Hydraulic Turbine Research Articles

Numerical study of the influence of blade inlet design parameters on the internal flow characteristics and energy performance of a Francis turbine

One of the challenges of hydraulic turbine design is the creation of a conveyor with high hydraulic performance in accordance with the parameters of the hydraulic energy. The blade inlet parameters, such as blade beta angle, lean angle, and ellipse axis ratio, have an effect on the performance and cavitation characteristics of the runner, among the numerous geometric elements that regulate turbine performance. All of these parameters must be optimized to ensure that the runner inlet is matched to the guide vane under design conditions and a wider range of off-design conditions. For hydraulic designers, computational fluid dynamics based performance prediction methods can provide rapid turbine performance predictions and expedite runner development. Finding a collection of accessible parameters, meanwhile, strongly depends on the designer’s previous design work, which is frequently time-consuming. In this article, the internal flow characteristics and energy performance of a Francis turbine with moderate specific-speed, as well as the blade leading edge geometrical parameters that influence them, are investigated in depth. The Francis turbine is designed in accordance with the rated head H (m), rated flow rate Q (m), and rated speed n (rpm) within the constraints of the fixed meridional projection, including the leading-edge and trailing-edge positions. The energy performance, internal flow characteristics, velocity profile, flow angles, pressure distribution, blade loading, and cavitation characteristics are computed, analyzed, and compared. The main findings can serve as a guide for the development of Francis turbines with moderate specific-speed.

Vortex breakdown in discharge cone of the Francis Turbine

Hydraulic turbines are usually operating at high efficiencies around 90%. It is possible to increase the efficiency by preventing flow characteristics such as failure, cavitation and vortex rope in the draft tube. In some cases, such as partial loads or overloads, pressure pulsations and vortex rope would occur in the draft tube. These undesired events would damage the components of the turbine and that also causes the efficiency to decrease. To eliminate these artifacts, it is decided to design a new component. Vortex Preventing Element, which is designed to eliminate vortex structures and pressure fluctuations, is located at the inlet of draft tube. Computational Fluid Dynamics analyses are performed for different designs having several stage numbers of vortex preventing elements. The preliminary results showed that the one stage vortex preventing element design creates more uniform flow in the draft tube and also increases the efficiency about 3%. Since more studies about the vortex preventing element are in progress, it could be said that the vortex preventing element can handle vortex phenomena in the draft tube and effects the efficiency of the Francis turbines.

ДОСЛІДЖЕННЯ ЕФЕКТИВНОСТІ ТЕПЛООБМІННОГО ПРОЦЕСУ В ОХОЛОДЖУВАЧІ ТУРБІННОГО МАСТИЛА МО-2 В ЗАЛЕЖНОСТІ ВІД СХЕМИ РОЗТАШУВАННЯ ТРУБОК У ТРУБНИХ ҐРАТАХ

Effective cooling of the turbine oil is important for the reliability and optimal operation of the turbogenerator. The oil is used for lubrication and cooling of the support and radial bearings of the turbine, bearings of the generator and reducer, gears and splined rollers. It is also used as a hydraulic fluid in the hydraulic turbine start-up system. For reliable and safe operation of the system, it is necessary to maintain the correct temperature of the lubricant. Research is aimed at studying the influence of the layout of the heat exchange tubes in the tube grids on the cooling efficiency of the TP-22 turbine oil. With the help of the SolidWorks software complex, a geometric model of the MO-2 turbine oil cooler was created with three schemes for the placement of heat exchange tubes in tube grids: corridor, radial and checkerboard. Adhering to the parameters of the technical characteristics of this cooler, the nominal parameters of temperatures and consumption of coolants (cooling water and turbine lubricant TP-22) were chosen. The result of the calculations were the temperature fields of the coolants and the trajectories of the movement of lubricant particles in the intertube space of the cooler. When creating a geometric model and further research, the main technical characteristics of the shell-and-tube horizontal cooler MO2 were adopted, namely: the temperature of the turbine oil at the inlet is 45°С, the nominal flow rate of the oil is 3.1 m3/h, the temperature of the water at the inlet is 20°С, the nominal flow rate water - 15 m3/h. The conducted computer modeling made it possible to investigate the influence of the layout of the heat exchange tubes in the tube grids on the cooling efficiency of the turbine lubricant in the MO-2 shell-and-tube cooler. It was shown that the most effective, among the studied schemes, is the checkerboard arrangement of heat exchange tubes in tube grids. This scheme makes it possible to reduce the consumption of cooling water, relative to the nominal one, which will allow the use of water pumps of lower power.

