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AAE 415 – Aerodynamic Design
Final Project Presentation
Large Horizontal-Axis Wind Turbine Design
Ted LightJeff Robinson
December 13, 2003
Outline
• Background– Wind Energy & History– Types of Wind Turbines– Wind Turbine Aerodynamics
• Design Process– Starting Point and Analysis Method
• Results
Wind Energy & History
• Wind energy has been used for thousands of years, for sailing, pumping water, grinding grain, etc.
• In the early 1900s, wind turbines were used to produce direct electric current to small areas
• Oil Crisis of 1970s renewed interest in wind turbines as a cheap, clean, unlimited source of energy
Types of Wind Turbines
“Darrius” Vertical Axis Wind Turbine
Large Horizontal Axis Wind Turbine
Traditional Windmill
Airfoil Aerodynamics
Wind = V0
Rotation = r *
Relative Wind = W
• Wind Speed and Turbine Rotation must be combined to find total velocity that airfoil sections “see”
Desired Airfoil Qualities
For a fixed-pitch, constant speed machine, recommended airfoil qualities at 0.75R are:
– High L/D
– Low clmax near tip reduces tendency to overpower generator in high wind speeds
– Insensitive to surface roughness (bugs, birds, bullets)
Design Process
• CMARC used to analyze designs
• Existing wind turbine with known geometry and performance modeled for baseline comparison
• Assumed constant velocity generator(Power) = (Moment)*(Rotation Rate)
• Variation and Analysis of Designs– Geometric parameters modified
Analysis Strategy
• Start with an existing wind turbine, then modify its geometry
• Geometry varied– Airfoil section– Twist distribution– Chord distribution
• Rotational rate, number of blades and span were held constant
Mod-2 Wind Turbine Specifications
3.45 m 1.43 m
13.7 m
45.7 m
• Diameter = 91.4 m• No. of Blades = 2• Average Wind Speed = 12.5 m/s• Rotation Rate = 17.5 rpm• Airfoil: NACA 23024• Power Output = 2.5 MW
CMARC Inputs
• Rotation rate about x-axis set to that of Mod-2 wind turbine (17.5 rpm)– Many wind turbines are “constant speed”
• Wind Speed set to local average wind speed for Mod-2 (12.5 m/s)
• Baseline geometry emulated Mod-2 geometry, then varied
Results
r/R (1) (2) (3)0 15 14 10
0.25 11.4 11.4 80.5 5.7 7 6
0.75 3.8 3.8 41 2.85 2.85 2
Chord Changesr/R (1) (2) (3)0 6.1 6.0 5.5
0.25 66.7 27.8 83.50.5 83.4 49.5 890.75 93.8 71.3 90
1 111.6 93.0 92
Twist Changes (values in deg from wind axis)
Mod-2 Baseline Model 5816 ---
Mod-A Airfoil Changed to NACA 651-012 5516 -12%Mod-B Airfoil Changed to NACA 65-410 6179 15%Mod-C Airfoil Changed to Althaus AH 93-W-145 2551 -131%Mod-D Chord Change (1) from Mod-B with no sweep 8914 124%Mod-E Chord Change (2) from Mod-B with no sweep 8442 105%Mod-F Chord Change (3) from Mod-B with no sweep 7872 82%Mod-G Chord Change (3) from Mod-B with sweep 9380 143%Mod-H Twist Change (1) from Mod-G 10367 182%Mod-I Twist Change (2) from Mod-G 7849 81%Mod-J Twist Change (3) from Mod-G 7735 77%
Mod-2 Rating Published Power Rating 2500
Model # DescriptionPower (kW)
D from
Baseline
Results
Leading Edge
Root Section
Blade Tip
Airfoil NACA 65-410
r/R Chord (m) Twist (deg)0 10 6.1
0.25 8 66.70.5 6 83.4
0.75 4 93.81 2 111.6