cells have been established: nel = 1 300 000 elements. The optimal settings have been obtained based on achieving an averaged value in calculated and experimental hydroturbine power δN accurate within ±5%. The numerical simulation of several variants for hydraulic turbines with different blade systems designed taking into account the experience of developing aperiodic blade systems in the field of pump engineering has been performed. In particular, such factors affecting the turbine efficiency as the pitch of the blade system at the inlet, outlet, and at the center of the skeletal lines of the blades, as well as the order of the blade arrangement in the aperiodic blade system, have been considered. A comparative analysis of hydraulic turbines with classical and aperiodic blade systems has been performed. It has been established that designing a bladed system of a hydraulic turbine in the design domain makes it possible to increase the efficiency of microHPP operation by 5.5% as well as to extend the range of efficient operation in the feed and head by 21.2 and 7.3%, respectively. At the same time, it should be noted that a low sensitivity of the main target parameter (efficiency of microHPP) with respect to the factors revealed in the course of the study is observed. Based on this, further prospects for the development of this study consist in the development of a parametric design model for a hydraulic turbine with the aperiodic blade system and a series of calculations using the theory of experimental design or stochastic methods for multidimensional optimization. [ABSTRACT FROM AUTHOR]

Inadequate efficiency with which the energy of water flow is used is the basic reason why it is necessary to reconstruct hydraulic turbine equipment with lengthy service life. Hydraulic turbines constructed in the Soviet period are characterized by high reliability indicators even after 50 – 60 years of service, i.e., the age of hydraulic units does not play a decisive role in reducing the reliability of equipment. [ABSTRACT FROM AUTHOR]

The authors have performed numerical simulation of pressure pulsations in the draft tube of a hydraulic turbine that are excited by large-scale vortex structures. Numerical simulation of unsteady transfer in the draft tube in different operating regimes of the turbine has been carried out. It has been shown that the structure of flow in the outlet diffuser corresponds to vortex-core flow. Calculated data have been compared with experimental results and their agreement has been shown. To suppress pressure pulsations, a study has been made of the influence of various structural inserts into the draft tube, such as fins, a cross piece, and a hollow cylinder in the draft-tube cone. Consideration has been given to the influence of various constructions on the structure of flow behind the wheel and on pressure pulsations on the draft-tube wall. A comparison has been made of the constructions and optimum parameters have been selected to stabilize the flow in the diffuser of the hydraulic-turbine draft tube. [ABSTRACT FROM AUTHOR]

Inadequate efficiency with which the energy of water flow is used is the basic reason why it is necessary to reconstruct hydraulic turbine equipment with lengthy service life. Hydraulic turbines constructed in the Soviet period are characterized by high reliability indicators even after 50 – 60 years of service, i.e., the age of hydraulic units does not play a decisive role in reducing the reliability of equipment. [ABSTRACT FROM AUTHOR]

Deep neural networks (DNNs) for intelligent machinery fault diagnosis require a large amount of training data, powerful computational facilities and have many hyper-parameters that have to be carefully tuned to ensure maximum performance. Deep forest, as a novel alternative to the deep learning framework, has the potential to overcome these shortcomings. In this study, a deep forest-based end-to-end intelligent fault diagnosis method is proposed for hydraulic turbine, in which multi-grained scanning is first used to transform fault feature representations from raw data and enhance fault feature learning ability, and then cascade structure is constructed with different types of random forests to learn fault features level by level and classify faults. The effectiveness of the proposed method is validated using the experimental dataset under twelve conditions, and its practicability is validated using a simulated dataset generated by adding white Gaussian noise to raw experimental signals. The results show that the proposed method is able to adaptively mine available fault features from measured signals, and its diagnosis accuracy is better than that obtained by existing methods. More importantly, the proposed method has better robustness to noise and is less limited to the number of training data. [ABSTRACT FROM AUTHOR]

Modern approaches, international trends and accumulated experience from the design of new power equipment for comprehensive modernization of the Votkinsk Hydroelectric Power Plant, a plant which has operated beyond its service life, are presented. [ABSTRACT FROM AUTHOR]

