Use of a model turbine to investigate the high striking risk of fish with tidal and oceanic current turbine blades under slow rotational speed

2020 ◽  
Vol 37 ◽  
pp. 100634 ◽  
Author(s):  
Takero Yoshida ◽  
Jinxin Zhou ◽  
Sanggyu Park ◽  
Hiroaki Muto ◽  
Daisuke Kitazawa
Keyword(s):  
Rotational Speed ◽  
Turbine Blades ◽  
Oceanic Current ◽  
Current Turbine

scholarly journals Model of a Wind Turbine with Variable Blade Angle

2021 ◽  
Vol 25 (1) ◽  
pp. 41-48
Author(s):  
Stanisław Chudzik
Keyword(s):  
Optimal Control ◽  
Wind Turbine ◽  
Rotational Speed ◽  
Power Plants ◽  
Turbine Blades ◽  
Wind Farms ◽  
Blade Angle ◽  
Battery Cell ◽  
General Belief ◽  
Wind Speeds

The article presents the results of research into the operation of a model of a wind micropower plant with a variable blade angle. The research was carried out on a miniature model of a measuring stand built for the purpose of carrying out work on pre-developed projects of wind micro power plants. The stand allows to carry out measurements related to the selection of the optimal propeller geometry, as well as the development and testing of algorithms for optimal control of the micropower plant. The physical basics of wind turbine operation and the methods of its optimal control are presented. The results of the performed measurements for the selected propeller blade geometry with the possibility of changing its setting angle are presented. A DC generator with a load with a non-linear characteristic in the form of a Li-Po battery cell was used. The results of operation of a simple MPPT control algorithm are presented. The lack of optimal control systems for the operation of micropower plants is dictated by the general belief that the costs of its production are high in relation to the possible improvement of the efficiency of micropower plants. Moreover, the practical methods of controlling larger wind turbines are not optimal for small and very small turbines. The conducted research focused on determining the possibility of using turbines with variable blade angles depending on its rotational speed. In larger wind farms, changing the blade angle is mainly used to limit the power of the turbine at high wind speeds. In micro wind power plants such solutions are not used for economic reasons. However, the use of a simple mechanism for changing the angle of the blades depending on the rotational speed of the propeller can increase the efficiency of the turbine in a wider range of wind speeds. The small dimensions of the research model allow for quick and cheap development of preliminary prototypes of turbine blades thanks to the possibility of using 3D printing technology.

Heat Transfer in Internal Cooling Channels of Gas Turbine Blades: Buoyancy and Density Ratio Effects

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Mandana S. Saravani ◽  
Nicholas J. DiPasquale ◽  
Saman Beyhaghi ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Rotational Speed ◽  
Turbine Blades ◽  
Density Ratio ◽  
Internal Cooling ◽  
Buoyancy Effect ◽  
First Case ◽  
Buoyancy Forces ◽  
The Impact

The present work investigates the effects of buoyancy and wall heating condition on the thermal performance of a rotating two-pass square channel with smooth walls. The U-bend channel has a square cross section with a hydraulic diameter of 5.08 cm (2 in.). The lengths of the first and second passes are 514 mm and 460 mm, respectively. The turbulent flow entered the channel with Reynolds numbers of up to 34,000. The rotational speed varied from 0 to 600 rpm with rotational numbers up to 0.75. For this study, two approaches were considered for tracking the buoyancy effect on heat transfer. In the first case, the density ratio was set constant, and the rotational speed was varied. In the second case, the density ratio was changed in the stationary case, and the effect of density ratio was discussed. The range of buoyancy number along the channel is 0–6. The objective was to investigate the impact of buoyancy forces on a broader range of rotation number (0–0.75) and buoyancy number scales (0–6), and their combined effects on heat transfer coefficient for a channel with an aspect ratio of 1 : 1. Results showed that increasing the density ratio increased the heat transfer ratio in both stationary and rotational cases. Furthermore, in rotational cases, buoyancy force effects were very significant. Increasing the rotation number induced more buoyancy forces, which led to an enhancement in heat transfer. The buoyancy effect was more visible in the turning region than any other region.

Non-Linear Modeling of Ocean Current Turbine Blades Under Large Deflection

2016 ◽  
Author(s):  
Takuya Suzuki ◽  
Hassan Mahfuz
Keyword(s):  
Large Scale ◽  
Large Deflection ◽  
Turbine Blades ◽  
Structural Response ◽  
Ocean Current ◽  
Hydrodynamic Load ◽  
Linear Modeling ◽  
Non Linear ◽  
The Difference ◽  
Current Turbine

