• Title/Summary/Keyword: Hydrokinetic

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Evaluation of hydrokinetic energy potentials of selected rivers in Kwara State, Nigeria

  • Adeogun, Adeniyu Ganiyu;Ganiyu, Habeeb Oladimeji;Ladokun, Laniyi Laniran;Ibitoye, Biliyamin Adeoye
    • Environmental Engineering Research
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    • v.25 no.3
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    • pp.267-273
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    • 2020
  • This Hydrokinetic energy system is the process of extracting energy from rivers, canals and others sources to generate small scale electrical energy for decentralized usage. This study investigates the application of Soil and Water Assessment Tool (SWAT) in Geographical Information System (GIS) environment to evaluate the theoretical hydrokinetic energy potentials of selected Rivers (Asa, Awun and Oyun) all in Asa watershed, Kwara state, Nigeria. SWAT was interfaced with an open source GIS system to predict the flow and other hydrological parameters of the sub-basins. The model was calibrated and validated using observed stream flow data. Calibrated flow results were used in conjunction with other parameters to compute the theoretical hydrokinetic energy potentials of the Rivers. Results showed a good correlation between the observed flow and the simulated flow, indicated by ash Sutcliffe Efficiency (NSE) and R2 of 0.76 and 0.85, respectively for calibration period, and NSE and R2 of 0.70 and 0.74, respectively for the validation period. Also, it was observed that highest potential of 154.82 MW was obtained along River Awun while the lowest potential of 41.63 MW was obtained along River Asa. The energy potentials obtained could be harnessed and deployed to the communities around the watershed for their energy needs.

Design, test and numerical simulation of a low-speed horizontal axis hydrokinetic turbine

  • Tian, Wenlong;Mao, Zhaoyong;Ding, Hao
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.6
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    • pp.782-793
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    • 2018
  • A small-scale horizontal axis hydrokinetic turbine is designed, manufactured and studied both experimentally and numerically in this study. The turbine is expected to work in most of China's sea areas where the ocean current velocity is low and to supply electricity for remote islands. To improve the efficiency of the turbine at low flow velocities, a magnetic coupling is used for the non-contacting transmission of the rotor torque. A prototype is manufactured and tested in a towing tank. The experimental results show that the turbine is characterized by a cut-in velocity of 0.25 m/s and a maximum power coefficient of 0.33, proving the feasibility of using magnetic couplings to reduce the resistive torque in the transmission parts. Three dimensional Computational Fluid Dynamics (CFD) simulations, which are based on the Reynolds Averaged Navier-Stokes (RANS) equations, are then performed to evaluate the performance of the rotor both at transient and steady state.

Analysis of Permanent Magnet Synchronous Generator for Vortex Induced Vibration Hydrokinetic Energy Applications Based on Analytical Magnetic Field Calculations

  • Choi, Jang-Young;Shin, Hyun-Jae;Choi, Jong-Su;Hong, Sup;Yeu, Tae-Kyeong;Kim, Hyung-Woo
    • Journal of Magnetics
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    • v.17 no.1
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    • pp.19-26
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    • 2012
  • This paper deals with the performance analysis and estimation of the electrical parameters of a permanent magnet synchronous generator (PMSG) for hydrokinetic energy conversion applications using vortex induced vibration (VIV). The analytical solutions for the magnetic fields produced by permanent magnets (PMs) and stator winding currents are obtained using a 2D polar coordinate system and a magnetic vector potential. An analytical expression for the 2D permeance is also derived, which takes into account stator skew effects. Based on these magnetic field solutions and the 2D permeance function, electrical circuit parameters such as the backemf constant and the air-gap inductance are obtained analytically. The performances of the PMSG are investigated using the estimated electrical circuit parameters and an equivalent circuit (EC). All analytical results are validated extensively using 2D finite element (FE) analyses. Experimental measurements for parameters such as the back-emf and inductance are also presented to confirm the analyses.

SCANNING ELECTRON MICROSCOPIC STUDY OF IMPLANT SURFACE AFTER Er,Cr:YSGG LASER IRRADIATION (Er,Cr:YSGG 레이저를 조사한 임플란트 표면의 주사전자현미경적 연구)

