etd-tamu-2004C-2-AERO-Chambers

180 Pages·2012·6.1 MB·English

INVESTIGATION OF COMBUSTIVE FLOWS AND
DYNAMIC MESHING IN COMPUTATIONAL FLUID DYNAMICS
A Thesis
by
STEVEN B. CHAMBERS
Submitted to the O–ce of Graduate Studies of
Texas A&M University
in partial fulflllment of the requirements for the degree of
MASTER OF SCIENCE
December 2004
Major Subject: Aerospace Engineering
INVESTIGATION OF COMBUSTIVE FLOWS AND DYNAMIC MESHING IN
COMPUTATIONAL FLUID DYNAMICS
A Thesis
by
STEVEN B. CHAMBERS
Submitted to Texas A&M University
in partial fulflllment of the requirements
for the degree of
MASTER OF SCIENCE
Approved as to style and content by:
Paul G. A. Cizmas Leland A. Carlson
(Chair of Committee) (Member)
Raytcho D. Lazarov Othon K. Rediniotis
(Member) (Member)
Walter E. Haisler
(Head of Department)
December 2004
Major Subject: Aerospace Engineering
iii
ABSTRACT
Investigation of Combustive Flows and
Dynamic Meshing in Computational Fluid Dynamics. (December 2004)
Steven B. Chambers, B.S., Texas A&M University
Chair of Advisory Committee: Dr. Paul G. A. Cizmas
Computational Fluid Dynamics (CFD) is a fleld that is constantly advancing. Its
advances in terms of capabilities are a result of new theories, faster computers, and
new numerical methods. In this thesis, advances in the computational (cid:176)uid dynamic
modeling of moving bodies and combustive (cid:176)ows are investigated. Thus, the basic
theory behind CFD is being extended to solve a new class of problems that are
generally more complex. The flrst chapter that investigates some of the results,
chapter IV, discusses a technique developed to model unsteady aerodynamics with
moving boundariessuch as (cid:176)appingwinged (cid:176)ight. This will include mesh deformation
and (cid:176)uid dynamics theory needed to solve such a complex system. Chapter V will
examine the numerical modeling of a combustive (cid:176)ow. A three dimensional single
vane burner combustion chamber is numerically modeled. Species balance equations
along with rates of reactions are introduced when modeling combustive (cid:176)ows and
these expressions are discussed. A reaction mechanism is validated for use with
in situ reheat simulations. Chapter VI compares numerical results with a laminar
methane (cid:176)ame experiment to further investigate the capabilities of CFD to simulate
a combustive (cid:176)ow. A new method of examining a combustive (cid:176)ow is introduced by
looking at the solutions ability to satisfy the second law of thermodynamics. All
laminar (cid:176)ame simulations are found to be in violation of the entropy inequality.
iv
To Greg and Wendy
v
ACKNOWLEDGMENTS
No proper acknowledgment can be written without thanking my adviser, Dr. Paul
Cizmas. Every step of the way he has been a true mentor and a friend. Long after
this work is forgotten, I will still remember the person he is. I also would like to
thank the members of my committee: Leland Carlson, Raytcho Lazarov and Othon
Rediniotis. They challenged me in ways I had never known or wanted and made me
allthebetterbecauseofit. Additionally, IwouldliketothankDr. JohnSlattery. The
many discussions with him assisted in my understanding of the material. I would like
to thank my peers: Roshawn Bowers, Joaquin Gargolofi, Jason Guarnieri, Kyu-sup
Kim, Aditya Murthi, Josh O’Neil, Celerino Resendiz, Amarnath Sambasivam, Leslie
Weitz, and Tao Yuan. Lastly, I would like to thank my family. Without their love
and support, none of this would be possible.
