The Aerodynamics of the Knuckleball Pitch

184 Pages·2016·9.16 MB·English

Marquette University
e-Publications@Marquette
Master's Theses (2009 -) Dissertations, Theses, and Professional Projects
The Aerodynamics of the Knuckleball Pitch: An
Experimental Investigation into the Effects that the
Seam and Slow Rotation have on a Baseball
Michael Patrick Morrissey
Marquette University
Recommended Citation
Morrissey, Michael Patrick, "The Aerodynamics of the Knuckleball Pitch: An Experimental Investigation into the Effects that the Seam
and Slow Rotation have on a Baseball" (2009).Master's Theses (2009 -).Paper 8.
http://epublications.marquette.edu/theses_open/8
THE AERODYNAMICS OF THE KNUCKLEBALL PITCH: AN EXPERIMENTAL
INVESTIGATION INTO THE EFFECTS THAT THE SEAM AND SLOW ROTATION
HAVE ON A BASEBALL

by

Michael P. Morrissey, B.S.

A Thesis submitted to the Faculty of the Graduate School,
Marquette University,
in Partial Fulfillment of the Requirements for
the Degree of Master of Science

Milwaukee, Wisconsin

December 2009
ABSTRACT

THE AERODYNAMICS OF THE KNUCKLEBALL PITCH: AN EXPERIMENTAL
INVESTIGATION INTO THE EFFECTS THAT THE SEAM AND SLOW ROTATION
HAVE ON A BASEBALL

Michael P. Morrissey, B.S.

Marquette University, 2009

There has been plenty of research on the fluid dynamic effects on different
spheres, including sports balls, such as baseballs. Baseball pitches have different
velocities, rotation rates and orientations which will cause the baseball to move in
different directions. There has also been plenty of research on the aerodynamics of
curveballs, but not nearly as much on knuckleballs. The difference between the two is
that the knuckleball has a much slower rotation rate and a different initial orientation.
This causes the baseball to “knuckle,” or moving erratically. This pitch in baseball is one
of the hardest to pitch, hit, catch, and umpire. So through various wind tunnel
experiments, an attempt will be made that would predict the movement of the pitch under
these given conditions.
The experimental data includes force balance dynamometry, flow visualization,
and hot film anemometry. The force balance data includes the lift and lateral forces
acting on a two-seam baseball rotating at 50 rpm. The flow visualization presents how
separation on a rotating, two-seam baseball changes position along the surface of the ball
due to rotation and the seams. Lastly, hot film anemometry illustrates how the seams
effect separation during a rotation of the baseball. Together, these experiments illuminate
the complicated interactions the presence of the seam induces, namely for formation of
the turbulent boundary layer juxtaposed against the variations in the location of separated
region.
i

ACKNOWLEDGEMENTS
Michael P. Morrissey, B.S.

I would love to say the credit for this thesis was all mine. However, that would be
a lie. So, in no particular order, I would like to thank the following persons whose
collaboration, support, and participation have developed this piece of work:
A huge thanks goes to family. Without their support and direction, I wouldn‟t be
where I am today. That includes the ability to laugh at everything that I inherited.
Thanks to Shans. Her patience and light-hearted spirit was needed when the
weeks went by too long and the weekends were too short. We have gained more than I
had imagined before I began graduate school. I look forward to reap the rewards from
the past two years in the future.
Thanks to my advisor, Dr. John Borg. First off, thanks for the awesome thesis
topic. I never would have thought that I would be able to study something that I love so
much. Also, before I attended Marquette University, I didn‟t take a single fluid
mechanics class. However, through all the courses and cheerful help he provided, I have
gained a strong interest in fluid dynamics that I would like to carry into my future. I
learned that you can be smart and still be a cool guy with a great sense of humor.
Thanks to my committee members Dr. Jon Koch and Dr. Philip Voglewede.
Their input and help during the crucial parts of my thesis was well appreciated.
Thanks to Ray Hamilton, Tom Silman, and Dave Gibas for all of their help and
input for a major part of my apparatuses.
ii

