INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS GARRY KWAN YUAN 23 AUGUST 2017

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION TABLE OF CONTENTS 01) WHAT ITS ALL ABOUT (some background knowledge) 02) THE GAME PLAN 03) THE RESULTS (and some of the nitty-gritty) 04) WHAT DOES IT ALL MEAN 05) QUESTION TIME INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

WHAT ITS ALL ABOUT (some background knowledge) MSC THESIS PRESENTATION 01 WHAT ITS ALL ABOUT (some background knowledge) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION WHAT ITS ALL ABOUT (some background knowledge) It is about aeroelastic instabilities of wind turbines in idling or parked conditions. There are only two conditions in operation which a wind turbine would be parked or idling, when the wind is either very slow or very fast. INSERT VIDEO OF WIND TURBINE SPINNING FAST THEN BREAKING IN STORM INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION WHAT ITS ALL ABOUT (some background knowledge) It is about aeroelastic instabilities of wind turbines in idling or parked conditions. The significant interaction between an elastic structure and an airflow INSERT VIDEO OF GLIDER FLUTTER INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION WHAT ITS ALL ABOUT (some background knowledge) It is about aeroelastic instabilities of wind turbines in idling or parked conditions. THE QUESTIONS TO CONSIDER 01) Why is this important? 02) Why is the fate of the industry’s future left in the hands of a masters student? INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION 02 The game plan INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE GAME PLAN How can I contribute to the existing body of work? 01) DERIVE 2D ANALYTICAL SOLUTIONS FOR THE AERODYNAMIC DAMPING VALUES OF A BLADE SECTION THAT IS PARKED. 02) PERFORM NUMERICAL SIMULATIONS FOR AN ENTIRE WIND TURBINE. 03) EXTEND THESE NUMERICAL SIMULATIONS TO ACCOUNT FOR MORE REALISTIC LOADING CONDITIONS. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

