Wind-lens technology Application to wind/water turbines and beyond Tomoyuki Nagai , Ph.D. on behalf of wind engineering section at RIAM, Kyushu University WREC 2015, June @ Bucharest Wind-lens turbine team members Professor Associate Professor Research Fellow Joint Researcher Joint Researcher Technical staff Technical staff Y. Ohya (project leader, RIAM director) T. Uchida T. Nagai K. Hayashida (Riamwind Corp.) H. Nishimura (Riamwind Corp.) K. Watanabe K. Sugitani Associate Professor T. Karasudani Professor S. Yoshida Associate Professor W. Wang Professor C. Hu Assistant Professor M. Sueyoshi Professor Y. Kyozuka Ph.D. Student And many more U. Goeltenbott Wind speed and wind energy Wind Power P , Wind Speed V V P∝V3 The output of a wind turbine is proportional to the incoming wind speed cubed. Therefore, a slight increase of the wind speed at the turbine rotor results in a dramatic increase of the turbine power output. Then, how can we accelerate the wind speed? Nozzle or Diffuser? - cont. Flow We “re” discovered that diffuser type shroud accelerates the incoming wind. But, the size needs to be reduced for practical application to wind turbines. “Nozzle” Additional “Brim” at the peripheral part of the exit “Diffuser” Diffuser Nozzle Wind speed distribution Wind-lens turbine Wind flow Brim Low-pressure region due to strong vortices Wind flows into this region Turbin e Diffuser shroud (Wind lens) Active utilization of shedding and vortex formation Quite unique way of designing an aerodynamic machine! “Wind lens” = Brimmed diffuser shroud Vortex shedding creates low pressure regions Two-dimensional DNS animation Diffuser shape For the practical installation of the Wind-lens diffusers to larger turbines, we have investigated more compact diffuser shapes Our dilemma is: Compact diffuser Current model Early prototype The prototype Circular type = less power enhancement…. Linear type Cycloid type 3kW prototype field test Cp*=0.54 based on the lens diameter (Rated Wind Speed 10m/s, Rotor dia. of 2.5m) 3,500 W Field Data (1min. average) 3,000 Cw=1.0 (Wind-lens Turbine) 2,500 2.5 times Increase Cw=0.4 (Conventional Wind Turbine) 2,000 1,500 1,000 500 Conventional Wind Turbine 0 0.0 2.0 4.0 6.0 The prototype 3kW WL turbine 8.0 10.0 12.0 m/s Cancelation of tip vortices Blue – Tip vortex Red – Induced vortex Diffuser surface Tip vortex and induced vortex interfere and cancel each other as they propagate downstream Reduction of tip vortex noise! A simulation result by DNS Current Wind-lens turbine models 3kW Wind-lens turbine Rotor D: 2.5m Diffuser D: 3.4m Rated wind speed: 11m/s 1kW Model Rotor D: 1.4m Diffuser D: 1.9m Rated wind speed: 11m/s 100kW Model Rotor D: 12.8m Diffuser D: 15.4m Rated wind speed: 12m/s -Passive yaw system -Fixed blade pitch 1kW WL turbine: NHK Robot Cam 1kW Windlens turbine Solar panel(1.1kW) Robot camera system equipped with wind-lens turbine and solar panel. 2012.8.1 A building remains in Watari-cho, south of Sendai after the east Japan tsunami disaster 100kW Noise comparison Blade tip noise reduction works on 100kW Wind-lens turbine as well. 20dB difference! Sound pressure is 10 times smaller! Noise comparison: Windlens turbine is quiet! Wind-lens technology in the water Tidal flow and Current The same flow acceleration principle works in the water. • Density of water is 840 times the air • The streams always flow in the rivers, irrigation canals and in the ocean Generator A water channel experiment carried out at Kyushu University Rivers : Mini-Hydro Advantages of the Wind-lens turbine • Two to five times increase in output power as compared to conventional wind turbines with the same rotor D • Brim-based yaw control • Significant reduction in wind turbine noise • Improved safety • Reduction in interference with Doppler radar • Less frequent bird strikes Offshore hybrid farm experiment The prototype design and a series of scaled model experiments started in 2011. The construction of the actual floating body finished on 2nd of December 2011. The float is moored about 780m offshore in Hakata bay. CG image of the final design Scaled model experiment in a large water tank Google map 18 m Stage 1: Hakata-bay float Diameter : 18m Hub height: 10 m Float weight: 130 ton (140 ton with turbine etc.) Float: Prestressed concrete, semi-submersible Wind turbine: 3 kW x 2 PV panel: 2 kW Mooring : 6 cables with 20 ton anchor block for each Monitoring cable tension for cable #2 (the one takes the max load) Float behavior during extreme conditions The floating body has survived several typhoons including quite large ones in 2012. The maximum wind speed exceeded 50m/s during the season. The Wind-lens power control system safely operated the turbines, and no damages have been found on either turbines or floating body. Roll and yaw angles were constrained within the designed range (5 degrees). Also the maximum tension on the cable with the largest load was 8 ton, well under the spec (max 31.2 ton). Wind and power comparison Data set from a turbine on the float is analyzed and compared to an equivalent system of 3kW Wind-lens turbine installed in Minato Park at the vicinal coast in a distance of 3.7km from the floating platform between 2012 Nov to 2013 Oct. Wind comp. Power comp. Minato park Float Ave. wind speed 3.5m/s 4.3m/s Ave . power 79kWh 164kWh Output power 200%! Stage 2: 1MW offshore hybrid farm Marine farm • • Each side is ~70 m. Each Wind-lens turbine generates 300 kW at the rated wind speed of 12m/s. As a hybrid system, a triangular unit farm produces > 1 MW in total output. Marine farm will be installed in and around it. 300kW Wind-lens turbine: Rotor D: 23m Diffuser D: 26m Nacelle height from the SL. : ~30m Key words: Hybrid and multi purpose Other activities: ●Larger wind turbines: Multi turbine design Less wind-load oscillation amplitude Scaling factor, 1/ 𝑛 smaller mass/weight than single design Joint research plan has started with Thailand and other countries… ●Wind-Solar tower: Diffuser type tower for enhanced power output Low maintenance system Two mechanisms of causing air flow inside of the tower Summary • Wind-lens turbine utilizes a wind acceleration device and achieves 2-5 time output power enhancement. • Due to the Wind-lens structure, the blade tip noise from the turbine is dramatically suppressed. • Compact type diffusers enables an installation of the Wind lens to larger turbines (current largest model is 100kW turbine). • Offshore floating energy farm stage I has been installed for data taking since Dec 2011 and demonstrating great advantage of the offshore wind energy farming. • Current research activities includes, Multi-rotor wind-lens turbine and Wind-Solar tower and more… Thank you for your attention! 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