Assessment of the residual life of turbine runners with operational defectiveness

The residual life of the runners of hydraulic turbines in the presence of operational defects is estimated. The main problems of the operation of hydraulic turbines associated with technological defects and exhaustion of the standard resource are described. The main requirements for initial data to be used in estimation of the residual resource and the requirements for predicting the residual resource of runners based on the results of surveys and analysis of their technical condition are specified. We have classified and briefly described the applied approaches and techniques used in estimation of the residual resource. The main damaging factors affecting the residual life of the runners are revealed: deformation aging of the metal, cavitation, corrosion and fatigue damage to the elements of runners. The most characteristic defects are divided into three groups: zones of cavitation erosion; corrosion-fatigue cracks; and weld defects. Particular attention is paid to corrosion-fatigue cracks identified using flaw detection. The mechanism of crack formation and the most probable location of the cracks in the runner are shown. Statistical data on the number of cracks at the onset of the runner operation and at the time of shutdown maintenance are presented. The main statistical parameters of the sample and the parameters of crack size distributions including the distribution law are determined. The distribution law is exponential for the crack length parameter; whereas for the crack opening width it is log-normal. The revealed multidirectional cracks are located at the surface, subsurface or inner layer of the metal. They arise from operational defects (ulcers, craters, undercuts or delamination) and grow during operation of the turbine units. We also present the design schemes of elements with cracks used for quantification of resources according to the criteria of fracture mechanics. The results of calculations for static and dynamic crack resistance are presented as the dependence of stress intensity factors on the crack size. The levels of the total accumulated damage to the runners, the values of the residual life at the stage of crack nucleation and development were determined for 11 hydraulic units in the «start-stop» and «working» cycles. The main conclusion is that the total operating time of the hydraulic turbine runners significantly exceeds the standard operating life, while the residual resource is insufficient for a further period of long-term operation.

Application of artificial intelligence and communication technology to water and energy balance models

Abstract The precise correction of water and energy balance is a significant difficulty in studying turbulence energy balance and water flow for agricultural purposes. The need for efficient water and energy management is growing as the world struggles to keep up with rising water and energy demands. This research examines artificial intelligence (AI)'s impact on the water flow and energy balance confluence subnetwork of sensing elements from all the original network's nodes. The study proposed an AI-based optimized sensor energy balance model (AI-SEBM) that uses pressure data to maintain energy balance in turbines and save water with the optimized energy source for agriculture usage. This research explores the potential for installing Kalpan hydraulic turbines, which are most effective during half-load operation, and to forecast all loads with little computing effort to balance energy in turbulence. To anticipate daily pressure readings and energy consumption across all nodes in the network, an AI-based optimization wireless sensor network is designed for communication and linked to an energy balance system. Sensors are strategically deployed at the network's nerve centres. The maximum flow algorithm is used for a grid representing the water and energy balance to determine the positions of the virtual nodes.

Nonlinear recursive gain asymptotic tracking controller design for hydraulic turbine regulating systems

AbstractThis paper focuses on the nonlinear asymptotic tracking control for a hydraulic turbine regulating system (HTRS). The proposed control approach combines a recursive gain control scheme with an adaptive technique to achieve asymptotic tracking. An important characteristic feature of the proposed controller is the incorporation of a smooth function with a time‐varying function that is integrable and positive. This function provides the developed controller with sufficient power to achieve asymptotic tracking, whereas the recursive gain control alone can ensure that tracking errors converge exponentially to zero within balls of any arbitrarily small radii. The simulation results demonstrate the efficacy of the presented control technique, which outperforms backstepping, command‐filtered backstepping, dynamic surface, synergetic control designs; deals with the “explosion of complexity” problem; and simultaneously achieves asymptotic tracking. Furthermore, even though the HTRS parameters vary, the proposed technique is capable of providing consistent control performance. As a result, the presented controller is unaffected by changes in the system's parameters.