The determination of the energy characteristics of a Kaplan hydraulic turbine is based on numerous measuring points during extensive and expensive experimental model tests in laboratory and on-site prototype tests at the hydropower plant. The results of those experimental researches are valuable insofar as they are detailed and comprehensive. In order to reduce the number of modes, in which the double-regulated turbine has to be tested with the aim of obtaining the off-cam energy characteristics in unknown operating modes, the application of contemporary artificial neural networks models is presented in the paper. The rationalization of the turbine test conditions may not be at the expense of the quality of the obtained characteristics. Two types of neural networks, feedforward neural networks and adaptive network-based fuzzy inference system with different partitioning methods, were used. The reliability of applied method was considered by analyzing and validating the predicted turbine energy parameters with the results obtained in the highly sophisticated laboratory. [ABSTRACT FROM AUTHOR]

Information on technical events occurring in the course of running in operations, functional operations, and field tests and redevelopment of the process equipment of hydroelectric power plants that have occurred in Russia and abroad on domestically produced equipment and equipment produced abroad is discussed. [ABSTRACT FROM AUTHOR]

Some methods are proposed for geometric simulation of surfaces of the smooth spiral case and generation of the meshes for numerical simulation of flow. [ABSTRACT FROM AUTHOR]

Questions related to the use of large hydroelectric units functioning in underground hydroelectric power plants with the use of single- and dual-delivery scrolls with engine room of limited width and ceiling of its arch of sufficient strength are considered. [ABSTRACT FROM AUTHOR]

Some methods are developed for generating a set of surfaces of the smooth hydroturbine draft tube depending on the nine geometric parameters, and also for constructing meshes in the region of the draft tube for the subsequent optimization of its shape based on numerical simulation of flows. [ABSTRACT FROM AUTHOR]

The condition of the hydraulic turbines with service life (30 years) expired long ago still operating at the Verkhnyaya Tuloma HPP is described. Parameters of the new hydraulic turbine that provides more efficient use of water flow at the HPP and improves the reliability of equipment are proposed. [ABSTRACT FROM AUTHOR]

This paper presents a study of the movement and the hydrodynamic performance of a new tide-powered hydraulic turbine through numerical simulations. By means of the moving mesh method, the open-closed sequences of the blades and the movement of the rotors are obtained and the angular velocity and the average energy utilization coefficient under different tip speed ratios are also obtained. Moreover, the optimum tip speed ratio is identified by integrating the output power and the energy utilization coefficient of the hydraulic turbine with different tip speed ratios, providing data support for the prototype design of the hydraulic turbine. [ABSTRACT FROM AUTHOR]

In this paper, Unsteady RANS (URANS) simulations and Large Eddy Simulations (LES) in the draft tube of a bulb turbine are presented with the objective to understand and locate the head losses in this turbine component. Three operating points of the turbine are considered. Numerical results are compared with experimental velocity measurements for validation. Thanks to a detailed analysis of the energy balance in the draft tube, the physical and hydrodynamic phenomena responsible for head losses in the draft tube are identified. Head losses are due to transfer of mean kinetic energy to the turbulent flow and viscous dissipation of kinetic energy. This occurs mainly in the central vortex structure and next to the walls in the draft tube. Head losses prediction is found to be dependent on the turbulence model used in the simulations, especially in URANS simulations. Using this analysis, the evolution of head losses between the three operating points is understood. [ABSTRACT FROM AUTHOR]

Modern approaches, international trends and accumulated experience from the design of new power equipment for comprehensive modernization of the Votkinsk Hydroelectric Power Plant, a plant which has operated beyond its service life, are presented. [ABSTRACT FROM AUTHOR]

The question of the optimal shape of a hydraulic turbine blade is the chief issue in hydraulic turbine construction. It is necessary to design and create a sample of a turbine impeller with maximum efficiency and high cavitation properties. In order to achieve this objective, studies are conducted that are based on hydrodynamic analysis of the hydraulic turbine water path and selection of the best turbine blade geometry, by bringing in methods of genetic optimization. The author of this article proposes a different method of creating a turbine impeller: adding additional blade-splitters to the design. [ABSTRACT FROM AUTHOR]

Results are presented of experiments carried out using an air model of a hydraulic turbine draft tube. These included velocity measurements in the conical part of the tube using a laser-Doppler anemometer and measurement of pressure pulsations using acoustic sensors (microphones). It is shown that a system of two runner vane cascades can be used to simulate a velocity distribution that resembles the distributions downstream of a runner under full-scale conditions. Experiments show that modes involving the formation of a vortex rope occur in the region of significant hydroelectric generating unit underload. Analysis of spectra, the cross-correlation function, and mean velocity distributions confirmed the vortex nature of the generation of powerful pressure pulsations in the draft tube cone. [ABSTRACT FROM AUTHOR]

