Kaplan Turbine Runner Research Articles

Study on Structure Dynamic Characteristics for Internal Components of Kaplan Turbine Runner under Different Contact Modes

Study on Structure Dynamic Characteristics for Internal Components of Kaplan Turbine Runner under Different Contact Modes

Multibody dynamics analysis of a Kaplan turbine runner in full operating conditions

Low head hydraulic resources are important renewable energy, while the Kaplan turbine is an important equipment for developing it, and it provides important references for the development of tidal energy unit. The flow characteristics and the dynamic behavior of a prototype Kaplan turbine in full operating conditions have been analyzed on the basis of the fluid-structure interaction theory and the nonlinear multibody dynamics analysis method, and a kind of contour line which intuitively describes the behavior of the unit is proposed in this paper. The results show that the hydraulic torque and the torque caused by centrifugal force have opposite effect on the blade, wherein the hydraulic torque makes the blade tends to open and the torque caused by centrifugal force makes the blade tends to close. The dynamic response behavior of the multibody mechanism shows inconsistency between different components, while the dynamic stress and the combined torque show high consistency. The low head and large power operating condition is unfavorable to blade lever, with a mean stress of 130 MPa and an amplitude of 11 MPa. This paper is helpful for the in-depth understanding on the multibody dynamic behavior of the Kaplan turbine runner under the nonlinear effect and fluid-structure effect. The proposed contour lines of hydraulic excitation and dynamic stress in full operating conditions can provide guidance for the design and operation of the unit.

Determination of all hydrodynamic added properties resulting from fluid structure interactions using singular value decomposition

The hydrodynamic added effects such as inertia, damping and stiffness resulting from a fluid flow surrounding a structure strongly affect its dynamic response. Thus, accurate determination of such effects is of prime importance in the design of modern mechanical systems exposing fluid–structure interactions. The main goal of this study is to develop a unified methodology for the simultaneous identification of all hydrodynamic added effects caused by fluid–structure interactions. The proposed model is based on the least squares solution of an over-determined system of equations using singular value decomposition. The singular value decomposition determine the added inertia and stiffness without any assumption on their respective magnitude and variation, necessary for other methods. The method is firstly validated using the analytical solutions for single degree of freedom free vibration and forced oscillations under single and multiple frequency excitations for a variety of cases. It is found that the proposed method can predict all presumed added properties for transient forced oscillations under single and multiple external forces. Next, the method is applied to two challenging fluid structure interaction test studies; an oscillating hydrofoil in a turbulent flow and a Kaplan turbine runner subjected to single and multiple frequency perturbations. In both cases, the results of the proposed method are found to be consistent with results of methods in the literature and confirmed the underlying hypothesis of their analysis. The results confirm the ability of the newly developed methodology in evaluation all fluid added effects in complex engineering turbulent flows subject to one to several excitations, simultaneously.

Classic design of a kaplan turbine runner wheel

The Brazilian electric matrix is based on renewable sources of energy, and most of it comes from hydroelectric power plants, its structure is composed of a dam, a capture system, a spillway, and a powerhouse, in this installation are the water turbines The main types are Francis, Bulbo, Helix, Kaplan, and Pelton each one has particularity for dimensioning. In this context, the objective of the article is to carry out the classic design of a Kaplan turbine runner wheel and the computational design. For this, first, the runner wheel case study was defined considering those installed in Brazil, using as criteria the power energy efficiency. Later, based on the input data: flow, fall height, and runner rotation, the calculation memorial was developed, preliminary calculations to define the specific rotation, complementary calculations to determine the minimum runner flow, number of poles, specific design rotation, an outer diameter of the runner blade, hub diameter, the height of the distributor, solid shaft diameter, fluid flow velocity, profile lengths, and profile thickness. The Hydroelectric Power Plant case study was Luis Eduardo Magalhães, installed on the Tocantins River in the state of Tocantins, has five generator units with Kaplan runners of five blades and power of 180.5 MW each, the flow rate of 700 m³/s, drop height of 29 m and 100 revolutions per minute. The values obtained were organized in electronic spreadsheets and later the computational design of the runner was performed using CAD software. The dimensioned runner wheel has dimensional and power values similar to the case study. Thus, it is concluded that the application of the classic dimensioning allowed the design of the runner wheel containing five blades and power of 183.4 MW, and the computational design allowed us to visualize the similarities with the case study.