Application of the 3D Inverse Design Method in Reversible Pump Turbines and Francis Turbines

The increasingly stringent requirements in terms of flexibility and efficiency for hydraulic turbines pose new challenges for designers. Although computational fluid dynamics has offered new opportunities to significantly improve the performance in the preliminary design phase, the design of a hydraulic turbine still represents a challenging task requiring considerable engineering input and know-how. In such a scenario, the inverse three-dimensional design strategy has recently demonstrated its effectiveness in improving the machine performance, and interesting applications have been proposed for Francis turbines and reversible pump turbines. This paper presents and discusses the most interesting design solutions so far documented. The influence of blade staking and load distribution on the hydrodynamic performance is discussed. Finally, optimized blade load distributions are reported to provide useful design guidelines for the development of the new generation of hydraulic turbines.

Stability comparison of different controllers for hydraulic turbine fractional order interval parameter time-delay system

This paper studies the stability comparison of four controllers for a hydraulic turbine fractional order interval parameter time-delay system. Considering the terms of parameter uncertainty and time-lag, the hydraulic turbine fractional order interval parameter time-delay system is established by using fractional calculus and identification technology. Through the edge theorem and D-decomposition method, the calculation process of controller parameter stability region is derived in every detail. Subsequently, the four different controllers including the PID, PID plus second order derivative (PID2D), fractional order PID (FOPID) and fractional order PID plus second order derivative (FOPID2D) controllers, are applied in the hydraulic turbine fractional order interval parameter time-delay system. According to the experimental results, the effect of the controller parameters kd , kd 2, α and λ on the stability region of the parameters kp and ki is analysed and the variable law of stability regions of the hydraulic turbine governing system is presented. Finally, the stability region of these four controllers is compared and the results validate the superiority of the FOPID2D controller over the other controllers.

A Review of the Efficiency Improvement of Hydraulic Turbines in Energy Recovery

Turbine energy recovery is a process energy saving technology, and understanding turbine efficiency has important operational and economic benefits for the operator of a power plant. There are three main areas of research into turbine energy efficiency: the structural performance of the turbine itself, the configuration of the recovery device and the regulation of operating conditions. This paper summarizes recent research advances in hydraulic turbine energy efficiency improvement, focusing on the design factors that can affect the overall efficiency of a hydraulic turbine. To quantify the impact of these factors, this paper investigates the effects of surface roughness, flow rate, head and impeller speed on overall efficiency. Methods for optimizing improvements based on these design factors are reviewed, and two methods, the Box–Behnken Design method and the NSGA-II genetic algorithm, are described with practical examples to provide ideas for future research.

Dynamic Analysis and Metallographic Examination of Linings with Different Composite Contents used in the Brakes of a Hydraulic Turbine

Dynamic Analysis and Metallographic Examination of Linings with Different Composite Contents used in the Brakes of a Hydraulic Turbine

Modeling of the effect of ATH fillers on the rheology, curing kinetics, and flexural properties of the epoxy resin forming the hydraulic turbines’ stay vanes extension

Epoxy resins are crucial for the production of GFRP/XPS foam sandwich structures used for hydraulic turbine extension stay vanes. The quantity and size of ATH fillers have a significant impact on the curing and post-curing characteristics of the epoxy resin. This paper presents the results of an experimental study of the effect of ATH fillers on the maximum temperature, polymerization time, shrinkage, viscosity, and flexural properties of the epoxy resin. The study also uses regression and neural network methods to develop models to predict these properties based on ATH mass fraction and particle size. The results showed that increasing the mass fraction of ATH with a smaller particle size delayed polymerization and reduced the maximum temperature. The addition of ATH resulted in an improvement of the flexural modulus; nevertheless, it caused a reduction in both the flexural strength and breakage strain. Adding ATH improved flexural strength, modulus, and breakage strain. The models developed in this study had a high correlation between predicted and measured responses, providing valuable information for the design and casting of the proposed sandwich structures.