Many experiments have proven that with increasing silt and gas (out-of-phase media) content in water, the cavitation characteristics change and the cavitation pressure increases. Currently, many large reservoirs in China are polluted by total phosphorus (TP) and other chemical contaminants because of the use of phosphate fertilizer runoff from agriculture. However, research regarding how chemical pollutants (in the form of out-of-phase media) affect the cavitation pressure characteristics of water is sparse. In this paper, the Goupitan Hydropower Station, the largest hydropower reservoir on the Wujiang River, which is heavily polluted by TP, is taken as an example to evaluate the effects of chemical pollution on water cavitation pressure characteristics. In this study, the cavitation pressure characteristics of polluted and clean water are compared. The results show that the cavitation pressure of water polluted by chemicals is larger than that of clean water. In a hydraulic power generation system, cavitation and cavitation erosion are likely to occur earlier in runners when the fluid is polluted. These results are of great importance to further studies of cavitation theory and can directly influence the arrangement of turbines in practical engineering. [ABSTRACT FROM AUTHOR]

Anumerical procedure is presented for analysis of pressure pulsations in hydraulic turbines. Results of its use for description of unsteady turbulent flow in the continuous run of a hydraulic turbine are presented. The numerical method is adapted for results of modeling of turbulent unsteady flow in the continuous rune of a high-head HPP. The structure of the flow beyond the impeller and its effect on the intensity of unsteady processes are examined. Results of the analysis are compared with full-scale data. Good agreement is obtained between the computed and experimental results. [ABSTRACT FROM AUTHOR]

Different approaches to problems associated with evaluation of the strength and service life of hydraulic turbines with service lives exceeding the period assigned by the manufacturer are compared. Significant differences in approaches to strength evaluation in the design, construction, and modernization stages, and during an extension in service life are cited. Acomplex approach permitting establishment of a valid prediction of the behavior of a hydraulic turbine during an extended period of operation is proposed for assessment of remaining service life. [ABSTRACT FROM AUTHOR]

Technical and organizational requirements for remaining-life assessment of metallic structures of the water-delivery run of hydraulic turbines at HPP are examined. The remaining service life of a structural component should be evaluated with consideration of its actual technical condition. [ABSTRACT FROM AUTHOR]

We have investigated the effect of water compressibility on the nonstationary characteristics of turbines connected with the ability of the liquid to execute natural hydroacoustic vibrations in the setting of hydroelectric units. We have constructed a model of the setting up of forced hydroacoustic vibrations in the water conduit due to the precession of the vortex core running off the turbine. The conditions for the possibility that low-frequency hydroacoustic natural vibrations will arise have been considered. [ABSTRACT FROM AUTHOR]

In recent years, numerical and experimental investigations on the draft tube performance have confirmed the importance of the inlet swirling flow created by the runner vanes. The results indicate that it is still a challenge to get the optimal flow distribution at the draft tube inlet which gives the best machine performance over a range of operation points. Consequently, there is a need to adjust the runner-draft tube coupling to minimize the losses arising from the inlet flow distribution. This paper focus on establishing an optimization methodology for maximizing the draft tube performance as a function of the inlet velocity profile. The overall work is divides into two parts: The part one establish the inlet velocity parametrization, the numerical optimization set-up and the objective function definition. The part two validate the numerical CFD draft tube model. These steps are represented by the coupling of the commercial softwares MATLAB, FLUENT and iSIGHT. It is considered that this proved methodology will help to find a inlet velocity profile shape which will be able to suppress or mitigate the undesirable draft tube flow characteristics. [ABSTRACT FROM AUTHOR]

Two models are considered for propagation of acoustic waves in the water conduits of Francis turbines at hydroelectric power plants (HPP). Transfer functions are cited for a dynamic 'pressure-conduit/turbine/draft-tube' system during a pressure disturbance beyond the turbine. Fulfillment of the Nyquist criterion for the above-mentioned system indicates its stability at any openings of the final-control element. Analysis of analytical relationships between frequency characteristics and parameters characterizing the wave properties of sections of the water conduit makes it possible to isolate frequency regions in which manifestation of resonance is possible, and also evaluate its amplitude. The frequency response of the water conduit at the Sayano-Shushenskaya HPP, for which three resonances are isolated in the ultra-low acoustic region is given in the conclusion. A mathematical model of the process is developed and investigated. Oscillograms of pressure pulsation during pressure disturbances in the final third of the draft tube are presented. Results of the investigation are compared with published data derived from full-scale tests. [ABSTRACT FROM AUTHOR]

