The Study of Wake and Array of Double Wind Turbine

2013 ◽  
Vol 448-453 ◽  
pp. 1707-1711
Author(s):  
Rui Yang ◽  
Wei Wei Xia ◽  
Jin Long Li
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Turbulence Intensity ◽  
Fatigue Load ◽  
Wake Effect ◽  
Wake Field ◽  
Aerodynamic Interaction ◽  
Simulation Results ◽  
Effective Use ◽  
Wind Resources

For the effective use of wind resources, and in order to decrease the wake effect on the performance of wind turbine, a numerical simulation has carried out to the aerodynamic interaction between two rotors coaxial arrangement. At last the numerical simulation results are verified by experiment. The results show that downstream turbine makes the upstream diverging wake to be converged when coaxial arrangement, and the output of downstream turbine is affected by upstream wake when the distance is less than 5D.The wake field become more diffused after pass the downstream turbine, the area of diverging wake become larger than the wake of upstream turbine mainly due to the increase of turbulence intensity. The greater fatigue load will impact on the downstream turbine. At last the simulation results are in well agreement with the experimental results.

Dynamic Responses of the State-of-the-Art Floating System Integrating a Wind Turbine With a Steel Fish Farming Cage: Model Tests vs. Numerical Simulations

2021 ◽  
Author(s):  
Yu Lei ◽  
Xiang Yuan Zheng ◽  
Hua-dong Zheng
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Wind Turbine ◽  
Fish Farming ◽  
Dynamic Responses ◽  
Drag Coefficients ◽  
Free Decay ◽  
Floating System ◽  
Simulation Results ◽  
Decay Tests

Abstract This work is dedicated to comparing the experimental and numerical results of the dynamic responses of a novel floating system integrating a floating offshore wind turbine with a steel fish farming cage (FOWT-SFFC) under wind and wave loadings. The patents of this floating system have been successfully licensed recently in China and USA. The experimental study is carried out in the Ocean Basin of Tsinghua Shenzhen International Graduate School, with a Froude scaling of 1:30. A small commercial wind turbine is used to produce the scaled wind loads on FOWT-SFFC in terms of the similarity of thrust force. In this paper, the setup of model tests is described first. Second, a numerical model of prototype FOWT-SFFC is built in the software OrcaFlex. Then, this numerical model is calibrated and updated by the results of free decay tests and static offset tests in the basin. The numerical model also adopts three sets of drag coefficients. Finally, the experimental results of FOWT-SFFC under a variety of load cases are presented and compared with the numerical simulation results. They include seakeeping tests for hydrodynamic motion response amplitude operators (RAOs) and dynamic responses corresponding to normal operating and survival conditions. The numerical simulation results show that, though they are in good agreement with model test data especially on time records of dynamic responses, they are sensitive to the selection of drag coefficients particularly on extreme values and low-frequency spectral contents. Appropriate drag coefficients are suggested to be used in the numerical model for a specific environmental condition. Drag coefficients benchmarked from the free decay tests may not be suitable for moderate and harsh wave conditions.

Research the Influencing Factors of the Low Wind Speed Wind Turbine Fatigue Loads

2014 ◽  
Vol 1008-1009 ◽  
pp. 164-168
Author(s):  
Fa Ming Wu ◽  
Lei Wang ◽  
Dian Wang ◽  
Jia Bao Jing
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbulence Intensity ◽  
Fatigue Load ◽  
Annual Average ◽  
Average Wind Speed ◽  
Low Wind Speed ◽  
Air Density ◽  
Average Wind ◽  
Fatigue Loads

This paper analyzes three main factors (turbulence intensity, air density, annual average wind speed ) that influence the low wind speed wind turbine fatigue loads, In order to analyze the influence of each main parameters how to affect the fatigue load of low wind speed wind turbine, using a 2000kW wind turbine as an example on the simulation test , 3 turbulence, 4 air density and 7 annual average wind speed were employed. The results show that, with the air density, turbulence intensity and the annual average wind speed increases, the wind turbine of fatigue load increase in rule approximately. Based on the above rule, it can reduce fatigue loads and prolong the life of wind turbine in design optimization of low wind speed wind turbine and sit choice.

