Design and performance of very low head water turbines using a surface vorticity model algorithm (original) (raw)
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Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019
Very low head (VLH) axial hydro turbines are efficient turbomachinery to harness energy from tidal or river currents and increase renewable energy penetration in the world's electric power generation. In this paper, the initial design of a VLH turbine with high pitch blade is optimized. The class function/shape function transformation method is applied along with a coupling of XFOIL with a MATLAB code to find optimum blade profiles with minimum drag-to-lift ratio. SST k-ω turbulence model is implemented to solve three-dimensional (3D) continuity and RANS equations by considering homogeneous multiphase model with standard free surface flow. The numerical results are validated against available experimental measurements, and the optimization results are discussed. The numerical results indicated that efficiency and power of the VLH turbine at the design point increased by 2.4% and 7.7 kW, respectively. Analyzing pressure distribution on suction and pressure sides of runner blades showed no occurrence of cavitation in operating condition of the turbine.
Runner profile optimisation of gravitational vortex water turbine
International Journal of Electrical and Computer Engineering (IJECE)
This study discusses the numerical optimisation and performance testing of the turbine runner profile for the designed gravitational water vortex turbine. The initial design of the turbine runner is optimised using a surface vorticity algorithm coded in MATLAB to obtain the optimal stagger angle. Design validation is carried out using computational fluid dynamics (CFD) Ansys CFX to determine the performance of the turbine runner with the turbulent shear stress transport model. The CFD analysis shows that by optimising the design, the water turbine efficiency increases by about 2.6%. The prototype of the vortex turbine runner is made using a 3D printing machine with resin material. It is later tested in a laboratory-scale experiment that measures the shaft power, shaft torque and turbine efficiency in correspondence with rotational speeds varying from 150 to 650 rpm. Experiment results validate that the optimised runner has an efficiency of 45.3% or about 14% greater than the initial...
Hydrodynamic and performance of low power turbines: conception, modelling and experimental tests
2010
The present work comprises a research about hydraulic machines with the aim of optimization and the selection of adequate turbines of low power for exploitation of an available energy still unexplored in water supply systems based on analyses of 3D hydrodynamic flows and on characteristic curves which lead to the best efficiency point. The analysis is carried out based on non-dimensional parameters (i.e., discharge, head, efficiency, runner speed and mechanical power) in order to be possible comparisons. Mathematical models based on the physical principles, associated to the development of volumetric and rotordynamic machines, are developed. New turbines are suggested, which are based on similar theory among turbo machines based on applications in hydraulic systems with guarantee discharge and available head. The hydrodynamic fluid mechanical analysis requires the use of complex advanced models (CFD) which apply the equations of Navier-Stokes by using mathematical models of conservation laws, for the study of the turbulent flow behaviour. To determine the correlation between the flow velocity and pressure fields, the k-ε model, is used in this research. Many turbines are evaluated (i.e., positive displacement (PD), pump as turbine (PAT), propeller with volute at inlet, four and five blades tubular propellers) and sensitivity analyses, to the best configurations, as well as comparisons between performance curves and experimental tests. Results are presented with the appropriate range variation for each turbine type and application.
Performance Analysis of a Low Head Water Vortex Turbine
MIST journal of science and technology, 2021
A small hydropower plant is an environment-friendly renewable energy technology. The run-of-river type gravitational water vortex turbine can be designed to produce electricity at sites with low water heads. In this study, an experimental investigation was undertaken on this type of turbine with a water tank and a runner which is connected to a shaft. At the end of the shaft, a rope brake was attached to measure the output power, torque and overall efficiency of the vortex turbine by varying flow rates. The designed vortex turbine can achieve an overall efficiency of 52.67%. The experimental results were validated with available data in the literature and theories associated with the turbine. The results also showed that the flow rate plays a vital role in generating power, torque as well as overall efficiency. The project was completed using local resources and technologies. Moreover, as water is used as the input power, this project is eco-friendly which has no adverse effect on the environment.
World Academy of Science, Engineering and Technology, International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering, 2012
This paper presents a numerical analysis of the performance of a five-bladed Darrieus vertical-axis water turbine, based on the NACA 0025 blade profile, for both bare nd shrouded configurations. A complete campaign of 2-D simulati ons, performed for several values of tip speed ratio and based on RANS unsteady calculations, has been performed to obtain the roto r t rque and power curves. Also the effect of a NACA-shaped central hy drofoil has been investigated, with the aim of evaluating the impact of a solid blockage on the performance of the shrouded rotor c onfiguration. The beneficial effect of the shroud on rotor overal l performances has clearly been evidenced, while the adoption of t he central hydrofoil has proved to be detrimental, being the r esulting flow slow down (due to the presence of the obstacle) much hig er with respect to the flow acceleration (due to the solid blockage eff ct). Keywords—CFD, vertical axis water turbine, shroud, NACA 0025
Optimization study on an ultra-low head bulb hydro turbine
Procceedings of the 24th ABCM International Congress of Mechanical Engineering, 2017
The increase of efficiency of a turbomachine requires a behavior analysis of the flow on its hydromechanical components, in a global way. For a proposal of modification in the profile of the components on a conceptual machine, aiming its optimization, it is necessary to survey into the reason of the possible shortcomings and, finally, to present arguments for their optimization. The use of Computational Fluid Dynamics (CFD) tools are widely used in these researches. Consolidated axial turbines, in general, presents very significant efficiencies, however, machines that operate under special conditions, such as turbines for ultra-low heads condition (0.5 meters to 5.0 meters), are still under development, opening space for research on performance improvements. This work presents an analysis based on the results obtained by computational study through CFD, in order to evaluate an ultra-low head turbine model, proposing the optimization of its performance. The analysis discussed in this paper suggested the exclusion of the original draft tube system, in order to verify the behavior of the fluid flow. This modification resulted in a slight improvement of the efficiency.
