The authors have invented a unique counter-rotating type tidal stream power unit composed of tandem propellers and a double rotational armature type peculiar generator without the traditional stator. The front and the rear propellers counter-drive the inner and the outer armatures of the peculiar generator, respectively. The unit has the fruitful advantages that not only the output is sufficiently higher, but also the rotational moment hardly act on the pillar because the rotational torque of both propellers/armatures are counter-balanced in the unit. This paper discusses experimentally the performances of the power unit and the effects of the propeller rotation on the force acting on the pillar. The axial force acting on the pillar increases with the increase of not only the stream velocity but also the drag of the tandem propellers.

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Pressure Retarded Osmosis (PRO) is one of the power generation systems. The flow in a membrane module is simulated for PRO operation with parameters, flow rate of sea water, permeability coefficient, hollow fiber diameter, module length, and module diameter. When we investigated the relationship about flow rate of sea water, module length and module diameter, it was found that there is best condition about these.

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Forward osmosis(FO) is recently paied attention to preprocessing of the Reverse Osmosis(RO). It can reduce the input power of RO plant. It is required to do lower the salt concentration at outlet and higher the permeation flow rate for the supply flow rate. The characteristics of the flow and osmosis are studied for the hollow fiber membrane module that used in RO system. It is cleared in the membrane module with experiments that permeation flow rate is increased and the salt concentration at outlet is decreased with the lower salt water flow rate. The salt concentration distribution in the module becomes uniform with higher salt water flow rate. We proposed the parameter for evaluation of the FO performance. By this parameter, the FO performance is high at the low salt water flow rate.

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Pressure Retarded Osmosis (PRO) is recently concerned to generate the power and to reduce the energy of RO system. The PRO power generation is based the osmotic pressure between the salt water and the fresh water that is about 7MPa. It is clear the condition to use the PRO in the RO system. The PRO power generation is closely relating to the permeation coefficient that is better over 0.6. The pressure ratio of the PRO and RO is recommended to 0.5. The concentration distribution is better to uniform in span direction. The uniform flow velocity is also need for the comfortable permeation.

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Recently, Solar energy attracts much attention as a clean energy resource due to the increasing environmental concerns of human being. CO2 is attractive as a working fluid instead of R134a, because GWP of CO2 is much less than of R134a. Solar CO2 Rankine System (SCRS) has been proposed by one of the authors, which can generate electrical and thermal energy by using solar energy as an energy resource and carbon dioxide as a working fluid. In order to optimize the SCRS, it is significantly important to investigate the performance of the turbine under the supercritical state of CO2. In the present study, the turbine was made by our laboratory taking into consideration the effect of the supercritical CO2. From the experimental results, it was found that the stable operation of the turbine was possible. And, the mass flow rate and the pressure difference between the inlet and outlet of the turbine affected to the performance.

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The air chamber characteristics of oscillating water column (OWC) type wave power generator are shown. Since an orifice is used in many cases as load of OWC instead of the air turbine from the ease of an experiment when estimating the air chamber characteristics by experiment, there are many examples of study for the OWC characteristics using the orifice load. However, when treating as a linear problem, investigation about a dumping coefficient is based and this paper shows the air chamber characteristics about a dumping coefficient. Moreover, although research of OWC characteristics about the compressibility effect of air is carried out by the past, the more detailed investigation is performed here in.

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Wells turbine has inherent disadvantages in comparison with conventional turbines: relative low efficiency at high flow coefficient and poor starting characteristics. To solve these problems, the authors propose Wells turbine with booster turbine for wave energy conversion. This turbine consists of three parts: a large Wells turbine, a small impulse turbine with fixed guide vanes for oscillating airflow, and a generator. It was conjectured that, by coupling the two axial flow turbines together, pneumatic energy from oscillating airflow is captured by Wells turbine at low flow coefficient and the impulse turbine gets the energy at high flow coefficient. As the first step of this study on the proposed turbine topology, the performance of turbines under steady flow conditions has been investigated experimentally by model testing. Furthermore, we estimated mean efficiency of the proposed turbine under oscillating flow conditions by quasi-steady analysis.