  • Jo, Pil-Kwy;Min, Seung-Ki;Kwon, Kyung-Hwan;Kim, Young-Jo
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.28 no.5
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    • pp.454-469
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    • 2006
  • Today, there is considerable evidence to support a cause-effect relationship between microbial colonization and the pathogenesis of implant failures. The presence of bacteria on implant surfaces may result in an inflammation of the peri-implant mucosa, and, if left untreated, it may lead to a progressive destruction of alveolar bone supporting the implant, which has been named as peri-impantitis. Several maintenance regimens and treatment strategies for failing implants have been suggested. Recently, in addition to these conventional tools, the use of different laser systems has also been proposed for treatment of peri-implant infections. As lasers can perform excellent tissue ablation with high bactericidal and detoxification effects, they are expected to be one of the most promising new technical modalities for treatment of failing implants. It is introduced that Er,Cr:YSGG laser, operating at 2780nm, ablates tissue by a hydrokinetic process that prevents temperature rise. We studied the change of the titanium implant surface under scanning electron microscopy after using Er,Cr:YSGG laser at various energies, irradiation time. In this study, Er,Cr:YSGG laser irradiation of implant fixture showed different effects according to implant surface. Er,Cr:YSGG laser in TPS surface with RBM not alter the implant surface under power setting of 4 Watt(W) and irradiation time of 30sec. But in TPS surface with $Ca_3P$ coating alter above power setting of 2W and irradiation time of 10sec. TPS surface with RBM showed microfracture in 4W, 30sec and TPS surface with $Ca_3P$ coating showed destruction of fine crystalline structure, melting in excess of 2W, 10sec. We concluded that proper power setting, air, water of each implant surface must be investigated and implant surface must be irradiated under the damaged extent.

A Comparison of Performance of Six and Twelve-Blade Vane Tidal Turbines between Single and Double Blade-row Types (블레이드 열의 배치에 따른 베인형 조류 수차의 성능 비교)

  • Nguyen, M.H.;Kim, J.H.;Kim, B.K.;Yang, C.
    • The KSFM Journal of Fluid Machinery
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    • v.18 no.1
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    • pp.51-58
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    • 2015
  • This paper presents a study on Vane Tidal Turbine (VTT) focusing on analysis of two types of blade arrangement originated from the previous studies where the original design was examined and performance-tested for different numbers of blades (six, eight and twelve). Compared to conventional tidal turbines, VTT has several special features and potential advantages which have been being thoroughly developed. The purpose of this study is to analyze VTT's capability of extracting and converting the hydrokinetic energy of tidal currents into electricity at given arrangement of blades (single and double rows, six and twelve blades) using CFD. From the calculation results, the six-blade single row turbine shows the best performance, in which the highest power and torque coefficients reach up to about 34 % and 36 %, respectively, at TSR=0.94. However, despite of lower power coefficient, by adding more blades, the torque's extraction of twelve-blade turbine, especially the double row type, is less fluctuate than that of the six-blade setups.

A Study on Power Performance of a 1kW Class Vane Tidal Turbine

  • Yang, Changjo;Nguyen, Manh Hung;Hoang, Anh Dung
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.2
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    • pp.143-151
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    • 2015
  • Recently, tidal current energy conversion is a promising way to harness the power of tides in order to meet the growing demands of energy utilization. A new concept of tidal current energy conversion device, named Vane Tidal Turbine (VTT), is introduced in this study. VTT has several special features that are potentially more advantageous than the conventional tidal turbines, such as propeller type tidal turbines. The purpose of this study on VTT is to analyze the possibility of extracting the hydrokinetic energy of tidal current and converting it into electricity, and evaluate the performance of turbines for various numbers of blades (six, eight and twelve) using Computational Fluid Dynamics (CFD). At various tip-speed ratios (TSR), the six-bladed turbine obtains the highest power and torque coefficients, power efficiency is up to 28% at TSR = 1.89. Otherwise, the twelve blade design captures the smallest portion of available tidal current energy at all TSRs. However, by adding more blades, torque extracted from the rotor shaft of twelve-bladed turbine is more uniform due to the less interrupted generation of force for a period of time (one revolution).

Numerical simulations of a horizontal axis water turbine designed for underwater mooring platforms

  • Tian, Wenlong;Song, Baowei;VanZwieten, James H.;Pyakurel, Parakram;Li, Yanjun
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.8 no.1
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    • pp.73-82
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    • 2016
  • In order to extend the operational life of Underwater Moored Platforms (UMPs), a horizontal axis water turbine is designed to supply energy for the UMPs. The turbine, equipped with controllable blades, can be opened to generate power and charge the UMPs in moored state. Three-dimensional Computational Fluid Dynamics (CFD) simulations are performed to study the characteristics of power, thrust and the wake of the turbine. Particularly, the effect of the installation position of the turbine is considered. Simulations are based on the Reynolds Averaged Navier-Stokes (RANS) equations and the shear stress transport ${\kappa}-{\omega}$ turbulent model is utilized. The numerical method is validated using existing experimental data. The simulation results show that this turbine has a maximum power coefficient of 0.327 when the turbine is installed near the tail of the UMP. The flow structure near the blade and in the wake are also discussed.