The results (and some of the nitty-gritty) MSC THESIS PRESENTATION 03 The results (and some of the nitty-gritty) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE GAME PLAN How can I contribute to the existing body of work? 01) DERIVE 2D ANALYTICAL SOLUTIONS FOR THE AERODYNAMIC DAMPING VALUES OF A BLADE SECTION THAT IS PARKED. 02) PERFORM NUMERICAL SIMULATIONS FOR AN ENTIRE WIND TURBINE. 03) EXTEND THESE NUMERICAL SIMULATIONS TO ACCOUNT FOR MORE REALISTIC LOADING CONDITIONS. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping values of airfoil section of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. NACELLE YAW BLADE PITCH ROTOR AZIMUTH INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Equations are adapted from Petersen’s ‘prediction of dynamic loads and induced vibrations in stall’. A quick summary. 𝒄 𝒙𝒙 𝑹 =− 1 2 𝝆𝒄 𝒓𝜴 𝑽 𝒓𝒆𝒍 2 𝒓 2 𝜴 2 + 𝑽 2 𝒓𝜴 𝒄𝒅−𝑽𝒄 𝒅 𝜶 −𝑽𝒄𝒍+ 𝑽 2 𝒓𝜴 𝒄 𝒍 𝜶 𝒄 𝒚𝒚 𝑹 = 1 2 𝝆𝒄 𝒓𝜴 𝑽 𝒓𝒆𝒍 2 𝑽 2 + 𝒓 2 𝜴 2 𝒓𝜴 𝒄𝒅+𝑽𝒄 𝒅 𝜶 +𝑽𝒄𝒍+𝒓𝜴𝒄 𝒍 𝜶 𝒄 𝒙𝒚 𝑹 = 1 2 𝝆𝒄 𝒓𝜴 𝑽 𝒓𝒆𝒍 2 𝑽 2 + 𝒓 2 𝜴 2 𝒓𝜴 𝒄𝒍+𝑽𝒄 𝒍 𝜶 −𝑽𝒄𝒅−𝒓𝜴𝒄 𝒅 𝜶 𝒄 𝒚𝒙 𝑹 = 1 2 𝝆𝒄 𝒓𝜴 𝑽 𝒓𝒆𝒍 2 𝒓 2 𝜴 2 + 𝑽 2 𝒓𝜴 𝒄𝒍+𝑽𝒄 𝒍 𝜶 −𝑽𝒄𝒅+ 𝑽 2 𝒓𝜴 𝒄 𝒅 𝜶 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Equations are adapted from Petersen’s ‘prediction of dynamic loads and induced vibrations in stall’. A quick summary. 𝑐 𝑥𝑥 𝐵 𝑐 𝑥𝑦 𝐵 𝑐 𝑦𝑥 𝐵 𝑐 𝑦𝑦 𝐵 = cos 𝜃 𝑠𝑝 sin 𝜃 𝑠𝑝 − sin 𝜃 𝑠𝑝 cos 𝜃 𝑠𝑝 𝑐 𝑥𝑥 𝑅 𝑐 𝑥𝑦 𝑅 𝑐 𝑦𝑥 𝑅 𝑐 𝑦𝑦 𝑅 cos 𝜃 𝑠𝑝 − sin 𝜃 𝑠𝑝 sin 𝜃 𝑠𝑝 cos 𝜃 𝑠𝑝 𝒄 𝒚𝒚 𝑩 = 𝐬𝐢𝐧 𝟐 𝜽 𝒔𝒑 𝒄 𝒙𝒙 𝑹 + 𝐜𝐨𝐬 𝟐 𝜽 𝒔𝒑 𝒄 𝒚𝒚 𝑹 − 𝐬𝐢𝐧 𝜽 𝒔𝒑 𝐜𝐨𝐬 𝜽 𝒔𝒑 𝒄 𝒙𝒚 𝑹 + 𝒄 𝒚𝒙 𝑹 𝒄 𝒙𝒙 𝑩 = 𝐜𝐨𝐬 𝟐 𝜽 𝒔𝒑 𝒄 𝒙𝒙 𝑹 + 𝐬𝐢𝐧 𝟐 𝜽 𝒔𝒑 𝒄 𝒚𝒚 𝑹 + 𝐬𝐢𝐧 𝜽 𝒔𝒑 𝐜𝐨𝐬 𝜽 𝒔𝒑 𝒄 𝒙𝒚 𝑹 + 𝒄 𝒚𝒙 𝑹 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Adapting Petersen’s equations to be applicable for a non rotating wind turbine blade section. Another quick summary. Rotating section Non rotating section INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Adapting Petersen’s equations to be applicable for a non rotating wind turbine blade section. Another quick summary. 𝑐 𝑥𝑥 𝑅 = 1 2 𝜌𝑐 𝑟𝛺 𝑉 𝑟𝑒𝑙 2 𝑟 2 𝛺 2 + 𝑉 2 𝑟𝛺 𝑐𝑑−𝑉𝑐 𝑑 𝛼 −𝑉𝑐𝑙+ 𝑉 2 𝑟𝛺 𝑐 𝑙 𝛼 𝑐 𝑥𝑥 𝑅 = 1 2 𝑐𝜌 𝑉 𝑖𝑛 𝑉 𝑟𝑒𝑙 2 𝑉 𝑖𝑛 2 + 𝑉 𝑜𝑢𝑡 2 𝑉 𝑖𝑛 𝐶 𝑑 − 𝑉 𝑜𝑢𝑡 𝐶 𝑑 𝛼 − 𝑉 𝑜𝑢𝑡 𝐶 𝑙 + 𝑉 𝑜𝑢𝑡 2 𝑉 𝑖𝑛 𝐶 𝑙 𝛼 𝑐 𝑦𝑦 𝑅 = 1 2 𝑐𝜌 𝑉 𝑖𝑛 𝑉 𝑟𝑒𝑙 2 𝑉 𝑜𝑢𝑡 2 + 𝑉 𝑖𝑛 2 𝑉 𝑖𝑛 𝐶 𝑑 + 𝑉 𝑜𝑢𝑡 𝐶 𝑑 𝛼 + 𝑉 𝑜𝑢𝑡 𝐶 𝑙 + 𝑉 𝑖𝑛 𝐶 𝑙 𝛼 𝑐 𝑦𝑦 𝑅 = 1 2 𝜌𝑐 𝑟𝛺 𝑉 𝑟𝑒𝑙 2 𝑉 2 + 𝑟 2 𝛺 2 𝑟𝛺 𝑐𝑑+𝑉𝑐 𝑑 𝛼 +𝑉𝑐𝑙+𝑟𝛺𝑐 𝑙 𝛼 𝑐 𝑥𝑦 𝑅 = 1 2 𝜌𝑐 𝑟𝛺 𝑉 𝑟𝑒𝑙 2 𝑉 2 + 𝑟 2 𝛺 2 𝑟𝛺 𝑐𝑙+𝑉𝑐 𝑙 𝛼 −𝑉𝑐𝑑−𝑟𝛺𝑐 𝑑 𝛼 𝑐 𝑥𝑦 𝑅 = 1 2 𝑐𝜌 𝑉 𝑖𝑛 𝑉 𝑟𝑒𝑙 2 𝑉 𝑜𝑢𝑡 2 + 𝑉 𝑖𝑛 2 𝑉 𝑖𝑛 𝐶 𝑙 + 𝑉 𝑜𝑢𝑡 𝐶 𝑙 𝛼 − 𝑉 𝑜𝑢𝑡 𝐶 𝑑 − 𝑉 𝑖𝑛 𝐶 𝑑 𝛼 𝑐 𝑦𝑥 𝑅 = 1 2 𝑐𝜌 𝑉 𝑖𝑛 𝑉 𝑟𝑒𝑙 2 𝑉 𝑖𝑛 2 + 𝑉 𝑜𝑢𝑡 2 𝑉 𝑖𝑛 𝐶 𝑙 + 𝑉 𝑜𝑢𝑡 𝐶 𝑑 𝛼 − 𝑉 𝑜𝑢𝑡 𝐶 𝑙 + 𝑉 𝑜𝑢𝑡 2 𝑉 𝑖𝑛 𝐶 𝑑 𝛼 𝑐 𝑦𝑥 𝑅 = 1 2 𝜌𝑐 𝑟𝛺 𝑉 𝑟𝑒𝑙 2 𝑟 2 𝛺 2 + 𝑉 2 𝑟𝛺 𝑐𝑙+𝑉𝑐 𝑙 𝛼 −𝑉𝑐𝑑+ 𝑉 2 𝑟𝛺 𝑐 𝑑 𝛼 Rotating section Non rotating section INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Adapting Petersen’s equations to be applicable for a non rotating wind turbine blade section. One last thing. c chordwise = cos 2 𝛽 𝑐 𝑥𝑥 𝑅 + sin 2 𝛽 𝑐 𝑦𝑦 𝑅 + sin 𝛽 cos 𝛽 𝑐 𝑥𝑦 𝑅 + 𝑐 𝑦𝑥 𝑅 c flatwise = sin 2 𝛽 𝑐 𝑥𝑥 𝑅 + cos 2 𝛽 𝑐 𝑦𝑦 𝑅 − sin 𝛽 cos 𝛽 𝑐 𝑥𝑦 𝑅 + 𝑐 𝑦𝑥 𝑅 c edgewise = cos 2 𝜃 𝑠𝑝 +𝛽 𝑐 𝑥𝑥 𝑅 + sin 2 𝜃 𝑠𝑝 +𝛽 𝑐 𝑦𝑦 𝑅 + sin 𝜃 𝑠𝑝 +𝛽 cos 𝜃 𝑠𝑝 +𝛽 𝑐 𝑥𝑦 𝑅 + 𝑐 𝑦𝑥 𝑅 c flapwise = sin 2 𝜃 𝑠𝑝 +𝛽 𝑐 𝑥𝑥 𝑅 + cos 2 𝜃 𝑠𝑝 +𝛽 𝑐 𝑦𝑦 𝑅 − sin 𝜃 𝑠𝑝 +𝛽 cos 𝜃 𝑠𝑝 +𝛽 𝑐 𝑥𝑦 𝑅 + 𝑐 𝑦𝑥 𝑅 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping values of airfoil section of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. NACELLE YAW BLADE PITCH ROTOR AZIMUTH INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping values of airfoil section of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. 𝑼 𝒊𝒏𝒆𝒓 𝑽 𝒊𝒏𝒆𝒓 𝑾 𝒊𝒏𝒆𝒓 𝟏 𝟎 𝟎 𝟎 𝐜𝐨𝐬 𝝍 𝐬𝐢𝐧 𝝍 𝟎 − 𝐬𝐢𝐧 𝝍 𝐜𝐨𝐬 𝝍 = 𝑼 𝒓𝒐𝒕 𝑽 𝒓𝒐𝒕 𝑾 𝒓𝒐𝒕 𝑼 𝒊𝒏𝒆𝒓 𝑽 𝒊𝒏𝒆𝒓 𝑾 𝒊𝒏𝒆𝒓 = 𝐕 𝐫𝐞𝐥 𝐜𝐨𝐬 𝜸 𝐕 𝐫𝐞𝐥 𝐬𝐢𝐧 𝜸 𝟎 = 𝑽 𝒊𝒏 𝑽 𝒐𝒖𝒕 𝟎 𝜶= 𝐭𝐚𝐧 −𝟏 𝑽 𝒓𝒐𝒕 𝑼 𝒓𝒐𝒕 −𝜷 𝛂=𝟗𝟎°− 𝜽 𝒑 +𝛃 +𝛄 𝛂=𝛄−𝛃 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping values of airfoil section of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Analytical Aerodynamic damping values at various yaw angles At 75% blade span (Blade 1 at 12 o’clock, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) numerical Aerodynamic damping values at various yaw angles Taken from “stability analysis of parked wind turbine blades” INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Analytical Aerodynamic damping values at various ROTOR AZIMUTHS At 75% blade span (30° nacelle yaw, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Analytical Aerodynamic damping values at various blade pitch angles At 75% blade span (30° nacelle yaw, blade 1 at 12 o’clock, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) What are the general conclusions that can be made? 01) SHOWS THAT THERE IS INDEED A THEORETICAL BASIS TO SUPPORT THE POSSIBLITY OF IDLING INSTABILITIES TO OCCUR. 02) GIVES A FEEL OF WHICH SETTINGS ARE MORE PRONE TO INDUCING SUCH INSTABILITIES. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION PART 1 OF 3 DONE! BREAK TIME INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE GAME PLAN How can I contribute to the existing body of work? 01) DERIVE 2D ANALYTICAL SOLUTIONS FOR THE AERODYNAMIC DAMPING VALUES OF A BLADE SECTION THAT IS PARKED. 