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In this study, the effect of 3-dimensional blade on the turbine characteristics has been investigated experimentally by model testing under steady flow conditions, in order to improve the stall characteristics of Wells turbine for wave energy conversion. The aim of 3-dimentional blade is to prevent flow separation on the suction surface near tip. the chord length is constant with radius and the blade profile changes gradually from hub to tip. The blade profiles are NACA0015 at hub, NACA0020 at mean radius and NACA0025 at tip. The performances of Wells turbine with 3-dimensional blades has been compared with those of original Wells turbine, i.e., the turbine with 2-dimensional blades. As a result, it was concluded that both the efficiency and stall characteristic of Wells turbine can be improved by the use of 3-dimensional blade.

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A straight-bladed vertical axis turbine for wave energy conversion has been proposed in order to develop a novel air turbine suitable for OWC based plant. Performances of the proposed turbine under steady flow conditions have been investigated experimentally by using a wind tunnel. The tested rotor has some straight blades with a profile of NACA4-diget series airfoil, a pitch diameter of 460 mm and a width of 490mm. The starting characteristics of the proposed turbine have been carried out by using quasi-steady analysis.

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This serial research intends propose a unique ocean wave power station, which is composed of the floating type platform with a pair of the floats lining up at the interval of one wavelength and the counter-rotating type wave power unit whose runners are submerged in the seawater at the middle position between floats. This paper discusses the relation between the oscillation and the turbine output. The runner may work in response to the head between the inner and the outer wave surfaces of the casing. This paper also discusses the effect of the station weight and the casing.

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A model test with a power take-off system composed of pulleys, belts and a generator is made and tank tests are carried out in regular waves to evaluate performance of a floating pendulum wave energy converter (FPWEC) proposed by Watabe. A primary conversion efficiency, secondary conversion efficiency and generating efficiency of this device are obtained from a free oscillation tests. Also, two dimensional numerical codes using a boundary element method based on velocity potential theory to estimate the primary conversion efficiency of this device is developed. The result of the code is validated by comparing with the experimental results.

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Wave energy is one of the most expected renewable energy resources. A floating point-absorber of wave energy is useful for the offshore powerful wave energy. In this paper, we studied the optimal control method for the wave energy converter in the waves. We employed the Approximate Complex-Conjugate Control (ACC) as the base control strategy, which has been studied in Europe. First, we developed the numerical simulator of the two-body heaving system by solving the movement equations with the Newmark-β methods. Second, we searched the optimal parameters which makes the efficiency of conversion largest by testing various values for regular waves. As a result, it was found that the optimal parameters depends on wave period.

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This paper proposes a fast and accurate model for analysis and performance improvement of the Archimedes screw turbine with permanent-magnet synchronous generator. It enables to simulate simplified flow-turbine-generator interactions using hydrostatics model of multiply-connected tank orifice. The model have been validated by experimental and calculated result of moving particle simulation. The design sensitivity analysis was carried out to optimize turbine shape and the result showed the best performance for 87% turbine efficiency and 48% totally efficiency is achievable at inclines of 5 degrees, 3-blades, 0.4 radius ratio, 1.5% clearance ratio and 3.0 gear ratio.

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Small hydropower generation is one of important alternative energy, and potential of small hydropower is great. Efficiency of small hydro turbines is lower than that of large one, and these small hydro turbine's common problems are out of operation by foreign materials. Then, there are demands for small hydro turbines to keep high performance and wide flow passage. Therefore, we adopted contra-rotating rotors which can be expected to achieve high performance and low-solidity rotors with wide flow passage in order to accomplish high performance and stable operation. These hydro turbines would be used in agricultural water channel. Performance of contra-rotating small hydro turbine is investigated when flow rate is changing because flow rate may be changing in the field. The test small hydro turbine has high tracking performance while flow rate changing and the performance of it is clarified by the experimental results

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Traditional type pumped storage system contributes to adjust the electric power unbalance between day and night, in general. The pump turbine unit is prepared for the power stabilization system, in this serial research, to provide the constant power with good quality for the grid system, even at the suddenly fluctuating/turbulent output from renewable energies. In the unit, the angular momentum change through the front impeller/runner must be the same as that through the rear impeller/runner, that is, the axial flow at the outlet for the axial flow at the inlet. Such flow conditions are advantageous to work at not only the pumping mode but also the turbine mode. This report discusses experimentally the performance of the unit, and verifies that this type unit is very effective to both operating modes.

