Akaydin, H. Dogus

Pandya, Shishir A.

NASA Technical Reports Server

Implementation	of	a	Body	Force	Model
into	OVERFLOW	for	Propulsor Simulations*
Applied	Modeling	and	Simulation	Seminar	– 19	October	2017
Advanced	Supercomputing	Division,	Computational	Aerosciences Branch
NASA	Ames	Research	Center
Shishir A.	Pandya
Aerospace	Engineer
NASA	Ames	Research	Center
H.	Doğuş Akaydın
Senior	Research	Scientist/Engineer
Science	and	Technology	Corporation	
at	NASA	Ames	Research	Center
current
previous
*Paper:	AIAA-2017-3572
https://ntrs.nasa.gov/search.jsp?R=20180000806 2019-08-30T13:43:16+00:00Z
/602
NASA	is	actively	sponsoring	research	and	development	of	
cleaner,	less	noisy	and	more	efficient	transport	aircraft
NASA	Advanced	Air	Vehicles	Program,	AATT	(Advanced	Air	Transport	Technology)	Project	Briefing
/603
An	overview	of	the	state	of	the	art:
plan
19601950 2010t ?
Progress	in	commercial	transport	aircraft	has	been	driven	mainly	by
- Engines	(became	more	efficient,	more	powerful	and	more	reliable)
- Composite	structures	(became	more	reliable)	
- Control	surfaces	and	avionics	(became	more	sophisticated)
Airframe	integration,	however,	lagged:	Thin-tube	fuselages	and	wing-mounted	engines	are	
still	the	state	of the	art.
/604
One	of	the	concepts:	The	D8	“Double	Bubble”	Aircraft
Aurora	Flight	Sciences,	Inc.	www.aurora.aero
MIT:	Lead	the	research,	design	the	aircraft,	perform	wind	tunnel	tests
Aurora	Flight	Sciences:	Build	wind	tunnel	models	and	flight	demonstrators
Pratt	&	Whitney:	Develop	the	engines
NASA:	Sponsor	the	project,	provide	wind	tunnel	and	computer	time	for	advanced	analysis
Aurora	Flight	Sciences	+	MIT	+	Pratt	&	Whitney	+	NASA
/60
How	does	Boundary	Layer	Ingestion	work?
5Uranga et	al.,	Preliminary	Experimental	Assessment	of	the	Boundary	Layer	Ingestion	Benefit	for	the	D8	Aircraft,	AIAA-2014-0906
Drela,	Development	of	the	D8	Transport	Configuration,	2011,	AIAA-2011-3970
Drela,	Power	Balance	in	Aerodynamic	Flows,	2009,	AIAA	Journal	47(7)
Instead	of	accelerating	freestream,	the	propulsors accelerate	the	fluid	that	was	
decelerated	by	the	body.	This	reduces	the	total	form	drag.
/606
>30%	reduction	in	fuel	burn	due	to	the	synergistic	integration
of	airframe	components
Optimized
engines
Newer
engines
D8	fuse.,
p-tail
Slow	to
M=0.72
BLI*
R
e
la
ti
ve
	F
u
e
l	
B
u
rn
Integrated
engines
Podded
engines
D8	variant:
*BLI:	Boundary	Layer	Ingestion
Uranga et	al.,	Preliminary	Experimental	Assessment	of	the	Boundary	Layer	Ingestion	Benefit	for	the	D8	Aircraft,	AIAA-2014-0906
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Greitzer et	al.,	N+3	Aircraft	Concept	Designs	and	Trade	Studies.	Volume	1,	2010,	NASA	CR-2010-216794/VOL1
B737-800
/60
The	D8	aircraft	in	wind	tunnel
7Pandya,	External	Aerodynamics	Simulations	for	the	MIT	D8	“Double-Bubble”	Aircraft	Design,	2012,	ICCFD7-4304
Tests	14x22ft	Wind	Tunnel	at	NASA	Langley	Research	Center
CFD	(Computational	Fluid	Dynamics)	simulations	of	the	model	in	the	wind	tunnel
M∞≈0.088
Uranga et	al.,	Preliminary	Experimental	Assessment	of	the	Boundary	Layer	Ingestion	Benefit	for	the	D8	Aircraft,	AIAA-2014-0906
z
x
/60
Evidence	of	BLI	benefit	through	CFD	and	wind	tunnel	tests
8
! !⇥!⇤ !⇥!⌅ !⇥!⇧ !⇥!⌃ !⇥⌥ !⇥⌥⇤
(!⇥! 
