Pelton Turbine Bucket Research Articles

Advanced high‐precision methodology for assessing sediment erosion in Pelton turbine buckets

Advanced high‐precision methodology for assessing sediment erosion in Pelton turbine buckets

Numerical analysis of cavitation characteristics on front surfaces of different Pelton turbine buckets

Abstract Cavitation may occur in the runner bucket of the Pelton turbine, which could lead to cavitation erosion on the bucket surface. In this paper, three types of bucket were selected to carry out transient multiphase flow simulation at the same operating point of a model Pelton turbine. The hydraulic performance and cavitation characteristics of different buckets were analysed. The 3 bucket models were developed for Pelton turbines operating under the middle-high and the high-water head range, respectively. Results showed that the participation of cavitation model in simulation would slightly affect the working process of the bucket. The cavitation on the front surface of three buckets all happened at the beginning stage of jet inflowing the bucket, among which bucket C had the most serious cavitation on the front surface. This work showed different cavitation characteristics among various types of bucket, and the relevant result suggested comprehensive design considering cavitation characteristics should be done on the front surface of the bucket for a specific range of water head.

Experimental Study of Sediment Erosion in Pelton Turbine Bucket

Abstract In hydroelectric power plants (HPPs), sediment-laden water flows through entire turbines, causing components to be damaged over time. Pelton turbine components serve abrasive erosion from particle hardness, and rough surface when subjected to high flow velocities and various jet impingement angles. In this study, an experiment was conducted to examine the erosion-prone areas of a small-scale Pelton turbine bucket under actual flow conditions. For the experiment, the Pelton bucket was painted with four distinct layers of paint: red, yellow, green, and blue. These layers served as indicators, helping us to visually track the erosion process. The setup was specifically designed to inject sediment upstream of the nozzle. It operated for a significant period of 0- 30 minutes, and every 5 minutes, the erosion pattern was noted with the nozzle fully open at 10 l/s and a net head of 6m with jet impingement angle 75°, 90°, and 105°. After operating for 0-30 minutes in sediment-laden flow conditions, a pattern of erosion was revealed, showing the hot spots (areas more susceptible to erosion) during the investigation at jet angles of 75°, 90°, and 105°. The most severe erosion areas are in the bucket domain, specifically at the splitter region and the deeper upper and lower parts of the brim. The erosion mechanism was influenced by the jet diameter and impingement angle on the bucket splitter. The experiment revealed that the outer regions of the bucket, where the flow was directed outward, suffered the most severe erosion, providing evidence of particle separation at high accelerations.

Investigation on sediment erosion in bucket region of Pelton turbine considering cavitation

In the context of constructing high-head hydro-power stations, the Pelton turbine assumes a critical role as the primary energy converter. This study employs the Eulerian–Lagrangian method to simulate the multi-phase flow occurring within the Pelton turbine bucket. Furthermore, it introduces a novel aspect by investigating and comparing the effects of cavitation on erosion within the bucket region under varying conditions of sediment-water, involving different particle sizes and concentrations. The research findings unveiled several key insights. Primarily, cavitation predominantly influences the flow characteristics of particles at the air–liquid interface, while particles with larger sizes tend to concentrate in the center of the jet. Consequently, cavitation's impact on erosion is more pronounced in the case of smaller-sized particles. Moreover, the study revealed that cavitation can either exacerbate erosion under high particle concentration conditions or mitigate it when particle concentration is low. Furthermore, the investigation highlighted variations in the degree of erosion and the affected area of the bucket based on different position angles. Particularly, at a position angle of 65°, the presence of water vapor induced by cavitation alters particle trajectories, thereby modifying the overall erosion pattern of the bucket. These findings collectively contribute to a deeper understanding of the complex interplay between cavitation and erosion within the Pelton turbine bucket.