The flow rate measurements are the most difficult part of efficiency tests on prototype hydraulic turbines. Among the numerous flow rate measurement methods, the Winter Kennedy method is preferred for measuring turbine flow rates, since it is convenient, practical and economical. This paper describes efficiency tests on a large 300 MW Francis turbine, with the flow rate measured using the Winter Kennedy method and the Winter Kennedy flow rate coefficient calibrated using the Gibson method. The measured turbine efficiency curve is then compared with the curve provided by the manufacturer. The CFD calculations including the spiral case are then used to analyze the influence with the coefficient K and index n in the Winter Kennedy flow rate formula on the flow rate measurement. The uncertainty values of n and K are a key reason for the differences between the curves obtained from the efficiency test and the curves provided by the manufacturer. [ABSTRACT FROM AUTHOR]

number of suggestions directed toward assurance of high reliability for components of hydraulic-turbine equipment operating under vibration-induced loads and a corrosive medium are examined. [ABSTRACT FROM AUTHOR]

In this paper, a novel Bayesian-Gaussian neural network (BGNN) is proposed and applied to on-line modeling of a hydraulic turbine system (HTS). The new BGNN takes account of the complex nonlinear characteristics of HTS. Two redefined training procedures of the BGNN include the off-line training of the threshold matrix parameters, optimized by swarm optimization algorithms, and the on-line BGNN predictive application driven by the sliding window data method. The characteristics models of an HTS are identified using the new BGNN method and simulation results are presented which show the effectiveness of the BGNN in addressing modeling problems of HTS. [ABSTRACT FROM AUTHOR]

In order to investigate the feasibility of monitoring the fatigue cracks in turbine blades using acoustic emission (AE) technique, the AE characteristics of fatigue crack growth were studied in the laboratory. And the characteristics were compared with those of background noise received from a real hydraulic turbine unit. It is found that the AE parameters such as the energy and duration can qualitatively describe the fatigue state of the blades. The correlations of crack propagation rates and acoustic emission count rates vs stress intensity factor (SIF) range are also obtained. At the same time, for the specimens of 20SiMn under the given testing conditions, it is noted that the rise time and duration of events emitted from the fatigue process are lower than those from the background noise; amplitude range is 49–74 dB, which is lower than that of the noise (90–99 dB); frequency range of main energy of crack signals is higher than 60 kHz while that in the noise is lower than 55 kHz. Thus, it is possible to extract the useful crack signals from the noise through appropriate signal processing methods and to represent the crack status of blade materials by AE parameters. As a result, it is feasible to monitor the safety of runners using AE technique. [ABSTRACT FROM AUTHOR]

The features of unsteady flow such as pressure variation and fluctuation in a large hydraulic turbine usually lead to the instability of operation. This article reports the recent in site investigation concerning the characteristic frequencies in pressure fluctuation, shaft torsional oscillation and structural vibration of a prototype 700 MW Francis turbine unit. The investigation was carried out for a wide load range of 200 MW-700 MW in the condition of water head 57 m-90 m. An extensive analysis of both time-history and frequency data of these unsteady hydraulic behaviours was conducted. It was observed that the pressure fluctuation in a draft tube is stronger than that in upstream flow passage. The low frequency with about one third of rotation frequency is dominative for the pressure fluctuation in part load range. Also the unsteady features of vibration of head cover and torsional oscillation of shaft exhibited the similar features. Numerical analysis showed that the vibration and oscillation are caused by vortex rope in the draft tube. In addition, a strong vibration with special characteristic frequency was observed for the head cover in middle load range. The pressure fluctuation in the draft tube with the same frequency was also recorded. Because this special vibration has appeared in the designed normal running condition, it should be avoided by carefully allocating power load in the future operation. [ABSTRACT FROM AUTHOR]

During the entire service of the Bratsk HPP, work has been carried out to resolve problems related to technical refitting and reconstruction of electromechanical and hydromechanical equipment. [ABSTRACT FROM AUTHOR]