Results of an experimental study are presented on the effectiveness of a vortex generator (VG) in preventing lift-off of a jet-in-cross-flow (JICF). The study is pertinent to film-cooling applications and its relevance to NASA programs is first briefly discussed. In the experiment, the jet issues into the boundary layer at an angle of 20deg to the free-stream. The effect of a triangular, ramp-shaped VG is studied while varying its geometry and location. Detailed flow-field properties are obtained for a case in which the height of the VG and the diameter of the orifice are comparable to the approach boundary layer thickness. The VG produces a streamwise vortex pair with vorticity magnitude three times larger (and of opposite sense) than that found in the JICF alone. Such a VG appears to be most effective in keeping the jet attached to the wall. The effect of parametric variation is studied mostly from surveys ten diameters downstream from the orifice. Results over a range of jet-to-freestream momentum flux ratio (1<J<11) show that the VG has a significant effect even at the highest J covered in the experiment. When the VG height is halved there is a lift-off of the jet. On the other hand, when the height is doubled, the jet core is dissipated due to larger turbulence intensity. Varying the location of the VG, over a distance of three diameters from the orifice, is found to have little impact

Heidmann, James

Rigby, David

Zaman, Khairul

NASA Technical Reports Server

FUNDAMENTAL STUDY OF A JET-IN-CROSSFLOW
INTERACTING WITH A VORTEX GENERATOR FOR FILM
COOLING APPLICATIONS
Abstract
Results of an experimental study are presented on the effectiveness of a vortex generator (VG) in
preventing lift-off of a jet-in-cross-flow (JICF). The study is pertinent to film-cooling applications and its
relevance to NASA programs is first briefly discussed. In the experiment, the jet issues into the boundary
layer at an angle of 20 ° to the free-stream. The effect of a triangular, ramp-shaped VG is studied while
varying its geometry and location. Detailed flow-field properties are obtained for a case in which the
height of the VG and the diameter of the orifice are comparable to the approach boundary layer thickness.
The VG produces a streamwise vortex pair with vorticity magnitude three times larger (and of opposite
sense) than that found in the JICF alone. Such a VG appears to be most effective in keeping the jet
attached to the wall. The effect of parametric variation is studied mostly from surveys ten diameters
downstream from the orifice. Results over a range of jet-to-freestream momentum flux ratio (1< J<11)
show that the VG has a significant effect even at the highest J covered in the experiment. When the VG
height is halved there is a lift-off of the jet. On the other hand, when the height is doubled, the jet core is
dissipated due to larger turbulence intensity. Varying the location of the VG, over a distance of three
diameters from the orifice, is found to have little impact.
https://ntrs.nasa.gov/search.jsp?R=20100042247 2019-08-30T13:50:34+00:00Z
National Aeronautics and Space
Administration
Fundamental Study of a Jet-in-Crossflow Interacting with a
Vortex Generator for Film Cooling Applications
Khairul Zaman 1 , David Rigby2 and James Heidmann 3
Aerospace Engineer
NASA Glenn Research Center	 _	 _	 Pik
wow
( 1 Inlet and Nozzle Branch
2 ASRC Aerospace Corporation
NASA Subsonic Transport System Level Metrics
.... technology for dramatically improving noise, emissions, & performance
N+1 (2015)*** N+2 (2020)*** N+3 (2025)***
R	 $& T'% Technology Benefits Technology Benefits Technology Benefits
TRA(% S)AC% Relative to a Single Aisle Relative to a LargeReference Configuration Twin Aisle Reference
Configuration
Noise
-32 dB -42 dB -71 dB(cum below Stage 4)
LTO NOx Emissions
-60% -75% Better than -75%(below CAEP 6)
Performance:
-33%** -40%** Better than -70%Aircraft Fuel Burn
Performance:
-33% -50% Exploit metroplex* conceptsField Length
***Technology Readiness Level for key technologies = 4-6
** Additional gains may be possible through operational improvements
* Concepts that enable optimal use of runways at multiple airports within the metropolitan area
SFWApproach
- Conduct Discipline-Based Foundational Research
- Investigate Advanced Multi-Discipline-Based Concepts and Technologies
- Reduce Uncertainty in Multi-Disciplinary Design and Analysis Tools and Processes
- Enable Major Changes in Engine Cycle/Airframe Configurations
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
2
Advanced Materials and Structures
A Fuel Burn = - 5%
Aerodynamic Improvements
A Fuel Burn = - 1.5%
Subsystem Improvements
A Fuel Burn < 0.5%
Fuel Burn = 30,900 lbs
Fuel Burn = 39,300 lbs
1998 EIS Technology
-13,100 lbs (-33.3%)
Advanced Aerodynamic Technology
A Fuel Burn = - 15.4%
Subsystem Improvements
^= A 
Fuel Burn < 0.5% Fuel Burn = 26,200 lbs
Advanced Propulsion
A Fuel Burn = - 13.4%
Advanced Materials and Structures
A Fuel Burn = - 4.4%
3
Performance -Fuel Burn - N+1
Fuel Burn = 39,300 lbs
1998 EIS Technology
-8400l bs (-21 %)
"N + 1" Conventional Small Twin
• 162 pax, 2940 nm mission baseline
• Ultra high bypass ratio engines, geared
• Key technology targets:
Increase in turbomachinery component effs.
-25% turbine cooling flow
+50 deg. F compressor exit temp (T3)
+100 deg. F turbine rotor inlet temp (T41)
-15% airframe structure weight
-1% total vehicle drag
-15% hydraulic system weight
"N + 1" Advanced Small Twin
• All technologies listed above plus:
Hybrid Laminar Flow Control
67% upper wing,
50% lower wing,
tail, nacelle
Result = -17% total vehicle drag
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
Advanced Propulsion
A Fuel Burn = - 15%
Materials and Cooling Improvements
. .. ................................ ...... ....... .. .. .... ... . . . . .. .. . . . . . . . . . . . . . . 	 .
Increase in operational temperature of turbine components.	 :YEe'AR;
After Schulz et al, Aero. Sci. Techn.7:2003, p73^80.
	 To _2 ^t_urk^n'e er'i[r^ terripe_r"aturi
 