(!⇥!⌅
(!⇥!⌦
(!⇥!⇤
(!⇥!⌥
!
!⇥!⌥
!⇥!⇤
!⇥!⌦
!⇥!⌅
!⇥! 
↵
,
-
↵
.
!
!
✏⇣⌘⌘✓⌘◆.,
56⌫✓⇠⇡⇢⌫✓⌘◆.,
✏⇣⌘⌘✓⌘◆↵;⌧
56⌫✓⇠⇡⇢⌫✓⌘◆↵;⌧
DCPk=	-9%
DCPk=	-8%
cruise
Wind	tunnel	tests	show	an	8%	± 0.7%	
reduction	in	power	to	sustain	cruise.
CFD	predicts	a	9%	reduction.
Uranga et	al.,	Preliminary	Experimental	Assessment	of	the	Boundary	Layer	Ingestion	Benefit	for	the	D8	Aircraft,	AIAA-2014-0906
Greitzer et	al.,	Aircraft	and	Technology	Concepts	for	an	N+3	Subsonic	Transport	– Phase	2.	Final	Review,	Dec.	2014
Pandya et	al.,	Computational	Assessment	of	the	Boundary	Layer	Ingesting	Nacelle	Design	of	the	D8	Aircraft,	AIAA-2014-0907
/60
The	application:	Boundary	Layer	Ingestion	(BLI)	on	D8	aircraft
9
Ingested 
boundary 
layer
/60
The	application:	Boundary	Layer	Ingestion	(BLI)	on	D8	aircraft
10
Ingested 
boundary 
layer
Uniform 
static 
pressure 
jump
Previous method:
Uniform static 
pressure jump
z
x
(No jump applied on r, T)
/60
Literature	on	Propulsor Modeling
11
Variants	of	actuator	disk	or	blade	element	models
Helicopter	rotors	&	wind	turbine	applications
Fejtek and	Roberts	[1992]
Zori and	Rajagopalan [1995]		
Chaffin	and	Berry	[1997]		-->	Two	versions	are	already	in	Overflow
O’Brien	and	Smith	[2005]
… many	others.
/60
Literature	on	Propulsor Modeling
12
Variants	of	actuator	disk	or	blade	element	models
Helicopter	rotors	&	wind	turbine	applications
Fejtek and	Roberts	[1992]
Zori and	Rajagopalan [1995]		
Chaffin	and	Berry	[1997]		-->	Two	versions	are	already	in	Overflow
O’Brien	and	Smith	[2005]
… many	others.
Turbomachine	applications
Joo and	Hynes	[1997]	
Kim	et	al.	[1999]
...
/60
Literature	on	Propulsor Modeling
13
Variants	of	actuator	disk	or	blade	element	models
Helicopter	rotors	&	wind	turbine	applications
Fejtek and	Roberts	[1992]
Zori and	Rajagopalan [1995]		
Chaffin	and	Berry	[1997]		-->	Two	versions	are	already	in	Overflow
O’Brien	and	Smith	[2005]
… many	others.
Turbomachine	applications
Joo and	Hynes	[1997]	
Kim	et	al.	[1999]
...
A	particular	series	of	“body-force”	approaches	for	turbomachines
Marble	[1964]
...
Gong	et	al.	[1998]
Defoe	and	Spakovszky [2013]
Peters	et	al.	[2014]
Hall	et	al.	[2017]
/60
The	implemented	body	force	model	by	Hall	et	al.
14
Hall	et	al.	“Analysis	of	Fan	Stage	Conceptual	Design	Attributes	for	Boundary	Layer	Ingestion”,	2017,	ASME	J.	Turbomach.	
/60
The	implemented	body	force	model	by	Hall	et	al.
15
Hall	et	al.	“Analysis	of	Fan	Stage	Conceptual	Design	Attributes	for	Boundary	Layer	Ingestion”,	2017,	ASME	J.	Turbomach.	
/60
The	implemented	body	force	model	by	Hall	et	al.
16
Hall	et	al.	“Analysis	of	Fan	Stage	Conceptual	Design	Attributes	for	Boundary	Layer	Ingestion”,	2017,	ASME	J.	Turbomach.	
/60
The	implemented	body	force	model	by	Hall	et	al.
17
Hall	et	al.	“Analysis	of	Fan	Stage	Conceptual	Design	Attributes	for	Boundary	Layer	Ingestion”,	2017,	ASME	J.	Turbomach.	
