Wind turbines are getting larger, and the rotor diameter of 10 MW class wind turbine is nearly 200 meters. The difference of wind speed between the highest position and the lowest position in large rotor diameter will be large and the effect to power generation or effect to the fatigue by large fluctuation of wind load might be ignored. In offshore area, wind shear is not larger than onshore area, but that effect is also important. Authors developed a scale model of wind turbine which can be controlled 3 blade pitch angles individually and carried out model test in wind tunnel with modified wind shear. Firstly, wind speed distribution with honey comb board was measured and strong wind shear was modeled. Secondly characteristics of model turbine were measured in wind shear. Finally, individual blade pitch control was applied and its effect was observed.

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Control logic can be defined as the software platform which provides the basis of applying control demands to the wind turbine. This platform consists of filters, mathematical operators, software computations, signal processing, controllers and all other interactive programs needed to govern the wind turbine. Noticeably, this control logic can affect the behavior of the wind turbine. Specifically, for an offshore wind turbine in which negative damping may happen as a result of a weak controller design, the analysis of the control logic impacts on the machine is of high importance. The goal of this research is to study the behavior of the control logic on an offshore wind turbine.

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In this paper, the measured and calculated load of 7MW offshore wind turbine on V-shaped semi-submersible floating structure installed off the coast of Fukushima prefecture is presented. Simulation model is established taking account of literatures, in-house CFD and water tank test results. Numerical simulations have been carried out for both fatigue and extreme load and compared with the measurement results which have been obtained throughout the measurement campaign. From the comparisons, it is concluded that the analytical model and methodologies used for the evaluation are appropriate and suitable for the floating offshore wind turbine on V-shaped semi-submersible floating structure.

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To increase the competitiveness of offshore wind industry, cost-effective and time-efficient installation methods are needed. This work examines a novel installation concept using a catamaran vessel, which is specially designed to carry up to four tower-nacelle-rotor assemblies and perform offshore installation. The main challenge is to reduce the tower bottom motions induced by the vessel motions when it is placed on top of the foundation. A bottom fixed wind turbine foundation is considered in this study. An onboard gripper system is used to move the tower assembly along the vessel and perform the installation of turbine assembly onto turbine foundation. 1) Vessel is first positioned with its stern connected to the foundation through another gripper system, allowing only relative heave motions. 2) The turbine assembly is then transported to the vessel stern and it is hold right above the foundation. 3) Before the actual lowering and installation, the gripper and assembly are under active motion control so that they are kept steady in the vertical direction relative to the foundation top. 4) Once 3) is realized, the actual lowering and installation can start with active motion control on, to avoid unnecessary contact between assembly and foundation. The 3rd phase of the installation is numerically simulated. In the numerical simulation, an active force in vertical direction is added to control the assembly's vertical motion. The numerical simulation is performed using SIMO and RIFLEX under the SIMA environment.

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We have the responsibility to develop sustainable energy such as wind power for the benefit of future generations. The accident at the Fukushima nuclear power plant has made it clear that nuclear power is very difficult to control and alternatives to both nuclear power and fossil fuels are essential. The prime candidates are renewable energy sources such as solar power and wind power. Seventy percent of the earth’s total area is ocean, of which about 64% is deeper than 200 meters named offshore. Those deep sea areas have not been utilized until now due to some technical challenges. These expansive ocean areas could be a major energy resource in the future. If we can discover a better solution for offshore wind farms in the deep sea, we need not use nuclear energy. The author as developed some concepts and prototypes over the past 10 years. This paper shows the concept of offshore wind turbines with self-stable VAWT with flip-up mechanism and triangle combined floating structure with flexible rectangular link mechanism for deep sea locations.