Low-head high specific speed Kaplan turbine for small hydropower – design, CFD loss analysis and basic, cavitation and runaway investigations: A case study

In an era of growing energy demand, it is necessary to reach for lower water potentials to be used by a hydro unit. Due to low damming, a hydro unit must be designed to allow the flow of as much water as possible with maximum efficiency. This ensures optimal use of hydropower and minimization of turbine size. Therefore, this paper presents the construction of a model Kaplan turbine (runner diameter of 300 mm) with a high specific speed, designed to work under ultra-low and low heads up to 3 m.Adjustable guide vanes and runner blades were designed by means of an inverse problem method using a two-dimensional axisymmetric model. In the case of the adjustable guide vane, two shapes have been designed. The first has a classical shape and the second has a non-classical shape. The influence of both guide vanes on the turbine operation was analysed using the CFD technique. As a result, the turbine with a non-classical shape blade has a higher hydraulic efficiency and the efficiency curve is flatter. As part of these calculations, many variants of turbine settings were analysed (192 cases), namely 4 angles of classical guide vanes, 4 angles of non-classical guide vanes, and 4 angles of runner as well as 2 angles of a conical draft tube and 3 rotational speeds. The energy losses occurring in the flow elements of the turbine and their mutual contribution are presented in this paper.Model experimental tests of the turbine were carried out on the test stand with a wide range of settings of the guide vanes (the tests used a guide vane with a non-classical shape), the runner and its rotational speed. The research is aimed at determining the basic parameters of efficiency, the effect of cavitation and the runaway speed. Cavitation and runaway characteristics as well as the results of the resistance torque (friction losses) and its share in the total moment are presented.As a result of design, analytical, and experimental works the low-head high specific speed model Kaplan turbine was obtained and diagnosed. The realization of large flows, combined with the high efficiency of the machine is always a difficult task. The paper briefly describes the shapes of the designed guide vanes and runner blade obtained by the inverse problem method. However, more emphasis has been focused on the presentation of model tests that are rare for this type of machine. Therefore, the measurement uncertainty, measuring devices and the course of the conducted basic performance, cavitation and runaway tests are described in detail. Additionally, for the selected cases, a visualization of the flow with forced cavitation in the runner during cavitation tests is also presented.

Numerical Model on the Dynamic Behavior of a Prototype Kaplan Turbine Runner

Experimental and numerical investigations of the modal behavior of a prototype Kaplan turbine runner in air have been conducted in this paper. The widely used roving accelerometer method was used in the experimental modal analysis. A systematic approach from a single blade model to the whole runner has been used in the simulation to get a thorough understanding. The experimental results show that all the detected modes concentrate their displacements on the impacted blade. The numerical results show that the modes of the single blade form different mode families of the runner, and each mode family corresponds to a narrow frequency band. Harmonic response analysis shows that, at the response peak point, the single blade excitation can only get mode shapes with concentrations on the exciting blade due to the superposition of the close modes in each mode family, which explains the experimental results well, while the mode superposition can be avoided by the order excitation method. With the reduction of the connection stiffness between the blades and hub/control system, the frequencies of most modes change from insensitive to more and more sensitive to the connection stiffness change, which results in a sensitive area and an insensitive area. Through comparison with the experimental results, it is indicated that the natural frequencies of the runner can probably be predicted by merging the runner into a whole body.

