Some design guidelines to adapt a Darrieus vertical axis turbine for use in hydrokinetic applications (original) (raw)
Related papers
Journal of Renewable and Sustainable Energy, 2011
The hydrodynamic performance of horizontal axis hydrokinetic turbines (HAHkTs) under different turbine geometries and flow conditions is discussed. Hydrokinetic turbines are a class of zero-head hydropower systems which utilize kinetic energy of flowing water to drive a generator. However, such turbines very often suffer from low-efficiency which is primarily due to its operation in a low tip-speed ratio (4) regime. This makes the design of a HAHkT a challenging task. A detailed computational fluid dynamics study was performed using the k-x shear stress transport turbulence model to examine the effect of various parameters like tip-speed ratio, solidity, angle of attack, and number of blades on the performance HAHkTs having power capacities of $12 kW. For this purpose, a three-dimensional numerical model was developed and validated with experimental data. The numerical studies estimate optimum turbine solidity and blade numbers that produce maximum power coefficient at a given tip speed ratio. Simulations were also performed to observe the axial velocity ratios at the turbine rotor downstream for different tip speed ratios which provide quantitative details of energy loss suffered by each turbine at an ambient flow condition. The velocity distribution provides confirmation of the stall-delay phenomenon due to the effect of rotation of the turbine and a further verification of optimum tip speed ratio corresponding to maximum power coefficient obtained from the solidity analysis. V
Design Considerations of a Straight Bladed Darrieus Rotor for River Current Turbines
ISIE, 2006
Hydrokinetic turbines convert kinetic energy of moving river or tide water into electrical energy. In this work, design considerations of river current turbines are discussed with emphasis on straight bladed Darrieus rotors. Fluid dynamic analysis is carried out to predict the performance of the rotor. Discussions on a broad range of physical and operational conditions that may impact the design scenario are also presented. In addition, a systematic design procedure along with supporting information that would aid various decision making steps are outlined and illustrated by a design example. Finally, the scope for further work is highlighted.
Design and Hydrodynamic Performance of a Horizontal Axis Hydrokinetic Turbine
International Journal of Automotive and Mechanical Engineering
Marine energy is gaining more and more interest in recent years and, in comparison to fossil energy, is very attractive due to predictable energy output, renewable and sustainable, the Horizontal Axis Hydrokinetic Turbine (HAHT) is one of the most innovative energy systems that allow transforms the kinetic energy into electricity. This work presents a new series of hydrofoil sections, named here NTSXX20, and was designed to work at different turbine functioning requirement. These hydrofoils have excellent hydrodynamic characteristics at the operating Reynolds number. The design of the turbine has been done utilising XFLR5 code and QBlade which is a Blade-Element Momentum solver with a blade design feature. Tidal current turbine has been able to capture about 50% from TSR range of 5 to 9 with maximum CPower of 51 % at TSR=6,5. The hydrodynamics performance for the CFD cases was presented and was employed to explain the complete response of the turbine.
AERODYNAMIC PROFILES FOR APPLICATIONS IN HORIZONTAL AXIS HYDROKINETIC TURBINES
IAEME, 2019
Research in aerodynamics has allowed the creation of different profiles for certain applications, reliably predicting the lift and drag coefficients by means of simulations or experimental methods. In the field of wind and hydraulic power generation, they have developed turbine rotors with improved performance and greater efficiency; several researchers have evaluated the influence of the use of aero profiles on the operation of hydrokinetic turbines through simulations and experimental tests. The main objective of this review is to show the reader the importance of the proper choice of an aero profile and its influence for the calculation during the design of rotor blades and the performance of hydrokinetic turbines.
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
Development of horizontal axis hydrokinetic turbine using experimental and numerical approaches
2020
Hydrokinetic energy conversion systems (HECSs) are emerging as viable solutions for harnessing the kinetic energy in river streams and tidal currents due to their low operating head and flexible mobility. This study is focused on the experimental and numerical aspects of developing an axial HECS for applications with low head ranges and limited operational space. In Part I, blade element momentum (BEM) and neural network (NN) models were developed and coupled to overcome the BEM's inherent convergence issues which hinder the blade design process. The NNs were also used as a multivariate interpolation tool to estimate the blade hydrodynamic characteristics required by the BEM model. The BEM-NN model was able to operate without convergence problems and provide accurate results even at high tip speed ratios. In Part II, an experimental setup was developed and tested in a water tunnel. The effects of flow velocity, pitch angle, number of blades, number of rotors, and duct reducer were investigated. The performance was improved as rotors were added to the system. However, as rotors added, their contribution was less. Significant performance improvement was observed after incorporating a duct reducer. In Part III, a computational fluid dynamics (CFD) simulation was conducted to derive the optimum design criteria for the multi-turbine system. Solidity, blockage, and their interactive effects were studied. The system configuration was altered, then its performance and flow characteristics were investigated. The experimental setup was upgraded to allow for blockage correction. Particle image velocimetry was used to investigate the wake velocity profiles and validate the CFD model. The flow characteristics and their effects on the turbines performance were analyzed.