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This paper reports some results of verification of advanced remote monitoring and maintenance methods for the future commercial operation of floating offshore windfarms. The authors have experienced verification of Operation and Maintenance (hereinafter called O&M) of the world’s largest 7MW floating offshore wind turbine off the coast of Fukushima. As well known, the biggest issue in O&M for such a large floating offshore wind turbine is the inefficiency of site works caused by the difficulty of access. The authors have verified O&M based on two policies, reducing work required access, and safe & efficient work in access opportunities.

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In order to widely promote the large-scale floating offshore wind farm among the private sector, it is the deciding factor how much economical installation method can be developed with regard to the installation cost which accounts for a large proportion in investment costs. In this paper a preliminary design of a shared pile anchor was made based on the result of dynamic mooring simulation and it was found that a simple empirical design formula of an optimum pile specification can be established against N-value, which is useful for preliminary estimation of the installation cost.

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In recent years, single-point mooring (SPM) concept is widely employed in several branches in the naval architecture and marine engineering field, such as FPSOs, offshore oil rigs, etc. In the present work, we perform some numerical studies on the DeepCwind semisubmersible wind turbine, using the state-of-the-art open-source tool Fatigue, Aerodynamics, Structures and Turbulence (FAST). Results show that the SPM layout affects the natural periods of the wind turbine in rotational modes, as well as the mooring stiffness in the diagonal rotational and crossing rotational-translational terms, especially with relation to the yaw mode. Comparisons of the Response Amplitude Operators (RAOs) elucidate that the presence of wind affects significantly the sway, roll and yaw motions of the SPM layout. Finally, the weathervane test shows that an asymmetry exists in the free-yaw motion response when the semisubmersible wind turbine is moored by an SPM system.

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The structural damping is an important parameter in the seismic resistant design of wind turbine. In this study, the effect of soil properties on modal damping is studied. Firstly, a sway-rocking model is built to simulate soil-structure interaction, and results show that sway-rocking model simulates second mode shape better than fixed-foundation model. Secondly, the method to evaluate second mode damping ratio is proposed, and results show that the higher value of second mode damping ratio comparing to the guidelines is caused by soil-structure interaction and modal damping is evaluated accurately by using sway-rocking model. Thirdly, the effect of soil properties on modal damping ratios is systematically studied, and results show that for gravity foundation supported wind turbine, first mode damping ratio is close to structural damping ratio while second mode damping ratio is dominated by soil properties. These findings in this study can help to improve design of gravity foundation supported wind turbine.

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Spar is one of the promising floating structures which supports wind turbine. In general, some lower part of spar is used as a ballast tank. It is possible to replace this part with non-watertight structure because this part has no statical contribution. A new spar with vertical damping plates was proposed. The authors made the models of this spar, a classic spar and a spar with heave plates (similar to truss spar), with the same stability. The motions were compared in regular waves. It was found that the spar with vertical plates is promising because pitching motion and nacelle acceleration reduced.

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We conduct subsonic wind-tunnel experiments, in order to investigate the basic aerodynamic characteristics of an autorotating finite flat plate in uniform mainstream, which has a potential for new windmills and waterwheels with very simple structures in addition to new mixers/diffusers. The present study focuses on both the effects of an aspect ratio AR and a tip-speed ratio Ω* upon the tumbling of the flat plate with a low thickness-to-depth ratio λ=0.013-0.02. We carry out the measurements using a torquemeter together with the synchronised measurements of the plate’s attack angle αfor the analyses with phase-averaging technique. As a result, the torque coefficient CT tends to decreases with increasing Ω*, and CT tends to become large with increasing AR. Power coefficient CP shows that the present phenomenon is suitable for low-speed windmills and waterwheels.

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Three dimension computational fluid dynamics was carried out to investigate the effects of horizontal arms on the performance of a straight-bladed vertical axis wind turbine. Three rotor models having different arms in terms of the cross section (airfoil, rectangular, circular), in addition to the armless rotor model, were calculated. Pressure-based total drag caused by the existence of arms became the greatest in the case of cylindrical arm, followed by the cases of rectangular arm and airfoil arm.