02) PERFORM NUMERICAL SIMULATIONS FOR AN ENTIRE WIND TURBINE. 03) EXTEND THESE NUMERICAL SIMULATIONS TO ACCOUNT FOR MORE REALISTIC LOADING CONDITIONS. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. NUMERICAL SIMULATIONS ARE RUN IN FOCUS 6, PHATAS PERFORMED IN THE TIME DOMAIN (60° yaw, blade 1 at 12 o’clock, (90° pitch, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. edgewise flapwise (-15° yaw, blade 1 at 12 o’clock, (90° pitch, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

FULL SYSTEM NATURAL FREQUENCIES IN HZ OF THE NREL 5MW REF WIND TURBINE MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. FULL SYSTEM NATURAL FREQUENCIES IN HZ OF THE NREL 5MW REF WIND TURBINE Mode Description FAST ADAMS 1 1st Tower Fore-Aft 0.3240 0.3195 2 1st Tower Side-to-Side 0.3120 0.3164 3 1st Drivetrain Torsion 0.6205 0.6094 4 1st Blade Asymmetric Flapwise Yaw 0.6664 0.6296 5 1st Blade Asymmetric Flapwise Pitch 0.6675 0.6686 6 1st Blade Collective Flap 0.6992 0.7019 7 1st Blade Asymmetric Edgewise Pitch 1.0793 1.0740 8 1st Blade Asymmetric Edgewise Yaw 1.0898 1.0877 9 2nd Blade Asymmetric Flapwise Yaw 1.9337 1.6507 10 2nd Blade Asymmetric Flapwise Pitch 1.9223 1.8558 11 2nd Blade Collective Flap 2.0205 1.9601 12 2nd Tower Fore-Aft 2.9003 2.8590 13 2nd Tower Side-to-Side 2.9361 2.9408 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

FULL SYSTEM NATURAL FREQUENCIES IN HZ OF THE NREL 5MW REF WIND TURBINE MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. FULL SYSTEM NATURAL FREQUENCIES IN HZ OF THE NREL 5MW REF WIND TURBINE Mode Description FAST ADAMS 1 1st Tower Fore-Aft 0.3240 0.3195 2 1st Tower Side-to-Side 0.3120 0.3164 3 1st Drivetrain Torsion 0.6205 0.6094 4 1st Blade Asymmetric Flapwise Yaw 0.6664 0.6296 5 1st Blade Asymmetric Flapwise Pitch 0.6675 0.6686 6 1st Blade Collective Flap 0.6992 0.7019 7 1st Blade Asymmetric Edgewise Pitch 1.0793 1.0740 8 1st Blade Asymmetric Edgewise Yaw 1.0898 1.0877 9 2nd Blade Asymmetric Flapwise Yaw 1.9337 1.6507 10 2nd Blade Asymmetric Flapwise Pitch 1.9223 1.8558 11 2nd Blade Collective Flap 2.0205 1.9601 12 2nd Tower Fore-Aft 2.9003 2.8590 13 2nd Tower Side-to-Side 2.9361 2.9408 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. APPLY A BANDPASS FILTER 20% ABOVE AND BELOW THE AVERAGED 1ST EDGEWISE ASSYMETRIC FREQUENCIES (26° yaw, blade 1 at 12 