Numerical Investigation of the Trailing Edge Shape on the Added Damping of a Kaplan Turbine Runner

Hydraulic turbine runners experience high excitation forces in their daily operations, and these excitations may cause resonances to runners, which may induce high vibrations and shorten the runner's lifetimes. Increasing the added damping of runners in water can be helpful to reduce the vibration level during resonances. Some studies have shown that the modification of the trailing edge shape can be helpful to increase added damping of hydrofoils in water. However, the influence of blade trailing edge shape on the added damping of hydraulic turbine runners has been studied in a limited way before. Due to the difficulties to study this problem experimentally, the influence of blade trailing edge shape on a Kaplan turbine runner has been studied numerically in this paper and the one-way FSI method was implemented. The performances of three different turbulence models, including the k − ϵ , k − ω SST , and transition SST models, in the added damping simulation of the NACA 0009 hydrofoil were evaluated by comparing with the available results of the two-way FSI simulation in the references. Results show that, unlike the significantly different performances in the two-way FSI method, the performances of all the turbulence models are very close in the one-way FSI method. Then, the k − ϵ turbulence model was applied to the added damping simulation of a Kaplan turbine runner, and results show that the modification of the blade trailing edge shape can be helpful to increase the added damping to some extent.

Influence of internal blade-interactions on the added mass and added damping of a prototype Kaplan turbine runner

Different from other types of hydraulic turbines, the fluid–structure coupling vibration behavior of Kaplan turbine runners has still been studied limited before. One problem is that their blades can rotate according to load changes, and the internal interactions among the blades via the flow field may produce an important influence on the added mass and added damping of the runner, particularly when the blade angle is small. In this paper, the influence of internal blade-interactions on the added mass and added damping of a prototype Kaplan turbine runner has been studied numerically. An isolated stage model from the end of the stay vanes to the bottom of the hub with six blades was considered for simulation. The Acoustic Fluid-Structure Interaction (FSI) technology based on the Finite Element Method was used to investigate the added mass effect first and to provide the modal shapes and initial frequencies for the following one-way FSI analysis based on the Finite Volume Method. The natural frequencies predicted by the Acoustic FSI were compared with those from the one-way FSI analysis to validate the simulations. Then, the influence of internal blade-interactions on the added mass and added damping, as well as the mechanisms, were analyzed.

Flow behaviors in a Kaplan turbine runner with different tip clearances

Tip clearance between the runner blade tip and shroud in a Kaplan turbine is inevitable, and the tip leakage flow (TLF) and tip leakage vortex (TLV) induced by the tip clearance have a considerable effect on the flow behaviors. To reveal the effect of the tip clearance on the flow characteristics, based on the Reynolds time-averaged Navier-Stokes (N-S) equation and the shear stress transfer (SST) k-ω turbulence model, the three-dimensional turbulence flow in a Kaplan turbine is simulated using ANSYS CFX. Meanwhile, the flow laws in the tip clearance are emphatically analyzed and summarized. Results show with the increase of the tip clearance, the negative pressure region in the blade suction side (SS) middle, the SS near the blade tip and the blade tip becomes more and more obvious. In the meantime, the flow behaviors on the blade pressure side (PS) are relatively stable, and the flow separation on the SS near blade tip merges. The larger the tip clearance is, the more obvious the flow separation phenomenon displays. In addition, the TLV is a spatial three-dimensional spiral structure formed by the entrainment effect of the TLF and main flow, and as the tip clearance increases, the TLV becomes more obvious.

An Indirect Measurement Methodology to Identify Load Fluctuations on Axial Turbine Runner Blades.

