ADVANCES IN AERODYNAMICS OF WIND TURBINE BLADES

Transcription

1 ADVANCES IN AERODYNAMICS OF WIND TURBINE BLADES Herning / October 3 / 2017 By Jesper Madsen Chief Engineer, Aerodynamics & Acoustics WIND ENERGY DENMARK Annual Event 2017

2 Agenda 1. Aerodynamic design and developments 2. Innovative tip designs 3. LM Vortex Generator Mk II 2

3 Aerodynamic blade design considerations 3

4 Aerodynamic Developments LM Serrations Focus areas: Low-Noise performance Blade design Devices Aerodynamic tailoring: Wide variation in LM-Airfoil characteristics covers requirements from small on-shore turbines to ultra-long offshore blades Blade optimization Leading Edge Erosion: Aerodynamic impact of eroded blade Erosion protection systems Devices LM T-Spoiler Serrations (acoustics) Vortex Generators T-spoiler (root performance) 4

5 Conventional Blade Tip Innovative Tip Designs Objectives: Reduction of Turbine Wake to improve total windfarm yield Optimize blade tip aerodynamics Reduction of Noise Turbulators ECN Patented Winglet

6 Tip Extension Field Installation and Testing Results: Increase in power output between 5% to 6% at wind speeds between 6 m/s and 9 m/s for conventional blade tip extension. Extending blade accounts for about 4% power increase remainder is optimization in shape.

7 LM Vortex Generator Mk II Continuous Improvement 7

8 Vortex generators improve blade performance by reducing flow separation Without VGs With VGs Low AoA Clean surface flow is separating VGs maintain attached flow Smooth airflow Vortex airflow Max. lift AoA Boundary layer separated Boundary layer attached Stall AoA Uncontrolled turbulence Controlled vortices Compared to a clean blade, VG s typically improves AEP by 0.5% 1% 8

9 LM Vortex Generators Mk II Mk II consists of a single vane on base plate Vanes are mounted on top of blade surface using a tape interface Panel-VG flush-mounted in groove OLD VG s are available in different sizes, so range of applications can be covered Bonding process is covered by international published patent application NEW Material changed to a tougher, more UV stable plastic 9

10 LM Vortex Generator s Mk II Single Fin VG design philosophy completely re-engineered Reliable performance predictions for wide range of airfoil thicknesses, VG configurations, combinations with other Add-Ons obtained from LM Wind tunnel tests Optimal and Robust VG design (geometry and configuration) understanding obtained from exhaustive wind tunnel testing MKII VG s Close up View Some Tested Geometries MKII VG s On an Airfoil in LM Wind Tunnel Performance coefficients from wind tunnel test 10

11 Experimental Optimization of VG Parameters Experimental results from LM Wind Power Low Speed Wind Tunnel (LM LSWT) measurements LM wind tunnel Objective: reduction in drag along with increased or same lift and delayed stall Parameters: Foot plate shape and thickness Chord wise placement Fin geometry Triangular Height (h) Length (l) Configuration: Spacing between pairs (z) Spacing between fins (s) Fin angle (β) Some results are presented in next slides 11

12 Effect of chord wise location VGs closer to the leading edge of the profile has highest increment in the Cl But the same time the increment in the Cd is also more 12

13 Effect of VG height VG with lower height performing better in terms of C lmax and AoA-C lmax and also drag h/c=2% is too high 13

14 Effect of VG spacing z/h=3 has highest increment in Cl (with more Cd) z/h=5 has high Cl/Cd ratio over wider AOA range z/h=7 has highest maximum Cl/Cd (also better than clean) 14

15 Automated Design Tools VG positioning on blade surface Several checks are built in: Aerodynamic force Centrifugal force Different sizes Blade surface curvature VG angle Mould Marks Etc. 15

16 LM Vortex Generator s Mk II Continuous Improvement project to improve the existing LM VG offering along with Improved Aerodynamics Improved Reliability Simplified and Robust installation process Enables service / retro-fit offerings Completely re-designed approach having single fins in an integrated mounting system with focusing on each of the above aspects Exhaustively Tested and Validated designs for performance 16

17 Thank you for your time Contact details: Head quarters: Jesper Madsen LM Wind Power Chief Engineer Jupitervej 6 Aerodynamics & Acoustics 6000 Kolding Denmark Tel Tel Mob Fax E jema@lmwindpower.com E info@lmwindpower.com W lmwindpower.com Note: The contents of this presentation are confidential and may not be copied, distributed, published or reproduced in whole or in part, or disclosed or distributed by recipients to any other person. 17