EFFECTS ON ER,CR:YSGG LASER ON PERI-IMPLANTITIS (임프란트 주위염에 대한 Er,Cr:YSGG 레이저 조사가 미치는 영향)

  • Choi, Sung-Lim;Kim, Jin-Hwan;Hwang, Dong-Hyeon;Min, Seung-Ki
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.30 no.5
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    • pp.428-436
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    • 2008
  • For Longevity of implant, considerations of biomechanical and microbiological aspects must be done. Recently, due to the remarkable development of bone grafting procedure. Implant has been implanted into the more favorable sites but peri-implantitis resulted from periodontal bacteria may obscure the long-term prognosis. Although many different modalities have been introduced to treat the failed implant. Implant's surface and irreversible bony destruction around the implant prevents good result. After Er,Cr:YSGG (waterlase) laser using the wave-length of 2780nm has been introduced to dental field, good results have been reported. Because waterlase uses the hydrokinetic force of water. It is excellent device to detoxify the implant surface mechanically without the heat generation and damage to the implant surface. We designed to evaluate waterlase effect on the peri-implantitis has been occurred after implantation. Four beagle dogs were involved. We have made four premolar extraction in each right and left side of the lower jaw and placed two implants in the anterior of the jaw as a control and six implant were placed posterior in each socket after extraction immediately as an experimental group. We tied floss-silk in each implant to make peri-implantitis intentionally. After three months, we explored peri-implant sites on each experimental fixtures. Using waterlase laser irradiation was performed on that implantitis sites under 3W, air 30% and water 20% intensity for 2 minutes. In control group, we repositioned the flap to cover the exposed fixture without any supportive care. Three months later, we sacrificed experimental animals and extracted and preparated bone blocks with Donath and Breuner (982), Donath (988)'s methods and examined under microscope. We have obtained good re-osseointegration around fixtures after treating with waterlaser irradiation. But it was shown fibroosseointegration in the control group.

Numerical Study of Non-Newtonian Flow Characteristics in Sudden Contraction-Expansion Channel (급축소-확대관에서 비뉴턴유체의 유동 특성에 관한 수치적 연구)

  • Kim, Hyung Min
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.6
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    • pp.591-597
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    • 2013
  • Because most existing non-Newtonian models are not suitable for application to the lattice Boltzmann method, theoretical and numerical studies in this regard remain challenging. In this study, the hydrokinetic (HK) model was modified and applied to a 3D sudden contraction-expansion channel flow, and the characteristics of the HK model flow were evaluated to generate non-trivial predictions in three-dimensional strong shear flows. The HK model is very efficient for application to the lattice Boltzmann method because it utilizes the shear rate and relaxation time. However, the simulation would be unstable in a high shear flow field because the local relaxation time sharply decreases with an increase in the shear rate in a strong shear flow field. In the HK model, it may become necessary to truncate the relaxation time and non-dimensional parameter to obtain stable numerical results.

EFFECTS OF THE ER,CR:YSGG LASER ON BONE BED PREPARATION WITH VARIOUS LASER TIPS

  • Kim, Seong-Kyun;Heo, Seong-Joo;Koak, Jai-Young;Hong, Seong-Doo;Lee, Shin-Jae;Lee, Joo-Hee
    • The Journal of Korean Academy of Prosthodontics
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    • v.46 no.3
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    • pp.255-260
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    • 2008
  • STATEMENT OF PROBLEM: Preparation of implant beds with lasers is considered a safe and reliable method, but the accuracy of this technique has not been examined. PURPOSE: The purpose of this study was to evaluate the accuracy and effectiveness of implant bed preparation using an Er,Cr:YSGG laser. MATERIAL AND METHODS: An Er,Cr:YSGG laser was applied to pig rib bone. The laser was employed at a 5.75 W power setting, 30 Hz/sec pulse repetition, and 70 ${\mu}s$ pulse duration with 50 % water and 60% air spray. According to laser tips the groups were divided as follows; Group 1: paralleled - shaped sapphire tip (0.6 mm${\Phi}$), Group 2: paralleled - shaped zirconia tip (0.6 mm${\Phi}$), Group 3: tapered sapphire tip (0.4 mm${\Phi}$). The Er,Cr:YSGG laser tip was separated by 1 mm from the bone and applied for 15 seconds in a non-contact mode. After the application, the bone was sectioned for specimens. Histologic measurements were determined by computerized morphometry. The length of the prepared bone surface was measured and the width of the entrance was measured. The results were analyzed with one-way ANOVA (P<0.05). RESULTS: The prepared length of group 3 was longer than that of group 2. The prepared bone width was larger than the width of the laser tip in every group. Additional bone removal was observed adjacent to the prepared area and displayed an irregular surface. CONCLUSION & DISCUSSION: Different cutting effects were observed according to the laser tip, emphasizing the importance of proper tip selection in the clinical setting. This preliminary study supported the existence of hydrokinetic effects.