Background:The study of the optimization of horizontal axis hydrokinetic turbineperformances using computational fluid dynamics (CFD), creates awareness on the recent development in renewable energy industries and enhanced the output power of the Hydrokinetic power plant. In this work. the effect of TSR and chord length was investigated using CFD approach and. the results shows that power coefficient (C p) depends on TSR and slightly affected by chord length. Materials and Method:A three dimensional CFD analysis performed using ANSYS CFX 15.0 and SolidWorks as Preprocessor to draw the rotor, boundary conditions were created using the pre-processing tool solid-works, Hydrofoil SG-6043 was chosen for the simulation and mesh was created using structured quadrilateral cells around the hydrofoils. The computational domain was assumed to be sufficiently large compared to the chord length to enable larger area of flow visualization around the hydrofoil. A finer mesh was applied on the vicinity of the hydrofoil to obtain better flow characteristics and flow orientation very near to surface. Quadrilateral elements were used to mesh the entire geometry to ensure uniform aspect ratios of cells across the domain. Results: As the rotational speed increases from root to tip of a blade, the flow angle decreases andas solidity increase from 0.084 to 0.127 there was a corresponding increase of C p from 0.112 to 0.284 implying strong influence of solidity on horizontal axis hydrokinetic turbine performances. From analysis the results of the optimization performed shows that a C p value of 0.45 achievable for a variable chord rotor of 1.0m at appropriate combination of turbine parameters. Conclusion: Hydrodynamic analysis and optimization shows that the performance of hydrokinetic turbine can be maximized by choosing the right combination of design variables. Secondly, the three-dimensional results for optimum design suggested a strong dependence of maximum C P on TSR when different turbine geometries are being considered. It was also observed that, Increase in turbine solidity results in increased C P under the entire operating range of TSR studied with maximum C P observed in lower TSR
Experimental and Numerical Studies on the Influence of Blade Number in a Small Water Turbine
Energies
This paper demonstrates the procedure of blade adjustment in a Kaplan-type water turbine, based on calculations of the flow system. The geometrical adjustment of a twisted blade with varying chord length is described in the study. Computational fluid dynamics (CFD) analysis was used to characterise aerofoil and turbine performance. Furthermore, two turbines, with a different number of blades, were designed, manufactured, and tested experimentally. The numerical model results were then compared with the experimental data. The studies were carried out with different rotational velocities and different stator blade incidence angles. The paper shows a comparison of the turbine efficiencies that were assessed, using numerical and experimental methods, of a flow system with four- and five-bladed rotors. The numerical model results matched up well with those of the experimental study. The efficiency of the proposed turbines reached up to 72% and 84% for four-bladed and five-bladed designs,...
IJOCE (International Journal of Offshore and Coastal Engineering), 2022
The issue of renewable and eco-friendly energy has become the focus of research in several countries to encourage eco-friendly alternative energy. One of them is by using turbines to produce electrical energy. Vertical Axis Water Turbine (VAWT) can be an exciting research object because it has various advantages. VAWT has a simpler structure, can move at relatively slow currents and is famous for its tendency to move regardless of the water flow directions. In this study, the experimental turbine from secondary data numerically simulates using the Computational Fluid Dynamics (CFD) method with the help of ANSYS V18.1 software. The Gorlov turbine model is manufactured in 3 dimensions under steady-state flow conditions. Validation is carried out after obtaining numerical results with the mean error rate being less than 10%. The variables in this research are the thickness of hydrofoil using NACA 0010, NACA 0016, NACA 0020, and variations in inclination angle of the blade for 25 0 and 60 0. After comparing the simulation results in the form of torque values is done, it is shown that the best turbine performance is given by water turbine using NACA 0016 with 60 0 of inclination angle.
IOP Conference Series: Earth and Environmental Science, 2019
This article presents the results of the study on the effect of blade number and turbine baffle plates on the efficiency of a free-vortex water turbine. The laboratory experimentation performed to determine the power generation efficiency. The 2 to 7 blade water turbines were built and tested to find the most appropriate number of blades, and the result showed the 5 blade turbine being appropriate because it yields the highest torque from receiving impact from water flow. Next, the baffle plates were designed and attached to the top and bottom of the turbine blades. Four different sizes of space from 25% to 100% of the curve area around the blades were used. Experiments were carried out at the water flow rates of 0.04 to 0.06m3/s. The finding showed the 50% proportion of the curve area being most appropriate, and the blades installed with top and bottom baffle plates had the highest efficiency of 43.83%, which was 6.59% higher than without baffle plates. It was also found that when the water flow rate increased, the system efficiency became higher.