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A Darrieus-type hydro-turbine system has been developed for hydropower utilization of extra-low head less than 2m. When the Darrieus-type hydro-turbine was installed in open channel, an increase of torque coefficient was observed with installing inlet nozzle. Especially, an installation of two-dimensional symmetric Straight Line Nozzle (SL Nozzle) with the converging angle of 45°produced larger torque than that of two-dimensional symmetric Half Diameter curved Nozzle (HD Nozzle). In the present study, in order to understand a cause of the difference of torque characteristic between SL Nozzle and HD Nozzle, two-dimensional numerical simulation is carried out. The relation between torque characteristics and the flow around rotating Darrieus blade is discussed.

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An undershot-type cross-flow water turbine does not require a casing for open channels and hence considerable simplification is attained. However, because this water turbine does not have a casing and has a free surface, it is believed that the internal flow considerably changes with the flow rate. We investigated the effect of flow rate on the performance of this water turbine with straight blades by an experiment and numerical analysis. As a result, the following facts became clear. When a flow rate is small, the power becomes small, but turbine efficiency becomes large. This is because the first-stage shock loss becomes small in a low rotational speed region and the second-stage shock loss becomes small in a high rotational speed region.

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This investigation is to grasp an accurate essence of open type hydraulic turbine for extremely low head hydropower utilization. Though the hydraulic turbine system, in general, might consist of casing and a draft tube for higher efficiency operation, it needs to cut the costs such as construction, running and maintenance for small hydro because low head utilization has small amount of energy. The author focus on open type hydraulic turbine, and then cross-flow type was adopted in this experiment. In this study, it was evaluated the relationship between the blade angle and the power performance. As a result, it was clarified that the optimum blade angle was changed comparing the conventional cross-flow turbine, consisting of casing and guide vane etc. For the open type, the CPmax=0.35 and 0.57 were obtained for undershot and waterfall type, respectively.

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Some foil sections of ducted cross flow water turbines were simulated by LES analysis. The equations are discretized by Finite volume method for space and Fractional step method for time. In this study, blade number is 16 and chord length is 15.5% of diameter. Important parameters are thickness and the edge shape of blade. The following are results of analysis. Best shape was outer-wedge type and round edge was not good in the standpoint of efficiency. Gap width between duct and blade increase the difference of efficiency by edge shape.

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As a small hydraulic power generation system utilizing an irrigation canal, the dockable two-dimensional oscillating wing system was developed. This system forms fish tail like wing movement with heaving and pitching motion. However, it also generates rotational fluctuation. In this paper, characteristics of rotation in the case of two-wing and three-wing setting. As the results, in the case of two wings, phase difference of 90 degree makes high rotation. In the case of three wings, phase difference of 120 degree by placing them evenly, achieve strongest and highest rotation. Maximum output of only 0.6W at U=0.5m/s, not enough power for electricity, was observed.

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Wind power as renewable energy has been come into the limelight by global warming and energy problems, and small type of wind turbine has been settled in general home and company. However, the widely used wind turbine is ordinary propeller type, and there is more complicated technique at the field of producing its propeller type of blade. From these circumstances, we have proposed a new type of wind turbine having the possibility of easy producing the wind turbine blade, maple seed blade concerning the rotation of falling maple seed in the nature world. At the previous study, we dealt with the maple seed wind turbine having 130 mm diameter of wind area to the turbine. In the present study, we dealt with the one having 1 m. We compared its power coefficient obtained from the wind turbine generator among installation conditions of the kind of blade shape and the settlement angle. It varies by the conditions, and there are the most suitable conditions. We also compared them to those at ordinary propeller type blade.