o’clock, (90° pitch, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. ZOOM IN & FIT 𝑦 𝑓𝑖𝑡 =𝑎 𝑒 𝑏𝑥 +𝑐 𝑒 𝑑𝑥 (60° yaw, blade 1 at 12 o’clock, (90° pitch, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw, rotor azimuth and blade pitch angles. LOGARITHMIC DAMPING 𝛿= ln 𝑦 𝑓𝑖𝑡@ 1 𝑠𝑡 𝑝𝑒𝑎𝑘 𝑓𝑟𝑜𝑚 45𝑠 𝑦 𝑓𝑖𝑡@ 2 𝑛𝑑 𝑝𝑒𝑎𝑘 𝑓𝑟𝑜𝑚 45𝑠 DAMPING RATIO 𝜻= 𝜹 𝟐𝝅 𝟏+ 𝜹 𝟐𝝅 𝟐 (-90° yaw, blade 1 at 12 o’clock, (90° pitch, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw angles. (Blade 1 at 12 o’clock, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw angles. COMPARED AGAINST NREL’S ‘AEROELASTIC INSTABILITIES OF LARGE OFFSHORE AND ONSHORE WIND TURBINES’ SAME WIND TURBINE SAME WIND SPEED SAME BLADE PITCH ANGLE INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various rotor azimuths. (30° yaw, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various blade pitch angles. (30° yaw, Blade 1 at 12 o’clock, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Again, What general conclusions that can be made? 01) GENERALLY GOOD AGREEMENT BETWEEN AGAINST ANALYTICAL RESULTS AND EXISTING LITERATURE. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION PART 2 OF 3 DONE! INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE GAME PLAN How can I contribute to the existing body of work? 01) DERIVE 2D ANALYTICAL SOLUTIONS FOR THE AERODYNAMIC DAMPING VALUES OF A BLADE SECTION THAT IS PARKED. 02) PERFORM NUMERICAL SIMULATIONS FOR AN ENTIRE WIND TURBINE. 03) EXTEND THESE NUMERICAL SIMULATIONS TO ACCOUNT FOR MORE REALISTIC LOADING CONDITIONS. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) finally, we run the numerical simulations in more realistic conditions. The first thing to do is to include unsteady aerodynamics. THIS IS DONE BY USING A DYNAMIC STALL MODEL APPLICABLE REGION BASED ON SNEL ACCOUNTS FOR LAG EFFECT INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) finally, we run the numerical simulations in more realistic conditions. The first thing to do is to include unsteady aerodynamics. SOME EXAMPLES INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw angles with dynamic stall. (Blade 1 at 12 o’clock, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw angles with dynamic stall. (Blade 1 at 12 o’clock, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various rotor azimuths with dynamic stall. (30° yaw, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various blade pitch angles. (30° yaw, Blade 1 at 12 o’clock, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) the inclusion of the dynamic stall model… 01) SHOWS THAT IT WORKS AS EXPECTED IN THE APPLICABLE REGIONS. 