:o^ie^' recent? years
dI^F^Fortl,,s1985. AGA^![D CP X39_ fc o_Ilectecl, i_n LLak}'minaryria; tii 9;gb),.
Majority of Turbine Temperature Increase Enabled By Cooling Improvements
Fundamental Aeronautics Program 	 4
Subsonic Fixed Wing Project
Coolant location
downstream of hole
Advanced Film Cooling Concepts	 1i\^'' '!
...._..._.	 _._.._......._ .............._.....................................................
rti^t
Round hole jet lift-off	 Anti-Vortex Film Cooling Concept (Heidmann, NASA)
Flow Direction
Front View
Shaped holes (standard practice)Fundamental Aeronautics Program
Subsonic Fixed Wing Project
Top View
Baseline Coolant Coverage Anti-Vortex Coolant Coverage
(hot wall)	 (cool wall)
5
z	 ^
S	 rificed=0.75”
Top view
4
VG x ly orifice Test section floor
-H:.::.:.
. .........:.:.:. .. ... . . ..::. . . . . . ........	 .... .. . .. . . ......7.7. ^...... ......:.7.:.:.......
Side view
Schematic of experimental set-up
Picture with two crossed hot-wires on left
-1	 0	 1	 2	 -2	 -1	 0	 1
z/d	 z/d
Mean velocity at 10 orifice diameters downstream
left: baseline flow, right: with VG
Inclined Jet-in-Crossflow Interacting with a Vortex Generator
Objective:
-- Fundamental study of a vortex generator (VG)
concept to prevent liftoff of jet-in-cross-flow (JICF)
-- Explore concept for advanced turbine film cooling
-- VG is robust in design and may be alternative to
expensive shaped holes
Rationale:
-- VG produces a pair of streamwise vortices opposite
in sign to that of bound-vortex-pair of JICF;
-- Jet liftoff delayed through vorticity cancellation
Approach:
-- Obtain detailed flowfield data including all compo-
nents of mean velocities, turbulence intensities, and
streamwise vorticity
-- Optimize VG geometry and location through
experiment and accompanying CFD
Result:
-- Data on bottom right demonstrate ‘coolant flow’
successfully pulled towards wall
Research team: Khairul Zaman, David Rigby, James
Heidmann
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
6
Single-wire set-up
X-wire set-up
Experimental Facility
S
_t >
U
- H
	
VG
	
y
	
U j
	Test section floor
x
.....................................
.^
..
....,.7.:.:......:.:
..^...
F- L -,♦ 0.754.4---- 2.2 --- - -r
Side view
Schematic of Orifice and VG
Data to be presented are for:
L = 1.91d, S=1.57d and H=0.75d
J = (UD/U)2 = 2
z i
x	 ---
orifice
	
d=0.75
_? .
Top view
Fundamental Aeronautics Program 	 7
Subsonic Fixed Wing Project
Approach boundary layer and orifice exit conditions
Velocities at exit of Orifice
U/U ∞ 	u’/U ∞
0.29
• 0.25	 U=0• 0.21
0.17
Uj 41f/s
0.96
0.92
V V 0	 0.3	 0.6	 0.9
y/d
Approach B.L. profiles
B.L. thickness - VG height
Fundamental Aeronautics Program 	 8
Subsonic Fixed Wing Project
9
Jet penetration
Trajectory of U-peak at z=0
VG effectively pulls and retains the JICF (coolant) close to wall
Fundamental Aeronautics Program 	 10
Subsonic Fixed Wing Project
Turbulence intensity (u’/U ∞ ) contours on x-sectional planes
.-.._. _._ ................................ ......................................... .
Only JICF, No VG
	