Development of a Novel High Head Impulse Hydro Turbine

The Pelton turbine has been widely regarded as the most efficient hydro turbine for high-head applications. However, the Pelton turbine buckets, especially the area commonly referred to as the ‘splitter’, are highly susceptible to erosion, drastically reducing efficiency over prolonged periods of time. This paper demonstrates a novel turbine idea that has been validated through both computational and experimental methods. This turbine addresses the issues associated with the erosion of the splitter through a redesign of the Pelton turbine to remove the need for a splitter and therefore potentially reducing downtime due to maintenance. The computational fluid dynamics (CFD) simulation results show that the turbine is capable of efficiencies greater than 82% with room for further improvement. The practical experimental results also show efficiencies within 6% of an optimized Pelton turbine. The results from this study indicate that through further optimization this turbine design could provide a means to produce power outputs similar to conventional Pelton turbines, with the added benefit of lower maintenance costs.

Experimental and numerical investigation of hydro-abrasive erosion in the Pelton turbine buckets for multiphase flow

Sediment erosion-corrosion is a critical threat to the safe operation of hydro turbines, which may lead to component damage or even complete failure of the turbine. A lack of understanding of the mechanism of sand erosion is a barrier to developing an erosion model to exactly quantify sand erosion in the Pelton turbine. The preeminent objectives of this research work are to determine parameters that influence sand erosion, identify erosion-prone areas in Pelton turbine buckets, quantify the erosive wear experimentally and numerically, determine the impact of erosive wear, and analyze the microscopic mechanism of erosion. Five Pelton buckets made of aluminum, carbon steel, stainless steel, polylactic acid (PLA), and acrylonitrile butadiene styrene (ABS) were used to perform erosion experiments under two-phase, solid-liquid flow conditions. Multi-layer paint modelling technique was used to identify erosion-prone areas. Optical profilometry was used to perform surface roughness analysis and Scanning Electron Microscopy was used to evaluate the microscopic degree of damage due to erosive wear in the Pelton bucket. Mass loss and thickness reduction analyses were performed to quantify the erosive wear. The erosion rates of aluminum, carbon steel, stainless steel, and ABS were 190 %, 86.73 %, 48.79 %, and 5.61 % higher, respectively, compared to PLA and both PLA and ABS demonstrated exceptional resistance.

Review on erosion phenomenon, maintenance, and financial calculation of lifetime as an asset for Pelton turbines

Prevention of greenhouse emissions is the top priority for all countries, which urges them to switch to renewable energy as much as possible. Hydropower is one of the renewables that have high flexibility and at the same time compatibility to be used with any other renewable sources. Moreover, hydropower plants operating in the Himalayas, Andes, and Alps are facing operational challenges due to the high concentration of sediment loads in rivers. Although the arrangement of traditional sediment control mechanisms like dams and sand traps, the erosion tendency of hydro-turbine components operating in this sediment-laden water increases with the increased concentration of sediments. Much past research has been directed towards understanding sediment behaviors, investigation of flow, and effect of concentration, shape, and size, especially with Francis turbines. However, there are very fewer studies regarding sediment erosion and flow behavior in the case of the Pelton turbine. Hence, delving deeper into the flow characteristics, sediment behavior, and performance of the Pelton turbine is important to better understand the flow and sediment pattern of these types of turbines. The paper consists of the evaluation of studies conducted on the flow pattern in the Pelton turbine buckets and its validation with the numerical analysis models using image processing. It is being used in the Waterpower Laboratory at the Norwegian University of Science and Technology, NTNU. This paper also evaluates the scope of investigations about erosion by sediments in Pelton buckets using image analysis and state-of-the-art technology in the hydropower sector. In addition, a review is done about the predictability of erosion based on the measurements of the quantity of sediments that passes through the turbine. This research paper can build a background for quantifying sediment erosion in Pelton turbines with a certain degree of error, which can be utilized as a reference in future studies. The life cycle estimation of a turbine is also analyzed with the consideration of its location and financial return requirements together with the type of maintenance that it may have and the repair that is foreseen, in the case of a non-coated surface.