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The performances of the straight-bladed Darrieus wind turbine with fixed and variable-pitch mechanism were investigated by the open circuit-type wind tunnel test and the numerical analysis with ANSYS Fluent. The present research aims to investigate the effect of the position in a shear flow to wind turbine on the power. The offset coefficient Ψ(= Y/D), which is the ratio of the distance between the tip of the porous flat plate and the center of the rotor (y= 0) to the diameter of wind turbine, was varied from −0.25 to 0.375. It was found that the fixed and variable-pitch wind turbine shave optimum positions in a shear flow.

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In this report, the results of a wind test in order to investigate the influence of the interaction between the lift-type and the drag-type turbine blades on the performance of the vertical axis hybrid turbine is shown. As a result of power characteristics based on geometrical parameters such as the relative angle of the blade, the maximum values of the tip speed ratio and the power coefficient are improved according to the condition. In conclusion, we show the results of higher performance than the original lift-type turbine by considering the aerodynamic interaction and some geometrical parameters.

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Our study aims to improve the performance of cross-flow wind turbine by using two flow deflectors as wind collector that improve the ambient wind environment of the wind turbine. In this study, influence of upscaling of cross-flow wind turbine with two flow deflectors was investigated, namely three types of the wind turbine models were examined, one was the base model with 114 mm swept diameter and 12 blades and the other two were upscaled 1.5 times in swept diameter. Each upscaled model has different blade airfoil size and the number of blades. One upscaled model had similar figure to the base model and the other had 19 blades the airfoil size of which was same as that of base model. For these three types of wind turbine models with and without two flow deflectors, the experimental performance test and 2D numerical flow analysis were carried out and the influence of upscaling of cross-flow wind turbine with two flow deflectors were considered. As a result, with two flow deflectors, the upscaled wind turbine with smaller blade airfoil than flow deflectors showed higher performance than the other the blade airfoils of which have same size as flow deflectors.

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We are aiming to analyze Inverse tapered blade that produced by inverting the chord length at blade tip and blade root and Taper blade based on CLARK-Y airfoil; by running test in wind tunnel at 13 m/s wind speed. Simulate both of them with ANSYS Fluent software with different Reynold’s numbers relatively with different angle of attacks started with (-15) degrees and ended up with (20) degrees. Finally, using the simulation results in Q-blade software with the Blade Element Methods (BEM) to produce Cp - λ curves. The other aim is to understand the physics of the inversed tapered blade.

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We developed a wind concentrator for a cross flow wind turbine consisting of an arc-shaped wind-shield and a diffuser with a flange. By conducting wind tunnel experiments (WTE) and computational fluid dynamics (CFD) simulations, we investigated the effects of this wind concentrator on the performance of the cross-flow wind turbine. We found that with the flange height h became higher, the power coefficient increased from h/D = 0.3125 to h/D = 0.875 (D: diameter of the wind turbine). In addition, we found that with an increase in the semi-open angle φ, the power coefficient generally increased from φ = 0° to φ = 40°.

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This research aims at promoting renewable energy investment opportunities in Malaysia. Though there are positive attempts on Solar PV installations, due to its capital intensiveness, the progress is slow and lacks behind the annual targets. Hence, the government is planning to diversity electricity generations in other forms of renewable energy resources. However, the average wind velocity in Malaysia is 2 m/s, which is very low for energy production by commercial wind turbines. To give confidence to investors, this research work explores the wind profiles at several places in Malaysia and predicts the energy production of a few commercially available wind turbines.

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Orthopter-type wind turbine is a vertical axis wind turbine of which each blade rotates on their own axis meanwhile all of blades rotate on its main axis. The present paper describes the power coefficients of the orthopter-type wind turbine in uniform and shear flows. Three turbulence models, i.e. RNG k-ε, Realizable k-ε and SST k-ω, were investigated in 2-dimensional numerical simulation. The aim of this research is to identify the most reliable and effective turbulence model to simulate the performance of orthopter-type wind turbine. The result of the SST k-ω turbulence model has the closest value to the experimental data.