Only VG, No JICF	 VG + JICF
_	 . .. .. n 	 n 	 000 004 •008 •013 •017 021
1S	 0.00 0.03 006 009 0.12 0.15	 ^$	 0.00 0.03 0.06 0.09 0.12 0.15 	 15
^	 1	 1
x/d=3.13 T T^	 T
0.5
3
2
x/d=15 T
-2	 -1	 0	 1
zId
Fundamental Aeronautics Program
Subsonic Fixed Wing Project 11
2
x/d=10 T
Streamwise variation of peak turbulence intensity
Turbulence is high for combination of VG and JICF
Causes a faster mixing of the JICF (coolant) as evidenced from U-contours
Fundamental Aeronautics Program 	 12
Subsonic Fixed Wing Project
13
	
Streamwise vorticity ( xd/U ∞ ) contours on x^sectional planes	 ' y
.-.._. _._ ................................ ......................................... .
Only JICF, No VG
	
Only VG, No JICF	 VG + JICF
-	 . . . .	 n 	 . .	 . . . . n 	 -240 -139 •037 •0.98 • 1.99 3.00	 .
	
15	
-120 -079 ^ 0.39 X 0.29 X 0.69, 1.10	 1.5	 -2.60 -1 b4'-0 '4; ' 1
.
.28 	 234 ' 340	 1 5
	
1	 1	 ^	 1
	
x/d=3.13 T	 T	 T	
//^/^^
^
\\\
	
0.5	
Q._	
0.5	 OS
< n-7,0
	
0	 -1	 -0.5	 0	 0.5	 1	 0	 -1	 -0.5	 0	 0.5	 1	 0	 -1	 -0.5	 0	 0.5	 1M:.........: n 	 5...........;i
	 n :.........:J.......	 ...........	 .......
-0.70 -0.38 -0.05	 0.28	 0.60	 -1.90 -1.07	 0.31	 1.14	 1.97	 2.80	 -1.90 -0.94	 0.49	 1.44	 2.40
	
15	 1.5	 1.5
x/d=5
	
T	 ^	 T	 T
	
05	
a ^	
05
	
05
	
1--
	 1.5	 0-1.5	 -1	 -0.5	 0	 0.5	 1	 1.5	 0-1.5	 -1	 -0.5	 0	 0.5	 1	 1.5
-0.	 •0.16 • -0.08 • 0.02 0.10 Oa	 n .............^	 F	 _^^ • n^^ F •r, ^^ n
2
x/d=10
1
0	 -2	 -1	 0	 1	 2
3
2
x/d=15
1
0	 -2	 -1	 0	 1	 2
z!d
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
Variation of streamwise vorticity properties with axial distance
Variation of peak vorticity	 Trajectory of vortex core
VG dominates streamwise vorticity
,- peak about 3 times larger for VG relative to JICF
The job could be done with a smaller VG ?
Fundamental Aeronautics Program 	 14
Subsonic Fixed Wing Project
Effect of varying location of VG relative to orifice
U, u' and x contours on x-sectional plane at x/d=10
x	 U/U ∞ 	u’/U
∞
	 xd/U ∞F-	 n .. 
• • 
. n 	 r:	 • n 	 ^: ..... . . n
0.65 0.73 •0.81 0.88 0.96 1.01	 0.00 0.02 •0.04 •0.06 •0.08 0.10	 -0.60 -0.37 •0.14 •0.17 • 0.40	 0.64
	
2	 2	 2
	
VG tip at T	 T
x/d=0
-2	 -1	 0	 1	 2	 0	
-2	 -1	 0	 1	 2	 -2	 -1	 0	 1	 2
n . . ..... ..... n 	 n 	 ..... ..... n 	 n
. ..... .....	 . . ..	 ....	
. '0'17'	
.
0.65 0.73 0.81 0.88 0.96 1.01	 0.00 0 
.
.02 0.	
.
04 0.06 0
.
.08 0.10	 -0.60 -0	
.
.37 -0.1.4	 . 0.40
.
 0.64
	