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Velocity distribution around straight-bladed vertical-axis wind turbine(VAWT) is measured by Laser Doppler Velocimetry. By the result of measurement, the spanwise distribution of circulation for the rotor blade is estimated. Estimated value of circulation of the VAWT shows highest near the center line, and reduces approaching the blade tip by the influence of tip vortex. In addition, the value circulation depends on the relative angle of attack and the relative wind speed near the center line. These results are useful to develop the method to predict the power of VAWT by correcting the power coefficient obtained from two-dimensional numerical analysis.

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Performance of a straight-bladed vertical axis wind turbine (VAWT) in skewed flow had been measured by changing the direction of the rotational axis relative to the direction of the main stream of a wind tunnel jet. The self-starting torque characteristics were deteriorated with increasing the inclination angle. Although maximum torque coefficient increased at wide range of inclination angle of -30 to 25 degrees, the variation as a function of the inclination angle was not symmetrical against the 0 degree. Increase in maximum power coefficient was observed between 0 and 20 degrees when inclining the rotational axis downstream.

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A wind-tunnel test was conducted to investigate wind fields behind an inclined flat panel on a floor, which corresponds to a photovoltaic panel on the ground. The tilt angle of the panel was 20°, which is typical value in real power stations and yields flow separations behind the panel. Two kinds of inflow turbulence were used: one has a disturbance where each of the active grid bars flaps in a random way to mimic the atmospheric turbulence (caseM) and the other has no additional disturbance, where all grid bars remain at rest (caseC). The comparison of cases C and M clearly shows that the inflow turbulence has serious effects on wind fluctuation behind a panel; the strong inflow turbulence activates wind fluctuation processes in the low-frequency regions.

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The common target for vehicles has always been lowest fuel consumption. This paper deals with a new cooling fan for vehicle engine. This fan is used as a wind turbine and generates electric power at high vehicle speed. Also this fan is used as a cooling fan at low speed or when the vehicle needs cooling. The fan can also reduce the vehicle air resistance along with the regeneration of the electric power. We have developed a fan rotor that can operate as cooling fan with the same performance as the current fan and can operate also as a wind turbine at higher performance than the current fan. The effectiveness of this proposal has been confirmed through the wind tunnel tests and CFD calculations.

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Wing-stroke type wind turbine generates electricity by stroking its blades, whose pitch angle changes periodically and passively, during stroke motion. With respect to the aerodynamic and mechanical characteristics of the wing-stoke turbine, there are many unsolved questions. A series of experiments on a small scale model have been conducted aiming to find operational condition which can obtain high efficiency of the turbine. Effects of pitch angle, stroke period and tip speed ratio of the blade on power and torque coefficients have been examined in this paper.

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The surface flow on rotor blade of Horizontal Axis Wind Turbine (HAWT) has complicated three-dimensional flow with span-wise velocity. Details of flow around rotor blades are not clarified sufficiently, since the measurement of velocity including boundary layer on rotor blades are difficult to reveal precisely. This paper's aim is to clarify the flow field around wind turbine blades. As the method, the measurement was performed on a model wind turbine having three blades by using of Laser Doppler Velocimeter (LDV)in wind tunnel. This paper showed effect that the parallel and radial velocity gives to the flow field around wind turbine blades by comparing some velocity profiles.

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In most cases the wind turbine development needs a wind tunnel which is required significant large expenditure. Computational Fluid Dynamics (CFD) is one of the tools to simulate the wind turbine characteristics. However, the three-dimensional analysis of CFD needs a long time to take the results. In this paper, the MEXICO rotor blades are calculated in two-dimension using Ansys Fluent. Then the performance of the wind turbine is predicted by the Blade Element Momentum (BEM) theory using the results of the lift and the drag coefficient calculated by the CFD. It is obtained that the power coefficient using BEM is very close to experimental data in the wind tunnel experiment.

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A wind turbine generator (WTG) with a power rating of 100kW and a variable pitch control system was developed for isolated islands and built on field test site, Kume-Island, Okinawa, in 2009. In field testing, several typhoons hit the Kume-Islands, however, the WTG didn't have serious damage. In this study, an analysis method of two-dimensional Computational Fluid Dynamics (CFD) is described and the computational results are compared with experimental data. Furthermore, WTG performance using the conventional Blade Element Momentum (BEM) theory is calculated and compared with field test results.