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In this study Thechno-Environmental feasibility analysis for prospective wind farms have been conducted for North part of Iran. A Multi Criteria Decision Making (MCDM) model has been built in ArcGIS software to obtain the most appropriate locations for wind turbines installation. In this step the most important and effective technical and environmental criteria have been applied on study area to eliminate the non-allowed areas for wind farms construction. Afterward, the obtained suitable areas have been classified based on International Electro-technical Commission (IEC) turbine classes using wind speed map at case study.

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This study investigates the performance of offshore wind simulation with the Weather Research and Forecasting model (WRF), using in-situ measurements from an onshore met mast and Galion scanning Lidars. A comparison with observations shows that the accuracy of WRF-simulated wind speed depends on the distance from coast and wind direction. It is also found that WRF underestimates a horizontal wind speed gradient in the shore-normal direction. This fact indicates that there is a risk that offshore wind resource can be underestimated, when it is estimated by using the WRF-simulated horizontal wind speed gradient together with the onshore met mast measurements.

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We installed the Galion Doppler wind profiler onshore Awaji Island to verify its performance, prior to the offshore wind assessment. The Galion scans horizontal wind speed and wind direction remotely and widely, meanwhile the MetMast measures the in-situ winds with conventional anemometers, and here we analyze their measurements for comparison. As a result, strong correlation was found between these two devices, indicating the Galion Lidar has robust accuracy.

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Distributed hydrodynamic forces on circular heave plates are investigated by Large Eddy Simulation (LES) with volume of fluid (VOF) method. The predicted added mass and drag coefficients for a whole heave plate is firstly validated by water tank tests. The distributions of hydrodynamic loads on the circular heave plates are then investigated. It is found that maximum dynamic pressure occurs at plate center and decreases monotonically towards the outer regions. Finally, formulas of the distributed added mass and drag coefficients in the radial direction are proposed based on the numerical simulations, and effects of aspect ratio and diameter ratio on the distributed added mass and drag coefficients are investigated.

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In Fukushima Demonstration Project, 2MW FOWT “Fukushima Mirai” has produced electricity for four years since November 2013 without major trouble. During the demonstration, field test data have been obtained and analyzed. In WT emergency shutdown test the floater was in free roll condition and decay of motion was recorded. The data was used to modify a numerical model. In this pater damping of floater motion is compared between water tank test and field test. Discussion on damping was given and the design based on the tank test is found to be in safe side.

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The authors have proposed a stress prediction formula for a grouted connection of an offshore wind turbine without shear keys by considering equilibrium between bending moment and shear force and showed its validation by the finite element analyses in a previously issued paper. In this paper, a scaled model test which models the grouted connection is discussed. It is shown that the proposed stress formula is consistent with the experimental results and that the failure.

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Fluid-Structure Interaction (FSI) is a critical problem in the wind turbine operations. Reliable FSI computations is a necessary crucial step towards achieving a safe efficient and prolonged operational lifetime for wind turbines. In this work, FSI computations in being held on the GE 1.5XLE wind turbine blade as a preliminary step in the developing of a reliable FSI model for wind turbine simulations. The fully resolved turbine blades are simulated in turbulent flow (k-ω SST model) with inlet velocity 12 m/s and turbine angular velocity of 2.22 rad/s. The aerodynamic loadings are firstly computed using Ansys FLUENT. The pressure and velocity distributions are then passed on to Ansys Mechanical to get the resultant structural deformations and stresses. The aeroelastic coupling effects from the CFD solver are then verified against the analytical solution showing a very good agreement.