Thanks to the graduate students I have become close with. That includes: Drew,
who supposedly should take most of the credit of my thesis due to the sheer luck of
everything working in his presence. Abby, for cutting weeks off of my lab time for
taking time out to teach me how to build a hot wire. Johnson, for the distractions needed
when the workload was tough. Aaron, for being my office mate. Sure it may not have
been something that you wanted, but you have to admit…you had fun. Dan, for taking an
effort to understand baseball even though you knew nothing about the game. However,
you did own a Yankees and Brewers hat. Hopefully you will start following them so you
can understand the players I am talking about.
Thanks to Dr. Nelson from the University of Notre Dame for lending me the
helium bubble generator.
Thanks to Marquette University for the opportunity and financial support over the
past two years.
And lastly, thanks to the Chicago Cubs. Even though you have broken my heart
more times than I wanted in a lifetime, and probably will in the future, you provided me
with a great hobby that I will enjoy the rest of my life. After all, you did give me the
chance to watch a no hitter in a city that you should not have been in. Maybe that was
the reason I went to Marquette. But please, instead of next year, can you do it this year?
iii

TABLE OF CONTENTS
ACKNOWLEDGEMENTS .................................................................................. i
LIST OF SYMBOLS ......................................................................................... vii
LIST OF TABLES .............................................................................................. ix
LIST OF FIGURES ..............................................................................................x
CHAPTERS
1. INTRODUCTION ........................................................................................1
1.1. Background of the Knuckleball .....................................................1
1.2. Baseball Terminology ....................................................................3
1.3. Literature Review ...........................................................................5
1.3.1. Aerodynamics ....................................................................5
1.3.2. Baseball Aerodynamics ......................................................6
1.4. Interview with R. A. Dickey ........................................................27
1.5. Purpose and Methodology ...........................................................29
2. EXPERIMENTAL SETUP ........................................................................31
2.1. Baseball/Sphere ............................................................................31
2.2. Force Balance ...............................................................................33
2.2.1. Apparatus .........................................................................34
2.2.2. Calibration ........................................................................41
2.2.3. Data Collection.................................................................43
2.3. Flow Visualization .......................................................................44
2.3.1. Apparatus .........................................................................45
2.3.2. Image Recording and Processing .....................................47
iv

2.4. Hot Film Anemometry .................................................................49
2.4.1. Apparatus .........................................................................52
2.4.1.1. Hot Film Assembly ............................................52
2.4.1.2. Flat Plate Assembly ...........................................56
2.4.1.3. Baseball Taps for Hot Film ................................57
2.4.1.4. Constant Temperature Anemometer ..................58
2.4.2. Calibration ........................................................................59
2.4.3. Data Collection.................................................................61
3. DATA ANALYSIS ....................................................................................66
3.1. Force Balance ...............................................................................66
3.1.1. Comparison to Previously Published Data: Static Ball
Position .............................................................................66
3.1.2. Spinning Ball ....................................................................71
3.1.3. Two-Seam Knuckleball Conditions .................................84
3.2. Flow Visualization .......................................................................89
3.2.1. Match Pre-Existing Data ..................................................89
3.2.2. Knuckleball Conditions ....................................................92
3.3. Hot Film Anemometry .................................................................99
3.3.1. Matlab Analysis .............................................................103
3.3.2. Shear Stress on a Smooth Sphere with a Trip Wire .......103
3.3.3. Shear Stress on the Knuckleball .....................................107
4. CONCLUSION ........................................................................................119
4.1. Final Conclusions .......................................................................119
4.1.1. Force Balance Conclusions ............................................119
v

4.1.2. Flow Visualization Conclusions ....................................120
4.1.3. Hot Film Anemometry Conclusions ..............................121
4.1.4. Summary of Complete Work .........................................122
4.2. Future Work ...............................................................................128
REFERENCES .................................................................................................130
APPENDIX
A-1. LABVIEW PROGRAMS ........................................................................132
A-1.5. Real Time ..................................................................................132
A-1.6. Single Data Collection ...............................................................134
A-1.7. Multiple Data Collection ...........................................................136
A-2. MATLAB PROGRAMS ..........................................................................138
A-2.1. Multiple Exposure Photo ...........................................................138
A-2.2. Statistical Analysis ....................................................................140
A-2.3. Non-Spinning Baseball Statistical Analysis ..............................142
A-2.4. Spinning Baseball Statistical Analysis ......................................144
A-2.5. Movie Compiler .........................................................................149
A-2.6. Tracer Movie Compiler ............................................................151
A-2.7. Hot Film Analysis ......................................................................153
A-2.8. Blasius Profile............................................................................158
A-3. UNCERTAINTY CALCULATIONS .....................................................158
A-3.1. Uncertainty Constants................................................................159
A-3.2. Uncertainty of Lift .....................................................................159
A-3.3. Uncertainty of Shear Stress .......................................................159
vi

A-4. LIST OF PARTS......................................................................................161