02) SHOWS THAT AERODYNAMIC DAMPING IS INCREASED. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) finally, we run the numerical simulations in more realistic conditions. The SECOND thing to do is to include TURBULENCE. IN REALITY THE WIND SPEED IS NOT CONSTANT IN ACCORDANCE WITH IEC 61400-1 DO THE FLUCTUATIONS PREVENT INSTABILITIES OR IS THE WIND SPEED REGION SO WIDE THAT THE INSTABILITIES BECOME MORE SEVERE INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION THE RESULTS (and some of the nitty-gritty) finally, we run the numerical simulations in more realistic conditions. The SECOND thing to do is to include TURBULENCE. μ=0.74m σ=0.12m μ=1.25m σ=0.54m (30° yaw, Blade 1 at 12 o’clock, 90° pitch, mean wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION 04 What does it all mean? INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION WHAT DOES IT ALL MEAN In the end… 01) THE ANALYTICAL SOLUTIONS SHOW THAT THEORETICALLY, SUCH INSTABILITIES ARE POSSIBLE. 02) RESULTS FROM NUMERICAL SIMULATIONS ARE REASONABLE AND AGREE WELL WITH EXISTING LITERATURE AND ANALYTICAL SOLUTIONS. 03) CRITICAL IN THE EDGEWISE DIRECTION. INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION WHAT DOES IT ALL MEAN THANK YOU INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION 05 Questions? INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS Equations are adapted from Petersen’s ‘prediction of dynamic loads and induced vibrations in stall’. A quick summary. 𝑑𝐿 𝑑𝐷 = 1 2 𝜌 𝑉 𝑟𝑒𝑙 𝑟 2 𝑐(𝑟) 𝑐 𝐿 (𝑟,𝛼) 1 2 𝜌 𝑉 𝑟𝑒𝑙 𝑟 2 𝑐(𝑟) 𝑐 𝐷 (𝑟,𝛼) Blade element theory Project the forces onto the axes of the rotor coordinate system 𝐹 𝑥 𝑅 𝐹 𝑦 𝑅 = sin 𝜙 − cos 𝜙 cos 𝜙 sin 𝜙 𝑑𝐿 𝑑𝐷 𝐹 𝑥 𝑅 𝑉 0 +𝛥𝑉, 𝑟𝛺 0 +𝛥𝑟𝛺 = 𝐹 𝑥 𝑅 𝑉 0 , 𝑟𝛺 0 + 𝜕 𝐹 𝑥 𝑅 𝑉 0 , 𝑟𝛺 0 𝜕𝑉 𝛥𝑉+ 𝜕 𝐹 𝑥 𝑅 𝑉 0 , 𝑟𝛺 0 𝜕𝑟𝛺 𝛥𝑟𝛺 Linearized by first order Taylor series expansion of each component at a point of operation 𝐹 𝑦 𝑅 𝑉 0 +𝛥𝑉, 𝑟𝛺 0 +𝛥𝑟𝛺 = 𝐹 𝑦 𝑅 𝑉 0 , 𝑟𝛺 0 + 𝜕 𝐹 𝑦 𝑅 𝑉 0 , 𝑟𝛺 0 𝜕𝑉 𝛥𝑉+ 𝜕 𝐹 𝑦 𝑅 𝑉 0 , 𝑟𝛺 0 𝜕𝑟𝛺 𝛥𝑟𝛺 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