scholarly journals Wake Effect and Power Production of Wind Turbine Arrays

2015 ◽  
Vol 9 (11) ◽  
pp. 77
Author(s):  
Ismail Ismail ◽  
Samsul Kamal ◽  
Purnomo Purnomo ◽  
Sarjiya Sarjiya ◽  
Sulaiman Tampubolon
Keyword(s):  
Wind Turbine ◽  
Turbulence Intensity ◽  
Wake Flow ◽  
Mechanical Power ◽  
Centerline Velocity ◽  
Downwind Distance ◽  
Wake Effect ◽  
Velocity Deficit ◽  
Ambient Turbulence ◽  
Turbine Arrays

This study experimentally investigated the influence of wake effect and production of mechanical power in wind tunnel of wind turbine arrays. Wind turbine arrays consist of 2 rows with 3 columns for spacing wind turbines in rows apart in the windward direction 1.77 rotor diameters and apart in the crosswind direction 8.85 rotor diameters. The wake characteristics such as profiles of time averaged velocity, turbulence intensity, centerline velocity deficit and wake radius for far wake regions in position 1, 2, and 3 were measured and analysed. The vertical and lateral profiles of velocity and turbulence intensity were studied. Concerning the results from measured data, empirical relations for the centerline velocity deficit, turbulence intensity and wake radius were proposed. Based on the experimental results, the power loss is due to the wake flow of upwind turbine approximately 20% when the downwind distance 8.85 rotor diameters. This is different with numerical result study that 11% at downwind distance is 8.85 rotor diameters. This difference results from the influence of ambient turbulence on the production of mechanical power of the wind turbine.

Numerical Simulation and Wind Tunnel Studies of the Wind Load on Wind Turbine Structures

2011 ◽  
Vol 250-253 ◽  
pp. 3811-3814
Author(s):  
Cheng Hsin Chang ◽  
Jen Mu Wang ◽  
Chii Ming Cheng
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Tunnel Test ◽  
Bending Moment ◽  
Dynamic Mesh ◽  
Base Shear ◽  
Structural Responses ◽  
Simulation Results ◽  
Rng Turbulence Model

This paper investigated the structural responses of the wind turbine due to wind loads by performing the wind tunnel test and the Computational Fluid Dynamics, (CFD). The base shear force and the base moment of the wind turbine measured by the wind tunnel test were compared with the numerical simulation results. Both the numerical dynamic mesh and sliding mesh models were selected for the numerical simulations. The results showed that the dynamic mesh model was better than the sliding model by comparing to the wind tunnel test result. In the case of the k-epsilon RNG turbulence model, the prediction of the bending moment affecting by acrossswind was more than 50%, and the prediction of the force affecting by acrosswind was less than 3%. The both simulation results of the prototype and the full scale wind turbine were obtained by CFD model. The comparisons of the result showed that the error of Fxwas about 15% and Mywas about 13.5%.

scholarly journals Monin-Obukhov Similarity Theory for Modeling of Wind Turbine Wakes under Atmospheric Stable Conditions: Breakdown and Modifications

2019 ◽  
Author(s):  
Xing Xing Han ◽  
De You Liu ◽  
Chang Xu ◽  
Wen Zhong Shen ◽  
Lin Min Li ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbulence Intensity ◽  
Wind Shear ◽  
Similarity Theory ◽  
Turbulence Models ◽  
Wake Effect ◽  
Similarity Functions ◽  
Stable Conditions ◽  
Flow Similarity ◽  
Ambient Turbulence