Water flow simulation in a pelton turbine bucket with variable bucket dimensions using computational fluid dynamic

Today, especially among industrialized and developing nations, the usage of renewable energy sources is growing in popularity as a means of supplying energy needs. One of the renewable energy sources that is now being heavily exploited in Indonesia is the potential of water that may be used as a source of electrical energy by establishing a hydroelectric power plant (PLTA). One of the turbines that is frequently used in hydropower plants as a part that may transform water's kinetic energy into mechanical energy is the Pelton turbine. There is not a lot of literature on the design of Pelton turbine buckets. In order to determine the most ideal bucket dimensions that can be used with Pelton turbines, this study presents the conceptual and experimental components of the design and analysis of Pelton turbines based on bucket variations. AutoCAD was used to model the bucket and Pelton turbine, and ANSYS Fluent was used to perform the simulation so that results could be analyzed later. By comparing the simulated data of the blade variants 1 and 2, the ideal blade dimension variation is identified by the blade simulation of variant 1. The blade variation 2 with average torque of 5.859 Nm, average angular velocity of 40.822 rad/s, and average power of 242,970 watts is the most ideal blade. With an average torque of 4,735 Nm, an average corner speed of 40,404 rad/s, and an average power of 196,794 W, the blade 3 model has lower values

DESIGN AND ANALYSIS OF HYDRO TURBINES USING CFD

The aim of the present work is to carry out the free surface flow in a Pelton turbine bucket. Steady state numerical simulation has been done for the single bucket, for this the fixed configuration of Pelton turbine bucket is considered. The dimensions of the bucket are to be varied for the same conditions of discharge, head, and inclination of bucket to the jet. The numerical analysis is performed with the FLUENT code. The results provided by the analysis are compared for two profiles of Pelton buckets. The flow patterns in the buckets are analyzed from the results. An analysis of the losses due to the edge and the cutout of the bucket is also done. These results give the details as per expectation of steady flow calculations through the optimization process of the design of Pelton turbines.

SPH method used for characteristic predictions at Pelton turbine buckets: comparing with the mesh-based method

PurposeThe research in this paper helps to understand the difference between the Eulerian method and the Lagrangian method in describing the performance of Pelton turbine buckets, so as to improve the design level and design efficiency of the runner.Design/methodology/approachThis paper used DualSPHysics to calculate the unsteady flow of the Pelton turbine runner bucket and compared it with the mesh-based method to explore the difference between mesh-based and particle-based methods in torque curves, jet flow patterns and pressure characteristics.FindingsIt is noted that the particle-based method is challenging to compare with the mesh-based method concerning accuracy. In addition to better describing the free water film, the particle method also captures many droplets near the water film, but it cannot well describe the negative pressure region on the bucket back and the resulting jet interference after cutting off the jet. Compared with the mesh-based method, the pressure measurement points obtained by the particle-based method generally have shorter periods and violent fluctuations, and the pressure value of some points is underestimated.Originality/valueThis paper helped to calculate the unsteady characteristics of the Pelton turbine by Fluent, CFX and DualSPHysics; exploration jet flow pattern differences between the mesh and meshfree methods; prediction of the flow interference between the bucket back and the jet and the pressure curve of SPH usually has a shorter period and violent fluctuations.