Environmental Progress & Sustainable Energy, 2016
The main objective of this paper is to achieve a very high lift rotor to take the maximum advantage of the kinetic energy of a slow velocity water flow, which belongs to a lowland river type. Low speed flux and lack of depth are the main obstacles in hydrokinetic operation. The use of a high lift aerodynamic profile and the gain of the rotor number of blades serve to accomplish the task. This work presents the fluid dynamic design for an axial hydrokinetic turbine rotor, studied in a three-dimensional (3-D) numerical simulation by means of Computational Fluid Dynamics (CFD). The use of CFD techniques avoids some physical model assays. For the hydrokinetic turbine rotor design, first a one-dimensional (1-D) theoretical design was carried out, starting with the selection of a suitable airfoil profile to create the hydrofoil blade. Then, the 3-D rotor geometry was defined and studied 2 carefully by means of CFD, in order to check its hydrodynamic behaviour, i.e., lift and drag, streamline velocities and pressure fields. The CFD results were obtained using an open CFD code (Kratos). Novelty: Despite hydrokinetic energy conversion is not a new technic; the application in a free water stream is becoming popular in the present. Most of the advances in this field involves oceanographic tides, relegating river flow usage to a very few studies. A very small part of these ambit concerns about a riverbed location of the hydrokinetic turbine, working in axial flow mode. Classical 3 bladed rotors in a drag operation enclose the advances in the field. This work aims to present the feasibility study of an 8 bladed hydrokinetic turbine rotor, improved by a high lift hydrodynamic profile.
Design and critical performance evaluation of horizontal axis hydrokinetic turbines
2010
I wish to express my deep sense of gratitude and sincere appreciation to my advisor Prof. Arindam Banerjee who guided me with diligence and patience throughout my thesis. He has always been extremely helpful, encouraging and a constant source of motivation. I would like to thank my committee members Prof. Rajiv Mishra, Prof. K. Chandrashekhara and Prof. Jonathan Kimball for their support and cooperation. In addition, I express my sincere appreciation to Prof. Rajiv Mishra for providing me with helpful suggestions throughout the project. I acknowledge the financial support from the Energy Research and Development Center (ERDC) of Missouri S&T and Office of Naval Research which made this work possible. I would also like to acknowledge my fellow members of Turbulent Mixing and Alternative Energetics Laboratory: Aaron, Raghu, Tim, Nitin, Varun and Pamela for sharing useful thoughts and engaging in fruitful discussions over the duration of this work. Special thanks to Ms. Katherine Wagner and Ms. Vicki Hudgins for their help at various stages of my MS program and with my thesis. I would also like to thank IT helpdesk for the software support function. Last but not the least, I would like to thank my mother, my elder brother, my grandmother and all my family members for their constant support, cooperation and love; without them none of this would have been possible. v
Design of a hydrokinetic turbine
WIT Transactions on Ecology and the Environment, 2015
Hydrokinetic turbine power production depends on the interaction between the rotor and water. Therefore, an optimum geometry of the rotor must be designed and constructed to capture the maximum water energy and convert it into a usable energy. The steps involved in the design and numerical simulation of a small horizontal axis hydrokinetic turbine rotor are presented based on the same incompressible flow techniques used for designing wind turbines. Three blades of a 1 Hp (746 W) prototype hydrokinetic turbine were designed for a water velocity of 1.5 m/s with a tip speed ratio of 6.325, an angle of attack of 5 • and 0 • as the pitch angle; in order to obtain the maximum power coefficient of the turbine. This coefficient was 0.4382, near the Betz limit. S822 airfoil was used to generate the coordinates of the blade. CFD simulation was carried out using Ansys CFX to estimate the performance of the blade design. Furthermore, FEM was successfully used for stress calculations on turbine blades under the influence of centrifugal and hydrodynamic loading. The designed hydrokinetic turbine can be used for pico hydro generation in rural communities non-connected to electricity services through the national interconnected electric system, due to its simple structure, and low cost of initial investment. Additionally, it can be locally manufactured, the environmental impact is negligible, since large dams are not involved, and the schemes can be managed and maintained by the consumer.
Design and Optimization of a Multi-Element Hydrofoil for a Horizontal-Axis Hydrokinetic Turbine
Energies, 2019
Hydrokinetic turbines are devices that harness the power from moving water of rivers, canals, and artificial currents without the construction of a dam. The design optimization of the rotor is the most important stage to maximize the power production. The rotor is designed to convert the kinetic energy of the water current into mechanical rotation energy, which is subsequently converted into electrical energy by an electric generator. The rotor blades are critical components that have a large impact on the performance of the turbine. These elements are designed from traditional hydrodynamic profiles (hydrofoils), to directly interact with the water current. Operational effectiveness of the hydrokinetic turbines depends on their performance, which is measured by using the ratio between the lift coefficient (CL) and the drag coefficient (CD) of the selected hydrofoil. High lift forces at low flow rates are required in the design of the blades; therefore, the use of multi-element hydro...