Monin-Obukhov similarity theory (MOST) overestimates wind shear in some atmospheric stable conditions, i.e. Richardson number $R_f<0.25$. The overestimated wind shear that leads to an under-predicted friction wind speed and a lower ambient turbulence intensity for a given hub-height reference wind speed and a given roughness length, could influence wake modeling of a wind turbine. This work investigates the side effects of the breakdown of MOST on wake modeling under stable conditions and makes some modifications to the flow similarity functions to eliminate these side effects. Based on a field measurement in a wind farm, we firstly show that MOST predicts a larger wind shear for the atmospheric stability parameter $\zeta>0.1$ and proposes new flow similarity functions without constraining $R_f$ to limit the overestimated wind shear by MOST. Next, different turbulence models based on MOST and a modified one based on the new similarity functions are investigated through numerical simulations. These turbulence models are combined with the actuator disk model (AD) and Reynolds-averaged Navier–Stokes equations (RANS) to model wind turbine wakes under stable conditions. As compared to measurements, numerical results show that turbulence models based on MOST result in larger wake deficits and slower wake recovery rate with a square root of the mean-squared-error (RSME) of wake deficit in the range of 0.07-0.18. This overestimated wake effect is improved by applying the new similarity functions and the RSME of wake deficit is averagely reduced by 0.05. Finally, we check the role of the under-predicted turbulence intensity playing in the larger wake deficit predicted by models based MOST. Additional numerical simulations using the modified turbulence model are carried out, in which the roughness length is reduced to impose a hub-height ambient turbulence intensity equivalent to the MOST case. Simulation results show that reducing turbulence intensity enhances wake effects, however, it cannot reproduce the large wake deficit predicted by models based on MOST, which suggests that the overestimated wake effect by MOST could be also related to the overestimated wind shear.

scholarly journals Demonstration Experiment and Numerical Simulation Analysis of Full-Scale Barge-Type Floating Offshore Wind Turbine

2020 ◽  
Vol 8 (11) ◽  
pp. 880
Author(s):  
Ko Matias Adrian Kosasih ◽  
Hideyuki Suzuki ◽  
Hideyuki Niizato ◽  
Shigeki Okubo
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Measurement Data ◽  
Offshore Wind ◽  
Extreme Condition ◽  
Offshore Wind Turbine ◽  
Complex Flow ◽  
Development Organization ◽  
Floating Offshore Wind Turbines ◽  
Simulation Results

The development of Floating Offshore Wind Turbines (FOWT) has been progressing steadily. To utilize the moderate water depth of 50–100 m ocean space around Japan, a barge-type FOWT was installed in Kitakyushu as part of a demonstration project conducted by the New Energy and Industrial Technology Development Organization (NEDO) of Japan. The FOWT mounts a 3 MW two-bladed wind turbine with blade diameter of 100 m and hub height of 72 m. The barge-type floating support structure is equipped with a moonpool in the center and a skirt at its bottom and is moored with 9 lines of catenary chains. To investigate the dynamic behavior of the barge-type FOWT in extreme condition and the validity of the numerical simulation in modeling the effect of the complex flow around the floating structure to the FOWT’s motion response, the FOWT’s motion data during typhoon Tapah on 23 September 2019 were measured and compared with the simulation results. As the results, the simulation results showed a good agreement in general to the measurement data. However, some shifts in the peak frequency of the simulation’s motion spectrum and a disagreement in waves with shorter wave periods were also observed. The possible causes of these differences are discussed thoroughly in this paper.

Research of the Analysis Method on the Three Basics of the Wind Turbine Fatigue Loads

2014 ◽  
Vol 953-954 ◽  
pp. 432-436
Author(s):  
Lei Wang ◽  
Fa Ming Wu ◽  
Dian Wang
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbulence Intensity ◽  
Analysis Method ◽  
It Use ◽  
Air Density ◽  
Loads Analysis ◽  
Fatigue Loads ◽  
Wind Resources

The research has identified turbulence intensity, annual wind speed and air density as the three basics of fatigue loads, in this paper, we call it three basics for short. This paper presents a method to analyze the three basics of the wind turbine fatigue loads. It explains the fatigue loads analysis idea and method of the three basics and it use the analysis method to research the extent of the influence by using a 1650kW wind turbine as an example. It can be seen from the results that the wind resources increase one classification, the influence of the turbulence intensity is the greatest, then the annual wind speed, finally the air density.

Avalanche Features in Silicon Schottky-FETs in Accordance with Numerical Simulation Results

2006 ◽  
Vol 65 (16) ◽  
pp. 1533-1546
Author(s):  
Yu. Ye. Gordienko ◽  
S. A. Zuev ◽  
V. V. Starostenko ◽  
V. Yu. Tereshchenko ◽  
A. A. Shadrin
Keyword(s):  
Numerical Simulation ◽  
Simulation Results

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

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