2	 2	 2
	
x/d=0.5 T	 ®	 T	 T
	
1	 1	
^	
1
	
0	 -2	 -1	 -0	 1	 2	 0	 -2	 -1	 0	 1	 2-	 0	 -2	 -1	 0	 1	 2
r:.........
.	
n 	 M:.......... n 	 M;.......... n........	 ..........	 .........
0.60 0.70 0.79 0.89 0.99 1.02 	 0.00 0.02 0.04 0.07 0.09 0.11	 -0.70 -0.42 -0.14	 0.34	 0.62
.
 0.90
	
2	 2	 2
Tx/d=2.0	 T
	
1	 1
	
ZZZi	 2 OT
	
0	 -2	 -1	 0	 1	 2	 0	 -2	 -1	 0	 1	 2	 0	 -2	 -1	 0	 1	 2
w. ..........M
	 n
........... n 	 ^. .
......... n
.... ...	 . . .. . .. .	 .	
.	 . . . . . .
0.60 0.70 0.80 0.90 1.00 1.03 	 0.00 0.02 0.04 0.07 0.0
.
9 0.11	
-0.80 -0.46 -0
.
.13	 0.43	 0.76
.
	1.10
	
2	 2	 2
x/d=3.0	 T	 9	 T	 T
	
ZZZI	 9o
	
0	 -2	 -1	 0	 1	 2	 0	 -2	 -1	 0	 1	 2	
-2	 -1	 0	 1	 2
z!d	 z!d	 z/d
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
15
Variation of streamwise vorticity properties at x/d=10
for varying location of VG
Variation of peak vorticity	Trajectory of vortex core
When VG is moved downstream, xG peak increases and spanwise
separation of the pair decreases, expected since VG moves closer to
measurement location
Placement of VG at different x/d made only small difference
Fundamental Aeronautics Program 	 16
Subsonic Fixed Wing Project
J=1W:.	 ... n
0.65 075 •082 •089 •0.96 1 01
J = 1.5
0.70 0.77 '0.84 011 '0199 1.01
W.. J = 3 ... n
0.64 0.73 '0.83 012 '112 1.08
2
U/U
∞
1
0
2
u’/U
∞ a
1
0
2
xd/U ∞
1
0
z/d
U, u’ and x contours at x/d=10
For different J ((Uj/U)2 ); Only JICF, no VG case
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
17
18
U, u’ and 
x 
contours at x/d=10
For different J; VG + JICF case
J = 1
0.60 0.68 0.76 0.85 0.93 1.01
U/U
∞	 2
a
T
1
0	 -2	 -1	 0	 1	 2
zId
n ........... n
0.00 0.02 0.04 0.06 0.08 0.10
u’/U
∞
	
2
T
1
aa^
0	 -2	 -1	 0	 1	 2
z/d
-0 60 -0 38 -0 15 0 15	 0 38	 060
2
xd/U ∞ 1
0	 -2	 -1	 0	 1	 2
zld
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
Effect of J on magnitude and location of U-peak with and w/o VG
Magnitude of U-peak changes little in presence of VG
But location is drawn toward wall even at highest J
Fundamental Aeronautics Program 	 19
Subsonic Fixed Wing Project
Fundamental Aeronautics Program 	 20
Subsonic Fixed Wing Project
CFD: Coolant streamlines - Surface colored by effectiveness
Blowing ratio=1.5, Density ratio=2, J=1.125
• JICF without VG lifts off
• JICF with VG is drawn to the surface and spreads
Fundamental Aeronautics Program
Subsonic Fixed Wing Project 	 21
CFD: Secondary momentum vectors at x/D=5
JICF Alone
	 JICF + VG
Blowing ratio = 1.5
	 Blowing ratio = 1.5
Density ratio = 2.0
	 Density ratio = 2.0
J = 1.125
	 J = 1.125
`'	 ^ L L 1	 s	 '	 ^ 3 Y	 ^`` 0.tt .
V	 f
I LI.
Addition of VG reverses and strengthens vortices as in experiment
Fundamental Aeronautics Program
Subsonic Fixed Wing Project
22
Concluding Remarks	 ' y
VG used effectively pulls and retains the JICF (coolant) close to the wall
Placement of VG at different axial location made only small difference in the
effect
VG used dominates streamwise vorticity; xG peak about 3 times larger for
VG only relative to JICF only
It may be possible to keep the coolant close to the wall with a smaller VG.
Further combined experimental and CFD effort will focus on optimization by
varying geometric parameters of VG.
Fundamental Aeronautics Program 	 23
Subsonic Fixed Wing Project
Fundamental Aeronautics Program
Subsonic Fixed Wing Project 	 24


Fundamental Study of a Jet-in-Cross-Flow Interacting with a Vortex Generator for Film Cooling Applications

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