phd defense february 18 2011 doug heim v2
TRANSCRIPT
In-Cylinder Investigation of Engine Size- and Speed-Scaling Effects
Student: Doug HeimAdvisor: Jaal Ghandhi
Sponsor: Wisconsin Small Engine Consortium
Ph.D. Thesis Defense
February 18, 2011
Presentation Outline
February 18, 2011 2
• Motivation and Objectives• Literature Review• Experimental Setup• Steady Flow Test Results• Optical Engine Measurements and Analysis• Summary
Motivation
February 18, 2011 3
• Engine development is time consuming and complicated – adapt existing designs.
• Difficulties are magnified when engine size changes considerably from existing designs.
• WSEC companies have limited resources.– Kohler, Mercury Marine, Briggs & Stratton, Harley-
Davidson, Cummins Power Gen
• WSEC companies are interested in how to scale down highly refined engines.
Objectives
February 18, 2011 4
• To study the fundamentals of engine size- and speed-scaling.
• Scaling laws have been proposed in the past.
• Speed-scaling relations have been verified experimentally.
• Size-scaling relations have not.• Increase our understanding of turbulent in-cylinder
flows.
Methodology
February 18, 2011 5
• Build two precisely scaled, single-cylinder optical engines.
• Study the mean and fluctuating velocity during compression until TDC using particle image velocimetry (PIV).
Literature Review: Principle of Similitude
February 18, 2011 6
• Similar engines have their respective parts made of the same material and have proportional linear dimensions.
• Similar engines should have the same turbulence at the same piston speed, which indicates the same rate of combustion (never been shown to date)
Purday, H.F.P.: Diesel Engine Design, D. Van Nostrand Co., New York, 1919.
Lichty, L.C.: Internal Combustion Engines, 5th ed., McGraw-Hill, New York, 1939.
Literature Review: Engine Size-Scaling
February 18, 2011 7
• Three scaled single-cylinder, SI engines.
• Main areas Taylor studied were volumetric efficiency, mean effective pressure, in-cylinder pressure.
Taylor, C.F.: “Effect of Size on the Design and Performance of Internal-Combustion Engines,” Trans ASME, July, 1950.
Literature Review: Engine Size-Scaling
February 18, 2011 8
Volumetric efficiency
mep: work per engine cycle divided by cylinder volume displaced per cycle.
Pressure at same piston speed
Literature Review: Engine Size-Scaling
February 18, 2011 9
• Study shortcomings:• Geometry of intake ports not specified or varied
to study effect of different flows into the engine.
• Study conducted at a time when modern diagnostic methods not available to study flow fields or make turbulence measurements.
Literature Review: Engine Speed-Scaling
February 18, 2011 10
•TDC turbulence intensity versus engine speed is linear.
•Swirl increases turbulence intensity.
Liou, T.-M., and Santavicca, D.A.: “Cycle Resolved Turbulence Measurements in a Ported Engine With and Without Swirl,” SAE paper 830419, SAE Trans, v. 92, 1983.
Literature Review: Engine Speed-Scaling
February 18, 2011 11
Liou, T.-M., Hall, M., Santavicca, D.A., and Bracco, F. V.: “Laser Doppler Velocimetry Measurements in Valved and Ported Engines,” SAE paper 840375, SAE Trans, v. 93, 1984.
•Slope depends on:•Definition of the mean velocity•Engine geometry/intake
•How would two similar engines fall on this graph?
Literature Review: Engine Speed-Scaling
February 18, 2011 12
• Shortcomings of many studies:• Data taken at a limited number of points in the
engine cylinder.
• Geometry of intake ports fixed.• None have verified how the turbulence intensity
scales with engine size.
Small Engine Large Engine
Experimental Setup
February 18, 2011
13
Scale ratio = 1.69
(Dimensions in mm)
Connecting Rod Length
Crank Radius
Connecting Rod to Crank
Radius Ratio
Bore, B Stroke, S Compression Ratio
TDC clearance
Large Engine 144.8 38.0 3.81 82.0 76.0 10.0 8.44
Small Engine 84.0 22.5 3.73 48.6 45.0 10.0 5.00
Experimental Setup
February 18, 2011 14
Port HousingFixtures
Shim Plate Shim Plate
Intake Port
Exhaust Port
Rocker ArmsCamshaft Blocks
Flowbench Intake Horn
Aluminum Base Plate
Spring and Valve
•Intake ports are modular (allow rotation, different ports).