(Isentropic flow turning)
/60
Implementation	of	the	body	force	model
18
Y
X
Z
1. Import:
Import the surface 
definition of one 
of the blades
/60
Implementation	of	the	body	force	model
19
1. Import:
Y
X
Z
Y
Z
X
qc
rc
nc
QcPc
2. Extract:
Extract the 
camber surface of 
the blade
/60
Implementation	of	the	body	force	model
20
2. Extract: 3. Flatten:
Y
X
Z
Y
Z
X
qc
rc
nc
Qc
QXY
nXY
PXY
Pc
1. Import
Flatten the camber 
surface on Z=0 
plane
/60
Implementation	of	the	body	force	model
21
2. Extract: 3. Flatten:
Y
X
Z
Y
Z
X
qc
rc
nc
Qc
QXY
nXY
PXY
Pc
4. Extend:1. Import
Extend for a proper 
overlap with 
neighboring grids
/60
Implementation	of	the	body	force	model
22
2. Extract: 3. Flatten: 5. Revolve:
Y
X
Z
4. Extend:
Y
Z
X
Dq
Dq
Dq
qc
rc
nc
Qc
QXY
nXY
PXY
Pc
K=2
K=3
…
1. Import
Revolve that to make 
an axisymmetric 
volume grid
/60
Implementation	of	the	body	force	model
23
2. Extract: 3. Flatten: 5. Revolve:
Y
X
Z
4. Extend:
6. Rotate:
1. Import
z
x
y
X
Z
Y
a
pitch
toe
f
Rotate the whole grid for 
pitch and toe angles
/60
Implementation	of	the	body	force	model
24
2. Extract: 3. Flatten: 5. Revolve:
Y
X
Z
4. Extend:
6. Rotate:
1. Import
z
x
y
X
Z
Y
a
pitch
toe
f
Save the orientation 
metrics in a file
7. Save:
r
nx
ny
nz
nq
Qx
Qy
Qz
/60
Implementation	of	the	body	force	model
25
z
x
y
X
Z
Y
a
pitch
toe
f
2. Extract: 3. Flatten: 5. Revolve:
Y
X
Z
4. Extend:
6. Rotate: 7. Save: 8. Read in Overflow, compute the 
source terms at each iteration r
nx
ny
nz
nq
Qx
Qy
Qz
1. Import
Now NS equations 
(not Euler equations) 
/60
W
Rotor grid
Apply
body force,
W≠0
Don’t apply
body force
Apply
body force, 
W=0
Don’t apply
Body force
Stator grid
Tip clearance
Application	of	the	Body	Force	Model
26
/60
The	Tools	and	Methods
27
Nichols	and	Buning,	Users	Manual	for	OVERFLOW	2.2,	https://overflow.larc.nasa.gov
Grid	Generation:	Chimera	Grid	Tools	(CGT)
Steps	1	to	7	are	automated	by	routines	added	to	CGT	codebase
Solver:	Overflow	2.2l
An	implicit	RANS	solver	for	body-fitted structured	overset	grid	systems
Simulations	here	used	
• Diagonalized approximate	factorization	scheme	[Pulliam	and	Chaussee 1981]
• Central	difference	in	Euler	terms
• Steady-state	simulations	with	constant	CFL	number
• Matrix	dissipation
• Spalart Allmaras (SA)	turbulence	model	(SA-noft2	implementation	in	Overflow)
• Body	force	method	grids	and	metric	files	are	automatically	split
• No	multigrid	when	the	body	force	model	is	used
• Jacobians	of	source	terms	are	not	added	to	left	hand	side
(Hence	no	low	Mach	preconditioning	when	the	body	force	model	is	used)
Chan,	Gomez,	Rogers	and	Buning,	Best	Practices	in	Overset	Grid	Generation,	2002,	AIAA-2002-3191
/60
Test	Cases
28
A	stand-alone	Source	Diagnostics	Test	(SDT)	
fan	with	R4	rotor	blades
/60
Test	Cases
29
A	stand-alone	Source	Diagnostics	Test	(SDT)	
fan	with	R4	rotor	blades
A	stand-alone	TF8000	propulsor
/60
Test	Cases
30
A	stand-alone	Source	Diagnostics	Test	(SDT)	
fan	with	R4	rotor	blades
A	stand-alone	TF8000	propulsor
The	D8	aircraft	model	in	a	wind	tunnel
/60
22 
rotor 
blades
26 
stator 
blades
nacelle
hub
l = 372 cm
d/2=56 cm
x
y
W
Source	Diagnostics	Test	(SDT)	fan	with	R4	Rotors
31
M∞=0.1
Envia,	E.,	“Fan	Noise	Source	Diagnostic	Test	
Completed	and	Documented,”	
NASA	Tech.	Memo.	TM-2003-211990
/60
22 
rotor 
blades
nacelle
hub
l = 372 cm
d/2=56 cm
35l
x
y
W
Rotor 
grid
Stator 
grid
Tip clearance = 0.5 mm
L0
L1
L2
…L12
Source	Diagnostics	Test	(SDT)	fan	with	R4	Rotors
32
M∞=0.1