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The performance of the wind turbine blade is made improved by using the performance of the two dimensional cross-section. The actual flow field around the blade is complicated by three-dimensional flow in which the flow in the blade span direction also exists. Therefore, as one of the better blade-design methods, the development of blades considering three-dimensional flow is necessary. However, the details of the flow field around the wind turbine blade under operation are still unknown. In this study, the flow field around a wind turbine in a wind tunnel is measured using Laser Doppler Velocimetry.

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The drag-type multi-blade vertical-axis wind turbine has high start-up torque and self-starts easily, but in many cases its efficiency is lower than that of a lift-type wind turbine. To increase the turbine output, we installed stationary vanes around the rotating blades. In this paper, we report the results of an experiment conducted at a wind tunnel facility to clarify the wind speed distribution from the stationary vanes to the rotating blades, which is necessary for estimating the wind turbine output from the lift-to-drag coefficient of the rotating blades.

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The paper describes control of wingtip vortices generated by vertical type Magnus wind turbine. The wind turbine consists of three circular cylinders. Each cylinder rotates on its own vertical axis and moves in orbit. Wingtip vortices cause decrease of power generation capacity and aerodynamic noise. Therefore, the study aims to control wingtip vortices. Numerical study was conducted for 14 models to find out control factors to suppress wingtip vortices. Consequently, two devices are found most effective. One is the protection plates placed at both end of the cylinder blades, and the other is curved wings placed along the cylinder blades.

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The study aims to improve the performance of a new horizontal type of wind turbine with a circular cylinder driven by longitudinal vortex. First, a simple model was numerically used to clarify the generation mechanism of longitudinal vortex. The necklace shaped vortex forms steadily behind the cylinder and contributes to generation of constant lift forces on the cylinder. Consequently, it was found that the gap between the cylinder and the plate plays a crucial role in inducing the vortex. The optimal gap was clarified by numerical simulation. Finally, enhancement of wind turbine performance was confirmed numerically and experimentally.

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For offshore wind resource assessment in nearshore waters with mesoscale model downscaling, it is important to evaluate the model-simulated horizontal wind speed gradient at a wind turbine hub height. This study investigates the accuracy of horizontal wind speed gradient simulated by the Weather Research and Forecasting model (WRF) using the observation from dual scanning lidar measurements on the coast of Kamisu in Japan. The accuracy validation shows that WRF underestimates horizontal wind speed gradient during the target period. In term of wind direction, the underestimation is more frequently found when wind blows from land sectors. It is moreover found that this underestimation cannot be improved by only changing the planetary boundary layer schemes in the WRF simulation.

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A new analytical wake model is proposed to predict the wake deflection, mean velocity, and turbulence intensity in the wake flow of yawed wind turbines. Firstly, two kinds of operating condition with different thrust coefficients under two types of inflow with different ambient turbulence intensity are simulated for two yaw angles by the Reynolds stress model. The wake deflection, mean velocity and turbulence intensity in the wakes are systematically investigated. A new wake deflection model is then proposed to analytically predict the wake center trajectory in the yawed condition. Finally, the proposed wake deflection model is incorporated in the Gaussian-based wake model. The wake deflection, velocity deficit and added turbulence intensity in the wake predicted by the proposed model show good agreement with the experimental data and numerical results.

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To capture the wake downstream over complex terrain, we installed a scanning LiDAR at a real windfarm turbine in a mountainous site. The LiDAR successfully captured the spatio-temporal structures of multiple wake events. A significant wind reduction was observed up to 1.5D (D=rotor diameter) downstream of the turbine. Around 2D–2.5D leeward, the wind gradually strengthened, indicating a recovery in wind speed.

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In order to promote the use of renewable energy in Japan, the author showed the census data on wind power of prefectures in Japan as the cartogram maps in a representation method. The census data includes the wind power potential, the current capacity of wind turbine, the electrical demand, and so on. The representation method with cartogram is able to express as the difference between prefectures and is also characterized as deformed map size and shape from those in normal map. This presentation method is effective for making “visualization”, “easy understanding”, and “implementation”.