Geometrical Optimization of Pelton Turbine Buckets for Enhancing Overall Efficiency by Using a Parametric Model—A Case Study: Hydroelectric Power Plant “Illuchi N2” from Ecuador

In Ecuador, the implementation of hydroelectric power plants has had a remarkable growth in the energy sector due to its high efficiency, low environmental impact, and opportunities to generate employment. One of the sectors with the greatest benefits from this type of energy has been the rural sector, where several small-scale hydroelectric plants (0.5 MW–10 MW) have been installed, usually with Pelton turbines. Although these turbines are highly efficient, one of the challenges is to obtain the optimal geometry of the bucket to take advantage of the greatest amount of energy from the water, avoiding the separation of the fluid. In this context, this study focuses on the development of an analytical and iterative methodology that allows for the determining of the appropriate dimensions of the buckets to achieve maximum turbine efficiency. For that, a parametric model has been proposed considering the dimensions and main angles of the bucket, the net hydraulic head and the working flow, as well as the power losses. The results of the model have been validated by means of CFD and by contrasting the experimental data obtained from the “Illuchi N2” Hydroelectric Power Plant in Ecuador, and it is concluded that it is possible to improve the turbine efficiency by up to 4%.

Analysis of hydro-abrasive erosion in Pelton buckets using a Eulerian-Lagrangian approach

One major concern in developing high-head water resources, which usually uses Pelton turbines, especially in geologically young and fragile mountains, is hydro-abrasive erosion. However, the physical mechanism of hydro-abrasive erosion in Pelton turbine buckets is still not well understood as the cumulative erosion is changing with the transient flow in rotating buckets. In this work, a new approach to predict the cumulative erosion on a rotating surface is proposed and applied to Pelton turbine buckets. This method is based on the Eulerian-Lagaraigian approach previously developed by authors and a novel algorithm introduced to predict the impact behavior of particles hitting rotating surfaces. The numerically obtained erosion is validated with 3D-scanned erosion profiles of buckets measured in a prototype plant. Further, a detailed analysis of the flow and hydro-abrasive erosion characteristics with bucket rotation is conducted. The good agreement with field values demonstrates the promising ability of the proposed method for quantitative erosion prediction. Interestingly, the flow interferences between the jet and the water sheet are found to produce a shield layer to prevent particles from directly impacting surfaces and consequently reduce hydro-abrasive erosion. The current work may provide important engineering insights for geometry optimization to reduce hydro-abrasive erosion.

Experimental and Numerical studies on Opening and Velocity Influence on Sediment Erosion of Pelton Turbine Buckets

Sediment erosion of Pelton turbines seriously damage the economic benefits and safe operation of the power station under the high head. The gas-liquid-solid three-phase unsteady flow calculation was carried out using the Eulerian-Lagrangian method to study the influence of velocity and nozzle opening on buckets torque and erosion. Experimental research were carried out under the condition of clear water and sediment-laden flow, the experimental results are in good agreement with the numerical simulation results, which proves the reliability of the calculation model and calculation method. The conclusions obtained from the numerical simulation are as follows: after adding the sediment particles, there is a slight delay of the bucket torque curve. Compared to clear water, the maximum torque of a single bucket will increase by about 2% in sediment-laden flow under different scenarios (the particle concentration is 1%, the particle size is 0.1 mm, the velocity range is 28–32 m/s, and the nozzle opening range is 50%–100%). For particles with strong flowability, the erosion region is highly consistent with the high-pressure zone. The increase in the velocity will increase the erosion rate on buckets. The nozzle opening change has little effect on the erosion region and maximum erosion rate. Meanwhile, the number of eroded buckets is three at the same moment, which is not affected by the nozzle opening change. This paper could provide some theoretical assistance for runner manufacturing, optimization design, and maintenance.