This paper presents a non-linear modeling approach for large-scale ocean current turbine (OCT) blades. During the operation, OCT blades are subjected to a hydrodynamic load that has fluid density 800 times higher than that of air. The fluid load on OCT blades are sufficient to cause large deflection; therefore, a method that couples the blade’s deflection and the hydrodynamic load is required. For this purpose, we developed a non-linear model for turbine blades based on blade element momentum (BEM) theory. The newly developed method considers interplay between blade’s deflection and the hydrodynamic load. In addition, geometric non-linearity is also considered in the analysis, which provides a more accurate prediction of the structural response. For validation purposes, the developed method and a set of existing National Renewable Energy Laboratory (NREL) codes were used to calculate the deflection of the OCT blade. A comparison of flap-wise and edge-wise deflections given by both methods were determined and the results showed a good correlation between the two methods. This comparison was made only for small deflection since NREL codes cannot account for large deflection. In the next step, to investigate the effect of non-linearity, both linear and non-linear analyses were performed for a large-scale OCT blade where deflection was indeed large. In this study, we analyzed a flexible blade made of E-glass/epoxy composite. The difference in deflection was about 11% for the flexible blade since the fluid-structure interaction was significant as the blade deflection was large.

Design and Analysis of Composite Ocean Current Turbine Blades Using NREL Codes

2012 ◽  
Author(s):  
Fang Zhou ◽  
Hassan Mahfuz ◽  
Gabriel M. Alsenas ◽  
Howard P. Hanson
Keyword(s):  
Wind Turbine ◽  
Stress Analysis ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Core Material ◽  
Ocean Current ◽  
Wind Turbine Blades ◽  
Lift And Drag ◽  
Current Turbine ◽  
Core Materials

Ocean current energy is at an early stage of development — a vital component in that is the design and analysis of turbine blades that would be used to generate the power. The ocean current turbine (OCT) is similar in function to wind turbines, capturing energy through the processes of hydrodynamic, rather than aerodynamic, lift or drag. OCT operates on many of the same principles as wind turbines and share similar design philosophies. NREL (National Renewable Energy Laboratory) has extensively investigated the design of wind turbine blades over the years and many codes have been developed. It is meaningful and prudent to take advantage of those codes and use them in the design of OCT blades. Currently available codes such as FoilCheck, PreComp, BModes, AeroDyn, FAST, etc. provides an excellent dynamic analysis of hollow composite wind turbine blades. Since OCT blades have PVC foam as core materials inside the skin, NREL codes could not be used directly. These core materials for the blade were necessary to fulfill the buoyancy requirement at ocean depth. A set of methods was therefore developed to design and analyze OCT blades where most of NREL codes could be utilized. The methods are as follows: DesignFOIL was first used to generate hydrofoil geometry (coordinates), and lift and drag coefficients for selected blade sections. FoilCheck was then used to calculate hydrofoil data for the entire range of ±180°. FoilCheck output files were later used as input for AeroDyn. In the next step, PreComp computed the section properties for the hollow composite OCT blade. Section properties of the core material such as extensional stiffness, flexural rigidity, and torsional rigidity were calculated separately and added to the properties computed by PreComp. Mode shapes and frequencies of OCT blades were computed using BModes. AeroDyn calculated the hydrodynamic lift and drag forces for the hydrofoil sections along the blade. In AeroDyn input file, kinematic viscosity, density and velocity were set to the values of seawater @ 1.05×10−6 m2/sec, 1025 kg/m3, and 1.7 m/s, respectively. Finally, FAST was used to obtain the dynamic response of three-bladed, conventional, horizontal-axis OCT. However, this analysis did not provide any stress calculations. In order to perform stress analysis, NuMAD code developed by Sandia National Laboratory was incorporated in the method. This allowed us to create ANSYS input files. Loads calculated by AeroDyn were then transported to ANSYS and a complete stress analysis was performed. Critical regions of stress concentration were identified — opening up an opportunity for materials failure and fatigue analysis. In summary, coupling of NREL codes, NuMAD, and ANSYS revealed a path way to achieve comprehensive design and analyses of OCT blades.

Machining and Characterization of Double-Helical Grooves on Cylindrical Copper Parts by Wire Electric Discharge Turning

2020 ◽  
Vol 1009 ◽  
pp. 117-122
Author(s):  
Jacob Serah Krupa ◽  
G.L. Samuel
Keyword(s):  
Aspect Ratio ◽  
Electric Discharge ◽  
High Aspect Ratio ◽  
Rotational Speed ◽  
Turbine Blades ◽  
Wire Edm ◽  
Machining Time ◽  
Pitch Distance ◽  
Helical Grooves

In the work, the design and development of a novel Wire-EDM setup with double-wire guide discs is presented. It facilitates sparks to be generated between the workpiece and wire at two locations separated by the helical pitch distance. This sparking causes two helical grooves to be generated simultaneously on the surface of the workpiece when it is given suitable rotational speed and table feed. In this work, machining is carried out on rods of 1.5 mm diameter. Helical groves with helix angles ranging from 35 to 500 were generated and characterized. This method of machining the double helical grooves with a single pass reduces the machining time and eliminates the complexities involved in machining one groove at a time. It was observed that the proposed method is suitable for machining double helical grooves with helix angles in the range of 40 - 50°. The parts produced by the mentioned method can be used as EDM tools for generation of high aspect ratio holes in turbine blades and injection nozzles.