Envia,	E.,	“Fan	Noise	Source	Diagnostic	Test	
Completed	and	Documented,”	
NASA	Tech.	Memo.	TM-2003-211990
35	million	vertices,	y+≈1
4	to	8	hours	on	128	Haswell	cores
Full	convergence	with	body	force	model
Partial	convergence	with	pressure	jump
26 
stator 
blades
/60
SDT	fan	results
33
uniform pressure jumpbody force
Vz/a∞
Swirl
/60
SDT	fan	results
34
Vz/a∞
uniform pressure jumpbody force
Swirl
Static Pressure
/60
SDT	fan	results
35
Vz/a∞
uniform pressure jumpbody force
Swirl
Static Pressure
Total Pressure
/60
SDT	fan	results
36
Vz/a∞
uniform pressure jumpbody force
Swirl
Static Pressure
Total Pressure
Entropy
/60
SDT	fan	results
37
uniform pressure jumpbody force
Swirl
Static Pressure
Total Pressure
Entropy
Mach number
/60
SDT	fan	results
38
uniform pressure jumpbody force
Streamlines
/60
SDT	fan	results
39
Station 1
x=43.2 cm
Station 2
x=51.7 cmr
/60
SDT	fan	results
40
7,808 rpm 12,657 rpm
Experiment
(phase-avg.)
Experiment
(mean of phase-avg.)
Simulation
(body force model)
SDT campaign at NASA Glenn Research Center
POC: Dr. Ed Envia
Station 1
x=43.2 cm
Station 2
x=51.7 cmr
/60
SDT	fan	results
41
7,808 rpm 12,657 rpm
Station 1
x=43.2 cm
Station 2
x=51.7 cmr
Experiment
(phase-avg.)
Experiment
(mean of phase-avg.)
Simulation
(body force model)
hub
casing
r
[c
m
]
Vx [m/s]
Station 1 Station 2
/60
SDT	fan	results
42
7,808 rpm 12,657 rpm
Station 1
x=43.2 cm
Station 2
x=51.7 cmr
Experiment
(phase-avg.)
Experiment
(mean of phase-avg.)
Simulation
(body force model)
Vq [m/s]
hub
casing
r
[c
m
]
Vx [m/s]
r
[c
m
]
Station 1 Station 2
/60
SDT	fan	results
43
7,808 rpm
Station 1
x=43.2 cm
Station 2
x=51.7 cmr
Experiment
(phase-avg.)
Experiment
(mean of phase-avg.)
Simulation
(body force model)
at Station 1, W=12,657 rpm �"# [m/s] �"$ [m/s] Po,1 / Po,∞
Experiment 171 138 1.509
Body Force Model 172 133 1.491
Vq [m/s]
hub
casing
r
[c
m
]
Vx [m/s]
r
[c
m
]
Station 1 Station 2
Hughes	et	al.,	2005
12,657 rpm
/60
The	D8	aircraft	in	wind	tunnel
44Pandya,	External	Aerodynamics	Simulations	for	the	MIT	D8	“Double-Bubble”	Aircraft	Design,	2012,	ICCFD7-4304
Tests	14x22ft	Wind	Tunnel	at	NASA	Langley	Research	Center
CFD	(Computational	Fluid	Dynamics)	simulations	of	the	model	in	the	wind	tunnel
M∞≈0.088
Uranga et	al.,	Preliminary	Experimental	Assessment	of	the	Boundary	Layer	Ingestion	Benefit	for	the	D8	Aircraft,	AIAA-2014-0906
z
x
/60
l = 29.2 cm
5 rotor 
blades
4 stator 
blades
nacelle
hubd/2= 7.2 cm
x
y
W
TF8000	propulsor on	D8
45
z
x
200	million	vertices,	y+≈1
30	to	40	hours	on	800	Haswell	cores	
TF8000	propulsor
D8	aircraft	in	wind	tunnel	
/60
TF8000	propulsor on	D8	-- Results
46
uniform pressure jumpbody force
Static Pressure
/60
TF8000	propulsor on	D8	-- Results
47
uniform pressure jumpbody force
Static Pressure
Mach number
M
/60
TF8000	propulsor on	D8	-- Results
48
uniform pressure jumpbody force
Static Pressure
Mach number
M
Total Pressure
CP0
/60
TF8000	propulsor on	D8	-- Results
49
DCP0
DCP0=CP0,body force - CP0,pressure jump
/60
TF8000	propulsor on	D8	-- Results
50
z
x
/60
TF8000	propulsor on	D8	-- Results
51
z
z
x
Experimental	data	inferred	from	Uranga et	al.,	2014
(11,100 rpm)
/60
TF8000	propulsor on	D8	-- Results
52
z
z
x
Experimental	data	inferred	from	Uranga et	al.,	2014
(11,100 rpm)
/60
TF8000	propulsor on	D8	-- Results
53
z
x
Experimental	data	inferred	from	Uranga et	al.,	2014
z
(11,100 rpm)
/6054Experimental	data	inferred	from	Uranga et	al.,	2014
TF8000	propulsor on	D8	-- Results
/60
! !⇥!⇤ !⇥!⌅ !⇥!⇧ !⇥!⌃ !⇥⌥ !⇥⌥⇤
(!⇥! 