A review on erosion of a Pelton turbine bucket

Hydro-power energy is the most efficient renewable energy sources in the world. India stands in the top ten hydropower generation countries list. Pelton turbine is a well-known hydropower extraction machine. The Pelton turbine buckets play an important role in the efficiency of the hydro turbine which is in continuous interaction with high velocity jet and there are possibilities of damages to the bucket in the form of erosion as water contains small debris as sediments. Eroded buckets greatly reduce the efficiency of the turbine. Attempt is made by researchers to developed co-relations to evaluate wear rate and efficiency reduction based on the practical data. The majority of erosion takes place at splitter areas. An erosion cannot be eliminated, but it can be reduced by some amount. The results of the mathematical model indicate that the effect of silt size to the wear rate is 0.0001 gram per gram of bucket weight for a particular silt concentration and the result of silt concentration to wear rate is 0.0007 gram per gram of bucket weight for a particular silt size. The normalised efficiency loss is increased to 0.13% for a specific silt size with the variation of silt contraction. The average wear rate is nearly 3.1 mm per year for laboratory-scale Pelton turbine bucket; which is manufactured from brass and bronze materials. The coating of various materials over the buckets are used by researchers to reduce erosion. Among all coating materials, WC-Co-Cr gives better results against erosion.

Selection of Erosive Wear Rate Parameters of Pelton Turbine Buckets using PSI and TOPSIS Techniques

Hydro turbine machineries erosion due to silt is a complex issue for the effective practice of hydropower plants. Erosion caused by silt of the Pelton turbine buckets is a compound phenomenon that depends on size of silt particles , silt particles concentration , velocity of jet , and working time . This paper deals with the influence of silt erosion for various silt loaded factors and effective parameters. The preference selection index (PSI) and technique for order of preference by similarity to ideal solution (TOPSIS) approaches has been adopted to find optimal set of parameters which offers the highest performance for the Pelton turbine. Based up on the results obtained from both PSI and TOPSIS approaches it is found that optimal performance has been provided by A-1 alternate with geometric and flow parameters as , , and respectively.

Novel trends in modelling techniques of Pelton Turbine bucket for increased renewable energy production

Pelton turbines have been used for harvesting clean energy from water jet for over 100 years. The wide range of their applicability and the robustness with minimal onsite monitoring and carbon free energy production makes them one of the most desired hydro turbines for renewable energy production. Pelton turbine buckets are subject to complex turbulent multiphase flows with free surfaces, thus received lot of attention from Computational Fluid Dynamics (CFD) researchers to visualise the flow patterns. In addition, the bucket geometry optimization has been a prevalent research stream using analytical and graphical methods. Both of these investigations fields have resulted in significant improvement in the performance of the Pelton Turbine system. However, the design investigations for each feature are carried out independently due to the complexity in incorporating large number of design parameters. Thus, analysing the complex fluid flow on each pre-optimized design was rather challenging due to expensive computational needs of CFD and limited manufacturing possibilities. Today, development of accurate and inexpensive CFD models and innovative manufacturing technology such as rapid prototyping has made complex freeform shape possible to simulate and manufacture. Hence, any bucket designs disregarded in optimization on the basis of manufacturing feasibility can now be possible to manufacture and is worth investigating. This will require the combination of CFD and design optimization field of investigation with novel analysis approach. This paper examines these fields of studies with the view to establish the background for such novel approach. This approach could be a foundation for design optimization of turbomachinery or any reaction surface leading to increased production of renewable and sustainable energy from existing resources.

Experimental study of converging-diverging nozzle to generate power by Trilateral Flash Cycle (TFC)

Recovering heat from low grade heat resources for producing power is of high demand and interest. For this purpose, the an experimental study of converging-Diverging nozzle to generate power in Trilateral Flash Cycle (TFC) is investigated in this paper. In the proposed system, performance of a designed and manufactured to recover the heat and convert the heat energy to mechanical energy has been investigated. In this system, Isopentane, which is selected to be the working fluid due to its low boiling temperature, is heated by low temperature hot water and pumped through a two-phase flow nozzle, where the energy conversion takes place. In the nozzle, part of the liquid evaporates and the accelerated mixture exits the nozzle and impacts on a Pelton turbine bucket shape target. The high potential of power generation from low temperature heat resources is demonstrated through theoretical analysis. Generated force of high speed flow out of two phase nozzle has been experimentally measured in lab scale test rig and isentropic efficiency of the nozzle has been calculated based exit speed of the working fluid. Around 45% isentropic efficiency has been shown From the test results. In addition, 1.5 N–4 N force increase was detected by increasing temperature of working fluid from 30 °C to 70 °C correspondingly. The results of this experiment can be applied on a power plant waste heat as a case study, where the increased energy conversion efficiency is demonstrated on the binary cycle.