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This paper presents the optimization of the Chebyshev-Dyad linkage connected to a single blade wind turbine (NACA0012) in order to generate high torque. New type of wind turbine which swings in a unique trajectory path as figure eight is proposed. The numeric synthesis model is developed to optimize the different link parameters. The resultant of lift and drag forces developed in the wind blade is transferred to the rotating shaft by a link mechanism. These forces were assimilated in every node of the path to maximize the force to upgrade the characteristic performance. This slow type flap turbine is basically proposed in urban areas to install on top of the buildings as an alternative energy resource.

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The authors have developed the unique wind power unit which is composed of tandem wind rotors and a peculiar type generator with double rotational armatures. This paper discusses turbine performances of the unit with the optimized tandem wind rotors and the doubly fed induction generator, in the field test at the top of a building in Kyushu Institute of Technology. The characteristics of the output can be controlled by adjusting the input to the secondary circuit of the generator. That is, the input frequency must be adjusted in reverse proportion to relative rotational speed of the tandem wind rotor, to keep the induced frequency constant.

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The authors invented a superior wind power unit, which is composed of tandem wind rotors and a double rotational armature type generator without the conventional stator. The large-sized front wind rotor and the small-sized rear wind rotor drive respectively the inner and the outer armatures of the generator, in keeping the rotationl torque counter-balanced. In this paper discusses the performance of tandem wind rotors and the rotational behavior of tandem wind rotors. It was verified that the output is higher and is kept constant to keep in the rated operating made without the brake mechanisms.

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A coupled optimal aerodynamic design method of rotor and wind-lens for wind-lens turbine has been developed. In the present method, the aerodynamic design for the wind-lens turbine rotor is based on a two-dimensional blade element design and an axisymmetric viscous flow analysis. The shapes of rotor and wind-lens are optimized simultaneously by genetic algorithm. The present design method generated high performance wind-lens turbines. Three-dimensional Reynolds averaged Navier-Stokes (RANS) simulation shows that new wind-lens turbines designed by the present design method are superior to conventional one in the total performance.

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The wind turbines with a flanged-diffuser shroud -so called "wind-lens turbine"- are developed as one of high performance wind turbines by Ohya et al. In the paper, the wind turbine performances are presented for both steady and unsteady winds. As the results, the compact-type wind-lens turbine shows better performance than the only rotor one in sinusoidally oscillating velocity wind. In order to make clear the relationship between flow field and the turbine performance, the flow fields are investigated by PIV and CFD, so that the several important flow structures on the wind-lens turbine performances are found. In particular, it is newly realized that the blockage vortex periodically generates in downstream for the same wind oscillating frequency, and decreases the power coefficient. However, the blockage vortex is vanished from the time averaged results of PIV. Hence, the time series measurement and analysis are very important for the appropriate design of the wind turbine in the unsteady flow.

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In the World, renewable energy has been developing such as Solar power, geothermal energy, biomass energy and Wind energy. We are also conducting research on renewable energy such as wind energy in our laboratory. It has issued the results of many studies of the wind turbine with using the wind-lens technology developed in the field of wind energy in particular. We are now conducting Experiment of modeling Solar Tower Power Plant inside the laboratory, and Having obtained experimental results conducted diffuser type chimney , greatly increasing the amount of power generation. We will show you the remarkable outcome on the conference

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Noise and vibration control are the one of important issues. A sound insulation cover which covers a sound source is very useful for the noise reduction. The purpose of the present study is to investigate the acoustic characteristic of a sound insulation cover using acoustic/structure coupled analysis. It is clearly that sound pressure distributions inside and outside cover changed obviously according to the input frequency of a sound source. Several peaks of the sound pressure level were observed and these peaks were depended on the natural frequency and the resonance frequency of the insulation cover. Detail characteristic of the acoustic resonance phenomena was investigated and the mode of acoustic resonance changed by the sound source position.

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The complex flow features inside hard disk drive models are investigated experimentally in an axially symmetric shroud configurations. The experiment focuses on both pressure fluctuation and disk vibration. we observed pressure fluctuation excites the natural frequency of disk. The correlation of them in the turbulent flow between disks is evident.

