1. Project Overview
By reducing or avoiding the flow separation on a rotating wind turbine
blade, the performance is increased producing more lift and energy. For this
reason, the short-term goal for this project consists in studying the flow
structure of a rotating plate and trying to identify when is there a stable leading
edge vortex in the blade. This was executed by using dye flow visualization
methods in a water channel at different tip speed ratios with an angle of attack
of 30 degrees. For future studies, with the results obtained, Particle Image
Velocimetry (PIV) methods will be implemented to achieve a more detailed
understanding of the flow structure, including tests with different angles of
attack.
Experiment Set Up
 Test Plate Dimensions - Rectangular with sharp edges, Aspect Ratio – 4,
Span – 4 in., chord – 1 in., radius to tip – 4.25in, Radius to root – 0.25.
 Brushless Motor
 Galil Tools program
 Waterproof nacelle with water suction system.
 Motor assembly on top of the water channel.
 Lighting from bottom and upstream
 Dye Application: Fluoriscine and Elmer’s Multi-Purpose Glue
Parameter Selection
The parameters were chosen based off the data in the research of Flow Structure on a Rotating
Wing: Effect of Steady Incident Flow by M. Bross, C. A. Ozen, and D. Rockwell. When
transforming their parameters to the aspect ratio of the plate used in this project, to achieve the tip
speed ratios and flow velocities, we had to apply these tip speed velocities.
Then, an average of the tip
velocities was taken and with a
MatLab code the free stream
velocity for a specific tip speed
ratio was calculated while
maintaining a similar Reynold’s
number. However, for very low
tip speed ratios, different
parameters were used to because
of the water channel’s pump
limitations.
Bross & Rockwell Paper Transformations to Our Experiment
U Vtip TSR Veff Re Vtip Veff Counts/sec
0 0.618 N/A 0.618 23430 0.805689 0.805689 2387.4
0.05 0.279 5.58 0.28344488 10766 0.385523 0.388751828 4569.49
0.1 0.279 2.79 0.296379824 11257 0.373955 0.387094746 4432.38
0.15 0.279 1.86 0.316766475 12030 0.366819 0.39630314 4347.8
Experimentation with Constant
Angle of Attack of 30 degrees
TSR
Free Stream
Velocity (m/s)
Velocity at
Tip (m/s) Veff m/s Re
1 0.07 0.07 0.09899 2879
1.5 0.07 0.105 0.1262 3669
2 0.1877 0.37543 0.4197 12207
2.5 0.1502 0.37543 0.4044 11759
3 0.1251 0.37543 0.3957 11508
3.5 0.1073 0.37543 0.3905 11355
4 0.0939 0.37543 0.387 11254
4.5 0.0834 0.37543 0.3846 11184
5 0.0751 0.37543 0.3829 11134
5.5 0.0683 0.37543 0.3816 11097
6 0.0626 0.37543 0.3806 11068
7 0.0536 0.37543 0.3792 11029
Results
As the tip speed ratio increases, the flow
separation is smaller and occurs closer to the
root. Also, the leading edge vortex (LEV)
becomes larger with the same increase in tip
speed ratio. However, the most stable LEV is
found with a tip speed ratio of 5. Although, the
vortex is larger with a tip speed ratio of 7, the
vortex sheds almost 3 times faster than the LEV
formed at a tip ratio of 5.
Additionally, more tests with performed with
dye applied at chordwise and spanwise locations
in the plate at different tip speed ratios.
Consequently we are able to obtain a better view
of the flow separation happening in the plate.
Tip Speed Ratio Effects in Flow Separation on a
Rotating Plate
Acknowledgments: Faculty Sponsor, Dr. James Buchholz and Graduate Student Mentor Kevin Wabick.
Reference: Flow structure on a rotating wing: Effect of steady incident flow: M. Bross, C. A. Ozen, and D. Rockwella. Department of Mechanical Engineering and Mechanics, Lehigh University, 356 Packard Laboratory, 19 Memorial Drive
West, Bethlehem, Pennsylvania 18015, USA
(Received 2 November 2012; accepted 8 July 2013; published online 1 August 2013)
By Jan Michael Lopez