Experimental Friction Damping Characteristic of a Steam Turbine Blade Coupled by Shroud and Snubber at Standstill Set-Up

2012 ◽  
Author(s):  
Jun Wu ◽  
Yonghui Xie ◽  
Di Zhang ◽  
Minghui Zhang
Keyword(s):  
Steam Turbine ◽  
Turbine Blade ◽  
Rotational Speed ◽  
Damping Ratio ◽  
Turbine Blades ◽  
Contact Forces ◽  
Normal Contact ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Steam Turbine Blade

In order to avoid the high cycle fatigue which leads to the failure of turbine blades, friction structural damping has been widely used in turbine blade designs to reduce vibratory stresses by energy dissipation. A method is developed here to analyze the influence of friction structural damping on the vibration characteristics of turbine blades. Vibratory responses of a long steam turbine blade with shroud and snubber are studied. Finite element contact analysis of the steam turbine blades which are modeled in 3-D solid elements is conducted to obtain the normal contact force on the shroud contact surface and snubber contact surface of adjacent blades under five different rotational speeds (2100rpm, 2200rpm, 2413rpm, 2600rpm and 3000rpm). A rig for the tests of non-rotating turbine blade with friction damping structure is built. The normal contact forces of the shroud and snubber are applied to the blade according to numerical results. The response curves and modal damping ratios of the blade under different normal contact forces, which each one is related to a different rotational speed, are obtained. The experimental results show that with increases in rotational speed, modal damping ratio of the blade experiences an increasing period followed by a decreasing period while the resonance amplitude decreases first and then increases when there is only shroud contact. The effects are similar when there are both shroud and snubber contact. The modal damping ratio of the blade is basically identical with that of the uncoupled blade for the rotational speed above 2600rpm. For this range of rotational speed, the resonance frequency increases with the increase of rotational speed, and the changes of the resonance frequency are very trivial.

scholarly journals Current From Currents

2003 ◽  
Vol 125 (02) ◽  
pp. 40-41
Author(s):  
Gayle Ehrenman
Keyword(s):  
Turbine Blades ◽  
Axial Flow ◽  
The United Kingdom ◽  
Sea Current ◽  
Marine Current ◽  
A Site ◽  
The Cost ◽  
Electrical Utilities ◽  
Current Turbine ◽  
A Current

This article discusses that in the quest for renewable energy, the oceans’ tides and flow have gone largely untapped. Companies in the United Kingdom and Canada are trying to harvest the power of sea current through new application of an old technology: turbines. IT Power is using technology from its spin-off company, Marine Current Turbines, also in Hampshire. The technology consists of a pair of axial flow rotors that are roughly 50 to 65 feet in diameter. Each drives a generator via a gearbox, much like a wind turbine. Blue Energy Canada is also working the currents. Its approach differs from that of IT Power in two significant ways: orientation of the turbine blades and their arrangement. A study conducted in 2001 by Triton Consultants, based in Vancouver, BC, on behalf of BC Hydro (one of the largest electrical utilities in Canada), found that the cost to develop a current turbine site is rather high, but the cost of annual power generation would be low. The study considered a site at the Discovery Passage in British Columbia, which it speculated would run 7941-MW Marine Current Turbines spread over roughly 3922 acres.

scholarly journals Numerical Research on the Vortex Center on the Forward-Swept 3-D Wind Turbine Blades at Low Rotational Speed

2018 ◽  
Vol 12 (12) ◽  
pp. 80
Author(s):  
Sutrisno . ◽  
Setyawan Bekti Wibowo ◽  
Sigit Iswahyudi
Keyword(s):  
Wind Turbine ◽  
Rotational Speed ◽  
Cfd Simulation ◽  
Velocity Ratio ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Leading Edge ◽  
Vortex Center ◽  
Wind Turbine Blades ◽  
Horizontal Axis Wind Turbine

This paper studies the CFD simulation of forward three-dimensional (3-D) horizontal axis wind turbine (HAWT) blades. Using logarithmic grid and Q-criterion to learn the vortex dynamics around the blades at low rotational speed. The computational fluid dynamics (CFD) simulation uses Q-criterion to probe vortices and logarithmic grid to emphasize the micro-gridding effect of the turbulent boundary layer. The visualization & measurement of the simulation results give the coefficient of pressure (Cp). For forward 3-D wind turbine blade, at low rotational speed, the strongly accelerated laminar region surrounds the lower blade, and the decelerated tip blade region coalesce each other give rise to a reverse limiting streamline, eroding the laminar region further until a little is left on the tip of the blade. The "reverse limiting streamline" grows inward radially, the area is narrowing closing to the leading edge of the blade tip. The second side of the rolled-up vortex appears the velocity ratio (Uc/Ulocal) of the second vortices are higher than the main vortex cores. For radius R=1.547 m, U=12 m/s, at 210 RPM, CL and CD values reach a maximum with fully laminar tip conditions. While at 120 RPM, the CL and CD values reach a minimum in the absence of laminar tips. The results show the detailed vortex dynamic pattern surround the blades, give more understanding to design laminar 3-D blade toward a noiseless wind turbine system.

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