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Wind tunnel experiments were conducted to study the aerodynamic characteristics of the spinning soccer balls with variously oriented spinning axes, of which balls are observed in a real game. Ball suspension apparatus with the piano wire strings and a shaft-bearing system through a soccer ball are studied with the cautions to obtain good linearity of spring support, non-interference to the other independent directions and the higher natural frequency of the system. The smooth rotation of a ball was accomplished with well spinning technique of dynamic balance. The 3-components aerodynamic forces of spinning ball in the fundamental arrangement of the axis are reported with the flight path calculations compared with ball flight observation.

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Wind tunnel experiments were conducted to study the aerodynamic characteristics of the spinning baseball ball with variously oriented spinning axes, of which balls are observed in a real game. Ball suspension apparatus with the piano wire strings and a shaft-bearing system through a ball are studied with the cautions to obtain good linearity spring support, non-interference to the other independent directions and the higher natural frequency of the system. The smooth rotation of a ball was accomplished with well tuning technique of dynamic balance. The 3-components aerodynamic forces in the 4-seam arrangements of the axis are reported with the variations of pitching and yawing angles. Ball trajectory calculations were also reported using these aerodynamic characteristics.

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In the present paper the attention is focused on the characteristics of aerodynamic sound radiated from two or three finned cylinders exposed to cross-flow. We measured the spectrum of SPL for the cylinder spacing ratios ranged from 0 to 1.05 in the transverse direction or the ratios from 0 to 6.8 in the flow direction at Reynolds number of 1.7 X 105. As a result, the peak SPL for two finned cylinders at the cylinder spacing ratios less than about 2.0 in the flow direction was smallest in the tandem finned cylinders. And the peak SPL was largest at the cylinder spacing ratio of 0.72 in the transverse direction. The peak SPL at the cylinder spacing ratios of 0.72 in the transverse direction and 1.24 in the flow direction for three finned cylinders was smaller than those of the two finned cylinders.

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We pay our attention to an aerodynamics sound in this study and study it. An effective thing was suggested, but after checking the reduction effect with the cylinder with the tape as other technique, an aerodynamics sound was reduced than the result that paid its attention to the surface state of the combination slant cylinder by aerodynamics sound reduction. Furthermore, we performed the investigation about the cause that an aerodynamics sound was reduced by inspecting data of C.O.P about the race. As a result, the disorder that was a noise source of the race understood that it was dispersed by attaching tape.

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This paper deals with the aerodynamic noise generated by a jet flow diffusion device. A gas turbine's flow velocity in a duct of the exhaust gas is about 50 meters per second. When an exhaust gas blows off inside a silencer, a loud noise is generated by the turbulent gas flow. The jet flow diffusion device is attached at the tip of circular duct and it is composed of side slits and a flow separate corn. In the experiments, the aerodynamic noises generated by the diffusion devices are measured. The effects of shape difference on the noise are estimated. As the results, the aerodynamic noise varies depending on the corn position, thickness of the wall of the device. And it is found that the noise tends to increase as the large flow diffusion effect.

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This paper deals with the aerodynamic sound generated by the perforated metal. Perforated metal is produced by stamp out the sheet metal using a press die. In this study, the perforated metal is attached at the tip of circular nozzle and it experiments by wind velocity 50 m/s. Aerodynamic sound measurement experiments show that the characteristics of the generated aerodynamic sound depend on the perforated metal thickness, hole diameter and its attachment orientation. Moreover, the measurement of velocity fluctuation of air flow flowing out from perforated metal is carried out. The result shows the perforated metal is effectivity for reduce the low frequency noise. The distribution of band overall of velocity fluctuation indicates the mechanism of reducing the low frequency noise generate from the jet.

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The aim of this investigation is to clarify effects of aerodynamic noise control with the dielectric barrier discharge (DBD) plasma actuator (PA) over the cascade of flat plates. The sound and velocity fields of flow around the cascade were measured with a low noise wind tunnel. The experiments were carried out at flow velocity from 5 m/s to 20 m/s by the expanded model of a front grille of automobile for basic research. The results showed aerodynamic noise from the cascade can be controlled with PA. The effect of noise reduction depended on the applied voltage and frequency of PAs. Moreover, the peak frequency becomes lower when the PAs were driven. As a result, the phase-lock of the shedding of the vortices from neighboring plates was weakened, and the acoustic resonance therefore did not occur. It indicated that the PAs are useful devices to control of aerodynamic noise.