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Together with LiDAR observation data at an onshore site, a CFD model and a Meso-scale model are used to estimate wind condition at an offshore site, approximately 2 km away from the onshore site. The LiDAR observation shows that the wind conditions in the study area are greatly affected by thermodynamic phenomenon such as land and sea breezes as well as by dynamical effects from neighboring onshore topography. It is found that since the CFD model cannot take into account such thermodynamical effects, it can have larger estimation errors than the Meso-scale model. A proper choice of the height the LiDAR data of which is used as input into CFD model seems to be a key to the success of the estimation.

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Metocean measurement at Fukushima test site was carried out and metocean characteristics were investigated. The effect of met mast tower on the measured wind speed can be mitigated by using the CFD simulation. Furthermore, the corrected wind speed data from the cup anemometer show good agreement with the wind speed measured by Lidar. The prevailing wind direction is NNW in winter and SSW in summer. The spectral significant wave height and period measured by wave buoy show good agreement with the statistical significant wave height and period measured by the wave meter. The prevailing wave direction is easterly all through the year. The current speed and direction measured by ADCP and wave meter show good agreement. The prevailing current direction is southbound cause by local current (Oya-shio)

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This study investigates the FEM analysis for a 750 kW wind turbine which suffered from bolt fatigue damages at the tower top flange. FEM analysis considering the complicated structure is required for precise stress evaluation. The simulation result shows good agreement with measured strain distribution. Modeling of bolts using beam elements are proposed to reduce calculation time, and the bolt tension force shows good agreement with bolts using solid elements. Consequently the nonlinear relation between the bolt pre-tension force and nominal force is evaluated. The analysis shows that the reduction of bolt tension resulted in the bolt fatigue failure.

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A wind shear estimation method based on the pitching moment, which acts to overturn a tower along a wind direction, measured at the top of the tower is proposed. We construct wind shear estimation models (WSEMs) using surrogate models whose input is a time-averaged pitching moment and various measurement data (e.g., wind speed). Using simulation data, we construct 20 WSEMs with various input combination and surrogate methods to select a model with the highest accuracy. Subsequently, the best WSEM is applied to a real turbine to validate its accuracy in real wind condition.

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This study aims to investigate the effectiveness of wind measurement and power performance of wind turbines using a nacelle-mounted LiDAR system. The effects of wind blockage by other wind turbines and yaw misalignments on wind measurements were investigated based on wind data measured by LiDAR. The results confirmed the influence of the yaw misalignments and verified that the blockage effect of a wind turbine affects the evaluation of its performance.

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New diagnosis method by comprehensive vibration analysis combined with latest machine learning technology is developed. In this method, overlapped signals are handled comprehensively as evaluation signals rather than noise. It can be applied to low-speed moving parts such as main rotor bearings of wind turbines, which are difficult to detect damage early, and as a result, the damage detection of wind turbine bearings is made possible three months before repair is required.

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To investigate the acoustic characteristics of aerodynamic noise produced by longitudinal vortex behind front-pillar of a vehicle, longitudinal vortex was reproduced by a delta wing whose attack angle of 15 degrees in the uniform flow velocity 30 m/s. Computational Fluid Dynamics (CFD) investigated the acoustic characteristics of longitudinal vortex in terms of rotational speed, vorticity and pressure fluctuations on the wing surface. As a result, it is considered that large acoustic pressure with high frequency may be generated at the tip and small one with low frequency at the rear, respectively.

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Longitudinal vortex is generated behind the front-pillar of automobiles. The vortex induces strong aerodynamic noise at high speed cruising. To investigate generation mechanism of aerodynamic noise, the vortex was reproduced by the delta wing whose attack angle of 15 degrees was merged in the uniform flow at 10, 20, 30m/s. Time derivative of wing surface pressure fluctuations regarded as aerodynamic noise source were measured in the low noise wind tunnel. Consequently, it was found that higher frequency of 3 kHz was largest close to the tip of the vortex, and the lower 500 Hz peaked at the rear.