Make the substitutions MSC THESIS PRESENTATION EXTRAS Equations are adapted from Petersen’s ‘prediction of dynamic loads and induced vibrations in stall’. A quick summary. 𝐹 𝑥 𝑅 𝐹 𝑦 𝑅 = 𝐹 𝑥 0 𝑅 𝐹 𝑦 0 𝑅 + 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑉 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑉 𝛥𝑟𝛺 𝛥𝑉 Rearrange equations 𝛥𝑉= − 𝑦 𝑅 = 𝑑 𝑦 𝑅 𝑑𝑡 𝛥𝑟𝛺= 𝑥 𝑅 = 𝑑 𝑥 𝑅 𝑑𝑡 Express increments in velocities in terms of rate of change in displacements 𝐹 𝑥 𝑅 𝐹 𝑦 𝑅 = 𝐹 𝑥 0 𝑅 𝐹 𝑦 0 𝑅 − − 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑉 − 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑉 𝑥 𝑅 𝑦 𝑅 Make the substitutions INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS Equations are adapted from Petersen’s ‘prediction of dynamic loads and induced vibrations in stall’. A quick summary. 𝐹 𝑥 𝑅 𝐹 𝑦 𝑅 = 𝐹 𝑥 0 𝑅 𝐹 𝑦 0 𝑅 − − 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑉 − 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑉 𝑥 𝑅 𝑦 𝑅 𝐹 𝛼 𝑅 = 𝐹 𝛼 0 𝑅 − 𝑐 𝛼 𝑅 𝑢 𝑅 𝑐 𝛼 𝑅 = 𝑐 𝑥𝑥 𝑅 𝑐 𝑥𝑦 𝑅 𝑐 𝑦𝑥 𝑅 𝑐 𝑦𝑦 𝑅 = − 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑥 0 𝑅 𝜕𝑉 − 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑟𝛺 𝜕 𝐹 𝑦 0 𝑅 𝜕𝑉 INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS CL ALPHA vs angle of attack at various yaw angles At 75% blade span (Blade 1 at 12 o’clock, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS CL ALPHA vs angle of attack at various ROTOR AZIMUTHS At 75% blade span (30° nacelle yaw, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS Cl alpha vs angle of attack for various blade pitch angles At 75% blade span (30° nacelle yaw, blade 1 at 12 o’clock, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various yaw angles. (Blade 1 at 12 o’clock, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various rotor azimuths. (30° yaw, all blades pitched at 90°, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS MSC THESIS PRESENTATION EXTRAS Numerical Edgewise aerodynamic damping RATIOS of blades of NREL 5mw ref wind turbine at various blade pitch angles. (30° yaw, Blade 1 at 12 o’clock, wind speed=50ms-1) INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS

μ=1.25m σ=0.54m μ=0.47m σ=0.61m μ=0.98m σ=0.41m μ=0.55m σ=0.50m MSC THESIS PRESENTATION EXTRAS Blade 1 output at 30° yaw, 0 ° azimuth, 90 ° pitch. μ=1.25m σ=0.54m μ=0.47m σ=0.61m μ=0.98m σ=0.41m μ=0.55m σ=0.50m INVESTIGATION OF IDLING INSTABILITIES IN WIND TURBINE SIMULATIONS