Hydrodynamic Model of Hydraulic Engineering Based on Trigonometric Function Relation Equation

Abstract In order to explore the application of fluid mechanics technology in water conservancy and hydropower stations, the author proposes the study of hydraulic engineering fluid mechanics model based on trigonometric function relationship equation. According to standard k- ε Double equation and Reynolds time average (N-S) equation, given the runner boundary conditions, establish the mathematical model of the internal flow of the hydraulic turbine. Through CFD simulation technology, the runner of hydraulic turbine is numerically simulated to obtain the velocity distribution and blade pressure distribution inside the runner, movable guide vane and fixed guide vane, the reliability of the design is improved, and the application of CFD technology in hydropower project is analyzed with an example. The results show that, when the diameter of guide vane distribution circle is 4760mm, the scheme is optimal, and the relative efficiency under the optimal working condition is 96.35%. The flow of the modified runner from the inlet of the volute to the outlet of the draft tube is very stable under the optimal working condition, and there is no obvious vortex, especially there is no obvious vortex belt and vortex at the outlet of the runner; There is no obvious vortex in the draft tube, the flow on both sides of the pier is very uniform, and the flow on one side is not significantly greater than that on the other side, which fully shows that the flow performance of the modified runner is good. After reconstruction, the runner outlet flow field is good, and the internal flow line of the draft tube is smooth. The application prospect of hydrodynamic algorithm for hydraulic engineering is relatively broad.

Numerical simulation of swirling flow modes in a model of a hydraulic turbine and a draft tube

Numerical simulation of swirling flow modes in a model of a hydraulic turbine and a draft tube

DEVELOPMENT OF HORIZONTAL BULB HYDROTURBINES FOR HIGH HEADS WITH A WIDE RANGE OF RELIABLE OPERATION MODES

The issues and directions for improving the energy-cavitation and operational performance of hydro turbine equipment of hydroelectric power plants are considered. The paper analyzes in detail the directions for improving the main indicators characterizing the energy and operational advantages of horizontal hydro turbines. Straight-axis Kaplan hydraulic turbines with a horizontal axis of rotation of the hydraulic unit have incomparable advantages compared to hydraulic turbines with water supply using a spiral case, in terms of higher throughput and a wider range of operation. The practice of hydraulic turbine construction has determined the range of heads for which different types of hydraulic turbines are used. The use of horizontal directflow hydraulic turbines for heads of more than 40 meters encounters a number of problems of a hydrodynamic nature, strength, and reliable operation. The paper analyzes the advantages of direct-flow bulb hydro turbines and the possibility of using them for high heads. New design solutions are considered, for which Ukrainian patents have been obtained, allowing the use of horizontal bulb hydraulic units for higher heads (up to 300 meters) and at the same time obtaining a wider operating area not only in terms of flow rates, but also in terms of heads. The use of twin bulb hydraulic units will significantly expand the operational ranges of highly efficient and reliable operation of horizontal bulb hydraulic turbines at flow rates (power) that allow them to successfully operate at variable peak loads of daily regulation. Based on the analysis of the working process of various horizontal and diagonal turbines, the analysis of their universal characteristics, scientifically based proposals was developed for the nomenclature of twin bulb hydraulic units. The design of a horizontal hydraulic turbine using inlet nozzle channels is presented. The use of nozzle diaphragms as elements that create the angular momentum necessary for optimal operation of the hydraulic turbine makes it possible to use bulb direct-flow hydro units for high heads (80–100 meters).