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An aerodynamic brake which uses air resistance to suppress the rotational speed as the rotational speed increases is properly attached to the vertical axis of a gyro-mill type experimental wind turbine. It is revealed that this aerodynamic brake can widen the range of wind speeds under which the turbine can be safely operated. In this study, brake plates with different turning radii are attached to an experimental gyro-mill type wind turbine, the air resistance at each rotational speed is measured, and the adaptability to the wind turbine is evaluated

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The vertical axis wind turbine (VAWT) has support structures, which connect the blades and the rotating shaft of the wind turbine. The aerodynamic force acting on a VAWT is complicated and unexplained. Therefore, to clarify the aerodynamic force is important for designing a VAWT. This paper aimed at getting a better understanding of the aerodynamic force acting on VAWT.

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Small wind turbines often operate under highly turbulent conditions. A performance test and aero structural simulation was done on the power output of a 135W SWT in a turbulent environment. The results showed an increase in average power output with increasing turbulence intensity(TI), this was more pronounced at TI values above 25%. The increase in power was more pronounced at higher wind speeds (exceed 7m/s). A FAST model was used for simulation. There was good correlation between the FAST model and field test ,the error was never more than 20% for lower wind speeds and 8% for higher wind speeds.

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A novel wind turbine that can operate as both horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT) is under development. The wind turbine (D=750mm) utilizes the exhaust flow from a cooling tower in order to generate electricity. In this study, the power performances as both types were calculated by computational fluid dynamics (CFD). The effects of the shape of a nose cone on the performance were also investigated in the case of HAWT mode. A small brim at the edge of the nose cone did not give significant effects on the rotor power performance.

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The angle of attack of the blades and the Reynolds number of the Vertical Axis Wind Turbine (VAWT) vary greatly depending on the azimuth angle. Also, the flow passing through the downstream blade is complicated as it is disturbed by the blade passing through the upstream and the rotor shaft. Therefore, the load acting on the VAWT is much complicated and fluctuates largely during rotation. In this study, wind tunnel experiments were conducted to clarify the load acting on the VAWT.

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Characteristics of ribbon type wind turbine were investigated by wind tunnel experiments. In the ring with a flange at the rear end, the wind turbine power increased. This increase was remarkable when the flange diameter was large. The power coefficient due to the swept area based on the flange decreased as the flange became larger. With the large flange, wind speed reduction effect in the wake was observed in a wide range. Small flange gave lower wind speed around the turbine center. Tip speed ratio hardly affected the wind speed reduction effect.

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In this study, potential of wind power generation in the Hida-gawa riverside area is estimated by theoretical and numerical modellings with observational data. In-situ campaign observations indicate that the 10-min wind speed in the riverside area is approximately 1.5 times larger than that in the landside area. Theoretical estimation based on the conservation laws of mass, momentum and heat in a valley is in good agreement with the in-situ observations. Large eddy simulations on a slope with different roughness also can reproduce a strong wind jet above the riverside area with which is approximately 1.5 times larger than in the landside area. Rough estimations based on the knowledge obtained in this study suggests that the wind power generation potential by the riverside wind in the Hida-gawa River can achieve more than double that of the landside area.

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The inverse diffusion flame is formed in the combustor of a partial-combustion-type gas reformer for tar reduction in the producer gas formed by the gasification of the woody biomass. Pyrolysis and polymerization of tar occur simultaneously at the vicinity of the inverse diffusion flame. Soot forms during the polymerization of tar. In this study, to reveal the effect of changing the diluent of oxidizer on the formation of soot and polycyclic aromatic hydrocarbons (PAHs), laser induced incandescence (LII) and laser induced fluorescence (LIF) were at domain of laminar inverse diffusion flame. Results show that carbon dioxide addition to the oxidizer makes the flame sharp and soot and PAHs decreased.

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