Smooth integration of intermittent energy sources, such as solar and wind power, into the electrical grid induces new operating conditions of the hydraulic turbine by increasing the off-design operations, start/stops, and load variations. Therefore, hydraulic turbines are subject to unstable flow conditions and unfavorable load fluctuations. Predicting load fluctuations on the runner using indirect measurements can allow for optimized operations of the turbine units, increase turbine refurbishment time intervals, and avoid structural failures in extreme cases. This paper investigates an experimental methodology to assess and predict the flow condition and load fluctuations on a Kaplan turbine runner at several steady-state operations by performing measurements on the shaft in the rotating and stationary frame of references. This unit is instrumented with several transducers such as miniature pressure transducers, strain gages, and proximity probes. The results show that for any propeller curve of a Kaplan turbine, the guide vane opening corresponding to the minimum pressure and strain fluctuations on the runner blade can be obtained by axial, torsion, and bending measurements on the shaft. Torsion measurements on the shaft could support index-testing in Kaplan turbines particularly for updating the cam-curve during the unit operation. Furthermore, a signature of every phenomenon observed on the runner blade signals, e.g., runner frequency, rotating vortex rope components, and rotor-stator interaction, is found in the data obtained from the shaft.

Unsteady multi-phase cavitation analysis on the effect of anti-cavity fin installed on a Kaplan turbine runner

Abstract The tip leakage cavitation phenomenon observed in axial-flow type turbines is one of the major causes of blade tip erosion. This study is focused on the Kaplan turbine cavitation occurring at the tip clearance gap between the blade tip and the stationary shroud casing. An unsteady multi-phase cavitation numerical model is studied on a three-dimensional real scale turbine model for five on-cam conditions. The tip leakage cavitation appeared for the optimum cam condition and at high flow rates. The installation of an Anti-Cavity Fin (ACF) on the suction side along the runner blade tip is investigated for its cavitation mitigation functionality. The hydraulic performance, blade loading distribution, vapor volume fraction and tip leakage flow are compared between the blades with and without an ACF. Detailed flow physics on the formation of Tip Leakage Vortex (TLV) and cavitation zones for three on-cam conditions oriented in high flow rates are also presented. The ACF is shown to be effective in decreasing the cavitation intensity at the leading edge without altering the turbine hydraulic performance. A modification of ACF shape at the trailing edge is suggested to avoid damage to the turbine blade and the ACF.

Static and dynamic computational analysis of Kaplan turbine runner by varying blade profile

Utilization of hydro-power as a renewable energy source is now of prime importance in the world. Hydropower energy is available in abundance as a renewable source. For run-of river, low head reaction type Kaplan turbines mostly used. In this paper, a parametric study has been conducted on a complex geometry of Kaplan blade through static and dynamic computational analysis by varying the blade profile at different angles in the CAD model. Blade geometry surface and design were developed in Creo using the coordinate point system on the blade.Further blade profiles were analyzed to check and compare the output results. Results show that by changing the blade profile geometry, CAD models can be improved using the computational techniques. Consequences obtained were validated with the experimental/operational data and then four different blade profiles were developed. Research consequences showed improvement in the power output of the turbine.

Fluid added polar inertia and damping for the torsional vibration of a Kaplan turbine model runner considering multiple perturbations

A water turbine runner is exposed to several perturbation sources with different frequencies, phases, and amplitudes both at the design and off-design operations. Rotor-stator interaction, cavitation, rotating vortex rope, and blade trailing edge vortices are examples of such perturbations which can disturb the runner. The rotor dynamic coefficients require being determined to perform a reliable dynamic analysis. Fluid added inertia, damping, and stiffness have previously been investigated for individual perturbation frequencies for the torsional vibration of a Kaplan turbine model runner. However, a number of perturbation sources mostly take place simultaneously and alter the dynamics of the runner. Soltani et al. [1] have evaluated the torsional added parameters for a Kaplan turbine runner using numerical simulations considering single perturbation frequency. In the present work, the fluid added parameters are assessed in the presence of multiple perturbation sources. A similar methodology is used. A single-degree-of-freedom (SDOF) model for the dynamic model and unsteady Reynolds-averaged Navier–Stokes approach for the flow simulations are assumed. Perturbations with different frequencies are applied to the rotational speed of the runner to determine the fluid added parameters for the torsional vibration. A number of previously investigated frequencies are chosen and their combinations are investigated. In addition, two different phase shifts are considered between the applied perturbations to study the effect of phase. Two more test cases with higher perturbation amplitude are also conducted to investigate its influence on the fluid added inertia and damping. The results are compared with the previous study and the interaction of multiple perturbations on the added parameters is investigated.

