Pursuit of Aerodynamics
Development of a wing form and blade configuration with high power generation efficiency
The WINPRO vertical type blades are suited to the winds of Japan where we experience winds from all points of the compass, because there is no necessity to change the orientation according to changes in the wind conditions.
With a wing form developed through a thorough pursuit of aerodynamic characteristics and optimized blade configuration, greater rotation force is generated compared with the former system not only under high speed wind conditions but also in the more frequent light winds.
WINPRO has developed a “Blade output forecast system” based on original blade element theory. We added theory validation through experimental and Computational Fluid Dynamics (CFD) analysis and have built up an output forecast system with the highest level of calculation accuracy in the industry.
Intensive simulations were carried out repeatedly for each WINPRO turbine product category using this output forecast system, and we have achieved wing form and blade configurations that realize high power generation under a variety of wind conditions.
Optimized design of wing form (lift and drag)
We have optimized the design based on the results of experiments on lift and drag and CFD validation using various wind speeds.
Figs.1 ~ 3 show calculation examples of lift/drag based on CFD, to validate flow velocity distribution, pressure distribution, flow separation and occurrence of swirl.
Fig.1 Flow velocity distribution
Fig.2 Pressure distribution
Fig.3 Relationship between angle of attack and flow velocity distribution
Fig.4 shows the calculation results for lift (CL) according to the wind direction at various angles and in this example the wind direction changes 360°.
Fig.4 Relationship between rotation angle and lift
Construction of vertical axis blade configuration
In order to maximize the power generation efficiency under various wind conditions, we have carried out a variety of research on the conversion efficiency of wind energy into electrical energy, start-up characteristics under light wind and blade output at each wind speed, using WINPRO’s original “output forecast system” developed based on know-how we have accumulated over the years and an enormous amount of data.
Concretely speaking, we input the characteristics of each wing form, blade configuration and wind speed into the “blade output forecast system” and calculate blade output according to the rotation speed shown in Fig.5.
Fig.6 shows an example of the calculation of blade output at each wind speed.
Fig.6 Output calculation at each wind speed
Validation of blade output
We validate the results of calculations using the forecast system by carrying out wind tunnel experiments and CFD analysis. Fig.7 shows the pressure distribution and flow velocity distribution calculated using CFD, and calculated effect between each blade is fed back to the blade output forecast system in order to increase the forecast accuracy and to incorporate the results in the optimized design of the blade configuration.
Fig.7 Pressure distribution and flow velocity distribution
Pursuit of Safety
Guaranteeing the life-endurance to withstand a max. average wind speed of 42.5m/s and maximum instantaneous wind speed of 60m/s by ensuring strength and fatigue design
Variable load including centrifugal force according to wind pressure and rotation speed and lift generated from the blade is constantly applied to the vertical axis blade and the arm that supports the blade, so we carry out detailed simulations repeatedly and design with sufficient strength to endure all resultant forces under all types of conditions.
Fig.8 shows an example of an S-N curve line for aluminum, and it is designed so that the stress amplitude applied to each part of the blade or arm due to variable load never exceeds the fatigue limit.
Fig.8 S/N curve line
Fig.9～Fig.11 show an example of the calculation results for displacement or stress.
Fig.9 Deformation amount distribution map for the blade
Fig.10 Stress distribution map for the blade
Fig.11 Arm stress distribution map
Auto variable electronic load control system
Wind speed changes instantaneously. Therefore, electricity is drawn out at low level so that rotation does not lose speed due to drawing out too much electricity.In order to enable the optimal amount of electricity to be drawn out at all times and to improve power generation efficiency further, we have developed an auto variable electronic load control system that uses feed-back control with the increase amount/decrease amount as correction factors.
Pursuit of Environmental Performance
Effective usage of sloping land
WINPRO wind power generators can be set on sloping land such as roadside slopes and riverbanks using our original technology. Concrete foundations have been used as the construction method for foundation work in the past, however, we have changed this to a method where the main body of the wind power generator is reinforced and fixed with a ground anchor, wind pressure receiving plate and guy wires. We are demonstrating and experimenting with simple and environmentally friendly construction methods.
Advantages of installing on a slope
● Possible to install on sloping land that would otherwise be lost space
● Foundation work can be simplified, construction time can be shortened and construction cost can be reduced because there is no need for land reclamation or earthworks.
The rotation speed of a vertical axis blade when generating electricity is low. Though the noise level in a residential area (daytime) is 40 ~ 50dB, when a wind power generator is operating (at RUN), the noise level is more than 10dB below this.
The noise from a hybrid street light is at a barely audible level, which is the same as whispering or the rustling of leaves. The noise from the blades of a wind turbine rotating in the wind is very small, so this is an extremely quiet power generator. The noise when the brake is used is almost the same level as when in normal operation.
Lightning strike countermeasures
WINPRO wind power generators are made of metals such as aluminum alloy and iron steel, so there is no risk of breakage or fire due to a lightning strike.
Bird strike countermeasures
The blades of a vertical axis type wind power generator present only a very small hazard zone to flying wildlife, so there should be no accidents due to bird strikes, etc.