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The objective of this study is to clarify the relationship between the tip vortex and aerodynamic noise of an open type propeller fan operating at vicinity of the maximum efficiency point. The influence of the internal flow on the aerodynamic noise is discussed with taking account of the axial direction relative position. In this experiment, when the relative position is 20 mm, the periodical noise at 200 Hz which is the low frequency side than of the blade passing frequency became large. The periodical noise became the one of the important factors for increasing the fan noise by 5dB. The periodical noise was generated by the interaction between the tip vortex and the partition of the fan. It was clarified that when the wake formed the flow regime of the high specific speed type impeller the blade tip vortex noise was generated.

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Centrifugal Turbo-Blower is able to produce high pressure, but operation sound of it is bigger than that of other blowers. The mechanism of the noise generation has to be elucidated in order to decrease that noise. In this study, we focus on lap area (gap between inlet pipe and impeller) which affects blower noise, and investigate the noise at lap area by measurement of sound level and numerical analysis. As a result, we found that there is a re-entrant flow from casing to impeller at lap area, and the interaction between the re-entrant flow and a suction flow causes the noise.

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Recently, it has been a problem of aerodynamic noise radiated from wind turbine blades, and noise prediction of the wind turbine is important. Then, airfoil noise under the various inflow conditions is measured by using the active turbulence generators (ATGs) in this study. The ATGs have 3 size of rotating plates with changing various swing angles in order to be varied independently turbulence intensity and eddy scale. And, we manufacture active turbulence generators (ATGs) which are 16 axis types to improve the non-uniformity of wind velocity with ATGs. In this paper, it is reported that the turbulence intensity and the eddy scale of inflow can be changed at 7% to 20% and at 18% to 30%, respectively. Also, it is cleared that sound pressure level of airfoil noise are increased by 5 to 15 dB in broadband frequency range of 100 to 5000 Hz in case of increase of turbulence intensity, and that the sound pressure level are increased by 5 to 15 dB in the range of 100 to 300 Hz in case of increase of eddy scale. And non-uniformity of wind velocity with the ATGs which are 16 axis types is 7%.

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The present paper shows the ability of Lattice Boltzmann method (LBM) to simulate flow and acoustic fields with low Mach number. Toward engineering applications which have complicated geometries and large computational domains, the computational method based on LBM using a Cartesian mesh was developed by the multi-scale model, the Building-cube method and a simple immersed boundary scheme. Furthermore, a low-pass filtering operator was used to suppress numerical instabilities caused by the use of low-resolution meshes. First, tonal noise generated from an airfoil in uniform flow was calculated by the isothermal model and the thermal model. The tone frequency and SPL of isothermal model show small differences from those of the thermal model. Secondary, broadband noise generated from a transitional boundary layer over an airfoil was simulated using the isothermal model. The computed frequency spectra of far-field sound agreed well with that of experimental data available in the literature.

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In this paper, three components of flow velocity around NACA0012 airfoil in some two dimensional sections are measured by using the stereo PIV method in order to clarify three dimensional vertical structures and unsteady behavior of airfoil tip flows. The Reynolds number based on the chord length of the airfoil and uniform flow velocity is 1.33X105, and the airfoil is under the high lift condition. The results shows primary vortex on the suction surface and secondary vortex on the airfoil tip are high fluctuated.

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The authors had invented a unique wind power unit composed of a large-sized front wind rotor, a small-sized rear wind rotor and a peculiar generator with inner and outer rotational armatures without the traditional stator. In the previous report, the relationship between the acoustic noise and flow conditions around the tandem wind rotor are discussed. Continuously, this paper discusses the effects of the blade profiles on the acoustic noise from tandem wind rotors. The chord of the rear blade should be decreases to reduce the acoustic noise in the tandem propellers.

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