MATHEMATICAL MODEL OF THE ELECTRO-HYDRAULIC CONVERTER OF THE HYDRAULIC TURBINE SPEED CONTROL SYSTEM

Presents a mathematical model of an electro-hydraulic converter with proportional control. In the world and domestic practice of creating hydraulic turbine equipment, there is a clear tendency to create computer-based rotor speed control systems for hydraulic turbines. Computer systems provide an opportunity to implement the introduction of effective algorithms using software that improve the static and dynamic characteristics of the system. This in turn increases the importance of mathematical modeling both at the design stage and during commissioning. The analysis of the performed works devoted to the mathematical description of the elements of the hydraulic drive of the regulator showed that they are reduced to linearized equations without taking into account a number of important factors that will increase the accuracy of the mathematical model. Improvement of static and dynamic characteristics and the system as a whole can be achieved by solving the scientific problem of studying its dynamics based on the development of a more complete mathematical model. To reduce friction and hysteresis, to prevent obliteration, the electrohydraulic converter plunger in the lower part is equipped with a segner wheel. Improving the dynamic characteristics of hydraulic turbine speed controllers requires the development of nonlinear mathematical models with subsequent analysis of transients in the hydraulic drive of the speed controller. Evaluation of the quality of transient processes and subsequent adjustment of parameters allows to achieve a reduction in the duration of transients, increase the speed and accuracy of positioning at small movements of the servo motor. A number of unaccounted factors during the preparation of the mathematical model of the electro-hydraulic converter makes it possible to increase its adequacy to the real object of study and increase the speed of the control system of the rotor speed of the hydraulic turbine.

AN INNOVATIVE APPROACH TO THE DEVELOPMENT OF NEW SCHEMES OF HORIZONTAL DIRECT-FLOW HYDRAULIC TURBINES

The impact of the rapid development of renewable energy sources and the reduction of electricity production by traditional generating capacities on the change in the development trend in world energy is analyzed. This led to a sharp change in the priorities of the national energy policy of Ukraine with an increase in the capacities of renewable energy sources, which in 2035 should be 25 billion kWh of generating capacity against 2,8 billion kWh in 2018. It is shown that such trends require the growth of balancing highly maneuverable capacities in hydropower to regulate load schedules and ensure stability and reliable operation of combined power systems. Under such trends, Ukraine is transitioning to a new innovative model of the operation of the electric power industry in the conditions of the gradual creation of a full-fledged energy market and the planned integration of the energy system of Ukraine with the European energy system (ENNSO-E). It is claimed that the problem of covering peak loads becomes acute in the modern conditions of power system operation. This makes it necessary to pay more attention to the operation of maneuverable hydropower equipment in order to optimize the distribution of loads to consumers. It is proposed to solve these problems comprehensively, both by developing new blade systems and water passages of traditional type hydroturbines, and by improving the working process due to innovative constructive solutions for the layout of hydropower equipment for new hydropower facilities. Potetenko O. V. (Professor of the Department of Hydraulic Machines named after G. F. Proskura, NTU "KhPI") founded a scientific direction in which for 10 years the tasks of introducing high-speed bladed hydraulic turbines at high heads in the development of new design schemes in hydropower were developed and researched. Dozens of patents for inventions and utility models are the results of this. Further development of innovative schemes of horizontal capsule hydraulic units, which is related to the features of the working process, is aimed to achieve high average operating efficiency while simultaneously expanding operation and reliability areas of the proposed design schemes.

Experimental investigation on the characteristics and alleviation of the upper part load pressure fluctuation in a Francis turbine

The Francis turbine is a renowned reaction hydraulic turbine known for its remarkable ability to convert the energy of flowing water into mechanical energy. Operating near the best efficiency point, the Francis turbine experiences the upper part load pressure fluctuation, which is characterized by an abrupt high amplitude increment and decay and can put the stability of a power plant at risk. This study experimentally investigated the amplitude-frequency characteristics of this special pressure fluctuation. The findings indicate that the most powerful amplitude reaches up to 15.35% of the tested water head in the vaneless space, and the characteristic frequency ranges from 1.6 to 2.3 times the rotating frequency. Notably, the study has found that the vortex rope in the draft tube exhibits a slender and spring-like within the upper part load region, and it looks like a spring stretching and compressing during the evolution of vortex rope, implying energy accumulation and release. Furthermore, a technical approach to alleviate high-amplitude pressure fluctuation in upper part load region is proposed that controls the velocity distributions at the runner outlet. A comparison of experimental test evidence shows that an impressive result is obtained with a reduction of the maximum amplitude from 10.75% to 3.52% in spiral casing, and from 15.35% to 3.03% in the vaneless space. In addition, the first-order frequencies at the spiral casing are primarily reduced, while the draft tube shows local increment, and the runner blade passage frequency becomes dominant in the vaneless space.