(!⇥!⌅
(!⇥!⌦
(!⇥!⇤
(!⇥!⌥
!
!⇥!⌥
!⇥!⇤
!⇥!⌦
!⇥!⌅
!⇥! 
↵
,
-
↵
.
!
!
✏⇣⌘⌘✓⌘◆.,
56⌫✓⇠⇡⇢⌫✓⌘◆.,
✏⇣⌘⌘✓⌘◆↵;⌧
56⌫✓⇠⇡⇢⌫✓⌘◆↵;⌧
DCPk=	-9%
DCPk=	-8%
cruise
55Experimental	data	inferred	from	Uranga et	al.,	2014
TF8000	propulsor on	D8	-- Results
/60
TF8000	propulsor on	D8	– Swirl	Effects
56
Vy/a∞
uniform pressure jumpbody force
Swirl
/60
TF8000	propulsor on	D8	-- Results
57
Vy/a∞
uniform pressure jumpbody force
Swirl
/60
TF8000	propulsor on	D8	-- Results
58
Vy/a∞x1
pressure jump model
body force model
uniform pressure jumpbody force
Swirl
/60
TF8000	propulsor on	D8	-- Results
59
Vy/a∞x1
z
[c
m
]
casing
fuselage
Vy/V∞Vx/V∞ Vz/V∞
pressure jump model
body force model
hub
x1=2.79 m:
(fan face)
uniform pressure jumpbody force
Swirl
/60
TF8000	propulsor on	D8	-- Results
60
x2
Vy/a∞
z
[c
m
]
Vy/V∞Vx/V∞ Vz/V∞
x2=2.67 m:
(0.88d upstream)
pressure jump model
body force model
uniform pressure jumpbody force
Swirl
/60
Summary	&	Discussion
61
• A body	force	model	with	blade	loading	by	Hall	et	al.	was	successfully	
implemented	in	the	Overflow	solver.	
• Generation	of	grids	and	blade	orientation	metrics	were	automated.	
• The	model	predicted	integrated	quantities	within	a	few	percent	on	SDT	with	R4	
rotor	blades.
• The	body	force	model	provided	detailed	insights	on	the	buildup	of	mechanical	
power	throughout	the	propulsor.
• Demonstrated	the	need	for	an	experimental	data	set	on	an	isolated	BLI	fan.
• Further	work	would	include	adding	compressibility,	blade	blockage	and	endwall
corrections	into	the	model.
• Further	work	would	also	include	implementing	propulsor models	of	various	
fidelities	to	assess	the	modeling	fidelity	sufficient	for	a	given	modeling	goal.	
/60
Acknowledgements
62
• Dr.	David	K.	Hall	of	the	MIT	Gas	Turbine	Laboratory	provided	a	
description	of	the	source	term	computation	algorithm.	
• Dr.	Edmane Envia of	NASA	Glenn	Research	Center	provided	the	
SDT	aerodynamic	data	and	geometry	definition	files.	
• NASA	Advanced	Air	Transport	Technology	(AATT)	project	provided	
the	funding	for	this	work.	
• NASA	Advanced	Supercomputing	(NAS)	Division	at	NASA	Ames	
Research	Center	provided	computing	resources.


Implementation of a Body Force Model into OVERFLOW for Propulsor Simulations

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