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NOMENCLATURE
2D Two-dimensional
¡
3D Three-dimensional
¡
a Summation of the entropy inequality expression over
¡
all the cells in violation of the second law
A Pre-exponential factor
r
¡
c Total molar density
¡
C Molar concentration of species j in reaction r
j;r
¡
cm Centimeters
¡
c Constant pressure speciflc heat of species j
p;j
¡
CFD Computational (cid:176)uid dynamics
¡
D Diameter of circular cylinder
¡
D Rate of deformation tensor
¡
~
d Intermediate term deflned on (p.450) of [Slattery]
i
¡
Binary difiusion coe–cient
ij
D ¡
D Matrix of binary difiusion coe–cients
ij
¡
D Difiusion coe–cient for species i in mixture
i;m
¡
D Thermal difiusion coe–cient
T;i
¡
E Activation energy for reaction
r
¡
F(`) Spatial discretized function
¡
~
F Force on mesh node i
i
¡
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~g Gravitational acceleration
¡
h Enthalpy
¡
h0 Enthalpy of formation of species j
j ¡
I Turbulence intensity
¡
I Identity matrix
¡
in Inches
¡
~
J Mass difiusion (cid:176)ux for species i
i
¡
k Turbulent kinetic energy, thermal conductivity
¡
k Boltzmann’s constant
B
¡
k Efiective heat conductivity
eff
¡
k Spring constant between nodes i and j
ij
¡
k Forward rate constant for reaction r
f;r
¡
k Backward rate constant for reaction r
b;r
¡
K Reaction equilibrium constant for reaction r
r
¡
L Hydraulic diameter
¡
m Meters
¡
mm Millimeters
¡
M Molecular mass of species i
i
¡
N Number of chemical species present in the system
¡
n Number of neighboring nodes connected to node i
i
¡
N Number of chemical species in reaction r
r
¡
viii
N Total number of chemical species in one chemical reaction
s
¡
P Pressure
¡
Pa Pascals
¡
P Reduced pressure
R
¡
q Total number of cells that violate the second law of
¡
thermodynamics
r Mass rate of production of species i by chemical reaction r
i;r
¡
R Universal gas constant
¡
^
R Arrhenius molar rate of production of species i in reaction r
i;r
¡
R Species mass rate of production by all chemical reactions
i
¡
Re Reynolds number
¡
Sc Turbulent Schmidt number
t
¡
S Heat energy due to chemical reaction
h
¡
S Arbitrary speciflcation of chemical species i,
i
¡
source term of component i in momentum equation
St Strouhal number
¡
T Temperature
¡
T⁄ Dimensionless temperature
¡
T Reference temperature
ref
¡
UDF User deflned function
¡
U Boundary layer edge velocity
e
¡
ix
U Freestream velocity
1
¡
u Velocity vector using index notation
i
¡
U Mean (cid:176)ow velocity
¡
u0 Root mean square of velocity (cid:176)uctuations
¡
~v Velocity vector
¡
V Cell volume
¡
w Calculation of entropy inequality at a single cell
¡
X Mole fraction for species i
i
¡
Y Mass fraction for species i
i
¡
fi Cell height factor
–
¡
fl Temperature exponent
r
¡
– Cell height
¡
– Ideal cell height
ideal
¡
¢G– Gibbs energy change
¡
¢H– Standard enthalpy change of reaction
¡
¢t Time step
¡
¢~x Displacement of node j
j
¡
† Characteristic energy
¡
~† Intermediate term deflned on (p.449) of [Slattery]
¡
·0 Forward rate exponent of species j in reaction r
j;r ¡
x
·00 Backward rate exponent of species j in reaction r
j;r ¡
(cid:176) Activity coe–cient
B
¡
„ Viscosity
¡
„ Viscosity of species i
i
¡
„ Turbulent viscosity
t
¡
”0 Stoichiometric coe–cient for reactant i in reaction r
i;r ¡
”00 Stoichiometric coe–cient for product i in reaction r
i;r ¡
› Collision integral
D
¡
` Arbitrary scalar quantity
¡
` Values of ` convected through face f
f
¡
‰ Density
¡
(cid:190) Collision diameter
i
¡
¿„„ Viscous stress tensor used within FLUENT
¡
T General expression for stress tensor for a Newtonian (cid:176)uid
¡