Investigations of Spoilers to Mitigate Columnar Vortices in Propeller Turbines at Speed-No-Load Based On Steady and Unsteady Flow Simulations

Abstract With the introduction of an ever-larger share of renewable but intermittent energy sources on electrical grids, hydraulic turbines are more often used as network stabilizers. In such a role, they are generally operated in off-design operations like speed-no-load (SNL). No energy is extracted from the flow at SNL operation, but the runner rotates at the synchronous speed linked to the electrical grid. The flow inside the runner of low-head turbines operating at SNL is often dominated by a columnar vortex array that may induce damaging pressure fluctuations. This paper presents the study of a control device to mitigate those vortices. At SNL, the small guide vane opening leads to a high swirl in the runner generating secondary flows such as columnar vortices and backflows. The proposed concept is to move SNL operation toward a higher guide vane opening and hence lower swirl, preventing the formation of a columnar vortex array. Lowering the input swirl of SNL is accomplished by opening up the guide vanes while using a control device to limit the discharge. The control device, like a spoiler on an aircraft wing, is introduced on the guide vanes to generate added head losses, significantly decreasing the discharge. This paper compares the hydrodynamics of the flow in a propeller turbine with different spoiler geometries. The study is based on both RANS and URANS flow simulations. It highlights how such devices can successfully mitigate columnar vortices and their associated pressure fluctuations on runner blades.

Generation of Electricity From a Hydraulic Turbine in the Djonou River (Benin)

The shortage of electricity in rural areas despite the hydraulic potential they possess is becoming a challenge for Benin. To date, nearly 140,000 people spread over the 42 lakeside villages of this country live in energy inaccessibility, insecurity and poverty. To overcome this situation, the present study is therefore interested in the production of electrical energy on an experimental basis in low water periods thanks to an Archimedean screw turbine which operates at low flow rates and height of fall on the river. Djonou located in southern Benin a few kilometers from the University of Abomey-Calavi. The geometrical and hydraulic parameters of the screw were therefore determined and the device was modeled using Autocard software. A prototype was then made with local recycled materials and tested on the river. The screw specifications indicate an inside and outside radius of 0.072 m and 0.135 m. The length of the screw was set at 0.46 m for a blade radius estimated at 0.137 m. The number of screw blades is equal to 2 with a flow rate of 0.049 $ m^{3}/s $. The inclination angle of the screw is $25^{\circ}$. The device on the experimental site produces a voltage of 16 V and provides a current of about 0.12 A which can power a 2 W lamp. This performance of the prototype made on a small scale is a reliable indicator of the optimal use of this technology in the national hydraulic network of Benin to supply populations with electrical energy.

A Hybrid Algorithm Based on Social Engineering and Artificial Neural Network for Fault Warning Detection in Hydraulic Turbines

Hydraulic turbines constitute an essential component within the hydroelectric power generation industry, contributing to renewable energy production with minimal environmental pollution. Maintaining stable turbine operation presents a considerable challenge, which necessitates effective fault diagnosis and warning systems. Timely and efficient fault w arnings are particularly vital, as they enable personnel to address emerging issues promptly. Although backpropagation (BP) networks are frequently employed in fault warning systems, they exhibit several limitations, such as susceptibility to local optima. To mitigate this issue, this paper introduces an improved social engineering optimizer (ISEO) method aimed at optimizing BP networks for developing a hydraulic turbine warning system. Experimental results reveal that the ISEO-BP-based approach offers a highly effective fault warning system, as evidenced by superior performance metrics when compared to alternative methods.