Smart Design and Development of a Small Hydropower System and Exploitation of Locally Sourced Material for Pelton Turbine Bucket Production

Small hydropower (SHP) systems are known to be an environmentally friendly, cost-effective and simple form of renewable energy production, appropriate for rural and standalone electrification. Greater access to power in sub-Saharan Africa (SSA) can be facilitated through domestic design and development of SHP components and systems. Domestic participation in the design, manufacturing of SHP components and application of SHP systems can be promoted through SHP capacity building and the use of locally sourced materials. This study, therefore, involves the design of both civil and mechanical aspects of SHP, and the use of locally sourced materials and manufacturing processes, in the design and production of Pelton turbine buckets. The study succeeded in the coding of a SHP system design and the development of design charts using MATLAB. A390 and A390-5 Mg cast aluminium alloys were selected and investigated as Pelton bucket materials using Solidworks modelling and simulation software. The performance of the materials as measured by von Mises, displacement and strain results were outstanding: the probe maximum stress was 6.7 × 107 N/m2, located along the splitter; the FOS was 4.5; fatigue damage and load safety for fully reversed loading at 106 cycles were 0.001 and 2.03, respectively.

CASTING IMPROVEMENT BASED ON METAHEURISTIC OPTIMIZATION AND NUMERICAL SIMULATION

This paper presents the use of metaheuristic optimization techniques to support the improvement of casting process. Genetic algorithm (GA), Ant Colony Optimization (ACO), Simulated annealing (SA) and Particle Swarm Optimization (PSO) have been considered as optimization tools to define the geometry of the casting part’s feeder. The proposed methodology has been demonstrated in the design of the feeder for casting Pelton turbine bucket. The results of the optimization are dimensional characteristics of the feeder, and the best result from all the implemented optimization processes has been adopted. Numerical simulation has been used to verify the validity of the presented design methodology and the feeding system optimization in the casting system of the Pelton turbine bucket.

PEMANFAATAN PADUAN AL (SCRAP) SEBAGAI BUCKET TURBIN PELTON MENGGUNAKAN METODE PENGECORAN EVAPORATIVE

Aluminum rongsok (scrap) is widely produced from households, IKM, offices, factories and so on in South Kalimantan. Along this time Al rongsok only collected by the collectors and then sold to the company smelting (in Java). Al rongsok can be recycled and used as a cast product, so potentially produce components, one of which is Pelton turbine bucket. This research aims to; (1) to create a prototype Pelton water-type bucket turbine using styrofoam pattern (2) to know the micro structure, hardness, tensile strength, and impact strength. The furnace for smelting uses a krasibel type furnace with charcoal wood fuel. Material for casting used Al alloy (scrap). The evaporative casting method is to use styrofoam as a molding pattern that is dumped in the printed sand. This method will produce castings that match the pattern / model formed. Melting is done by melting the Al in the kitchen krusibel then poured on the variation of casting temperature 650, 670, 690 and 710 oC. The casting results are then tested for mechanical properties (micro structure, hardness, tensile strength, and impact strength). The test results concluded, Al alloy (scrap) can be utilized and developed as prototype of cross flow water turbine blade / bucket using evaporative casting method. the higher the temperture of the hypereutectic Si structure is present between the dendrite Al of thin short flakes into thick, long bits. At temperatures above 650 oC, the value of hardness decreases with the increase of pouring temperature, while tensile stress decreases with increasing of pouring temperature. Impetus has been declining as the pouring temperature increases. Keywords: Evaporative casting, Al (Scrap), physical-mechanical properties, Pelton turbine bucket