CFD Analysis of Kaplan Turbine Runner for Micro-hydropower

CFD Analysis of Kaplan Turbine Runner for Micro-hydropower

Numerical Predictions of Cavitating Flow around a Marine Propeller and Kaplan Turbine Runner with Calibrated Cavitation Models

Numerical Predictions of Cavitating Flow around a Marine Propeller and Kaplan Turbine Runner with Calibrated Cavitation Models

Lifetime estimations of the operating mechanism of Kaplan turbine runner blades

Lifetime estimations of the operating mechanism of Kaplan turbine runner blades

Design and Velocity Distribution of Runner Blade of Kaplan Turbine Using CFD (Computer Fluid Dynamic) for Small Hydroelectric Power Plant

Procedures for designing runner of Kaplan water turbine based on the specific conditions in the water potential of the area to be placed, and assessed on the terms of the theoretical analysis and engineering. The main objective of this study was to determine the main characteristics of runners, namely suction head, water flow, and the hydraulic forces that occur when the turbine operates. Modern software for engineering such as computational fulid dynamics (CFD) is used to predict the flow of fluid passing through the runner and Computer Aided Engineering (CAE) to verify the design with Finite Element Analisys (FEA). Kaplan turbine runner is designed to place the suction head low and as an option for power generation in Galih Pakuan isolated from Ciwidey area and has not been electricity. The available head and flow rate for turbine are 8 m and 0,3 m3/sec in this site. The output power is 20kW estimated and turbine speed is 900 rpm, In designing blade, blade element theories are the main theories of blade parameter calculation. This paper selecting airfoil shape of the blade from Gottingen (GOE) series and modelling the exact airfoil geometry by using Airfoil.com software.

Analyzing hydro abrasive erosion in Kaplan turbine: A case study from India

Sediment flow through hydro turbine causes erosion of hydraulic components resulting in drop of turbine efficiency, particularly in hydropower plants of the Himalayan region. The measurement of erosion and monitoring of sediment flow in turbine are major concerns in erosion study. Attempts have been made to study erosion mainly in Pelton and Francis turbines. In this study, a simple and effective method has been presented to measure erosion in a Kaplan turbine of a run-of-river scheme Chilla hydropower plant in foothills of Himalaya. Recent techniques were used to measure sediment parameters like concentration, size, shape and mineral content. A standard erosion model is applied to estimate the erosion in Kaplan turbine blade, runner chamber and draft tube cone. A calibration factor has been proposed to apply the erosion model for site specific conditions. It has been found that the outer trailing edges of the turbine blade and upper runner chamber are most erosion prone zones. Sediment analysis revealed that effective operation can reduce erosion in turbine components. The estimated erosion values from model are found to be consistent with measured values. Finally, suggestions for design improvements and effective operation of erosion affected hydropower plants are given.

Repair Welding Methodology for the Glasses of the Kaplan Turbine Runner at the Hydro Power Plant Djerdap 1

Vertical Kaplan turbines, manufactured in Russia and with nominal power of 200 MW, have been installed in 6 hydroelectric generating units at hydro power plant Djerdap 1. Hydroelectric generating sets have been designed for the service life of 40 years due to structural solutions and limited possibilities of performing periodic inspections and state analyses.During the rehabilitation of the hydroelectric generating sets, non-destructive tests were performed on all components and structures in order to complete state analysis. In this paper the damages and methodology of repair welding for damaged glasses, which are the integral part of the kinematic system of runner blades, are presented.

Generation of a multiparameter family of surfaces of the Kaplan turbine runner blade prior to shape optimization

Some approach for the creation is proposed of a multiparameter family of surfaces of runner blade for the Kaplan turbine to find an optimal form by varying the initial prototype of the blade surface.