•Valves sit flush with engine head surface.
•Engine cylinder approximates a right cylinder.
Small and large engine heads.
Experimental Setup
February 18, 2011 15
Cylinder Wall
Cylinder Axis
Exhaust Valve
Intake Valve
Intake Port
Shroud
Intake ValveIntake Port
90°
Cylinder Wall
Cylinder Axis
Exhaust Valve
0-degree Orientation (0-deg) 90-degree Orientation (90-deg)
Performance Port (PP)•Higher performance engines
Utility Port (UP)•Lower manufacturing cost
Shrouded Valve (SV)Non-shrouded Valve (NV)
B
H
DI
HI
L
Intake Port
Intake Horn
Swirl AdapterFixture
Impulse TorqueMeter
Honeycomb
D
T
Steady Flow Test Results
February 18, 2011 16
• Similar engines should have similar:• flow coefficients
• swirl coefficients
•SuperFlow 600 flow bench•Transducer Techniques torque sensor•28 inH2O pressure drop•40 seconds
vBf AV
mC
ρ
=
BVm
TC
Bs
8=
2
2)(
4
=
∫
∫IVC
IVO
IVC
IVO
dCA
dCCABS
R
fV
sfV
vs
θ
θ
θ
θ
θ
θπη
Steady Flow Test Results
February 18, 2011 17
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Cf
2402101801501209060300-30
Crank Angle Degrees
PP, 0-deg., SV Large Head Small Head
Large Head, Cf,avg = 0.303Small Head, Cf,avg = 0.299
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
Cs
0.250.200.150.100.050.00
L/D
Performance Port Utility Port
Open Symbol: Small HeadFilled Symbol: Large Head
0-degree Orientation, SV
Large Head Small HeadValve Port Orientation Rs ± uRs Rs ± uRsShrouded Utility 0-degree -3.214 ± 0.032 -2.967 ± 0.065
Performance 0-degree -3.058 ± 0.030 -2.728 ± 0.058
Non-shrouded Utility 0-degree -0.251 ± 0.008 -0.265 ± 0.00890-degree 0.128 ± 0.009 -0.065 ± 0.008
Performance 0-degree -0.234 ± 0.008 -0.054 ± 0.007
90-degree 0.121 ± 0.008 0.045 ± 0.007
•Rs of SV is 12 times greater than NV•Close agreement between small and large head Rs
Particle Image Velocimetry (PIV)
February 18, 2011 18
ImagingMirror
Bowditch Piston
Extension
SapphirePiston
Window
EngineHead
QuartzRing
WindowNd:YAG LASER
•Seed intake with olive oil droplets (~1-2μm).•At TDC, light sheet is nearly equidistant to piston and engine head.
•Large engine: 300, 600, 900, 1200 rpm.•Small engine: 600, 1200, 1800 rpm.•Images processed with TSI Insight3G software.
PIV Field-of-View (FOV)
February 18, 2011 19
Cylinder Wall
Cylinder Axis
Exhaust Valve
Intake Valve
Low-MagnificationFOV
High-MagnificationFOV
SecondHigh-Magnification
FOV
CylinderVisibleArea
•Top view of engine cylinder showing FOVs with respect to engine cylinder for both engines (FOVs scale between two engines)•Low-magnification FOV: 50 cycles of data at crank angles of -90, -45, and TDC.•High-magnification FOV: 200 cycles of data at TDC.
Large Engine17.5mm x 14mmSmall Engine
10.4mm x 8.3mm
Low-Mag. FOV: Swirl Center Location
February 18, 2011 20
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
y/(B
/2)
-0.4 0.0 0.4
x/(B/2)
TDC
90 bTDC
45 bTDC
UP, SV, 0-deg Cylinder Axis
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
y/(B
/2)
-0.4 0.0 0.4
x/(B/2)
TDC
90 bTDC
45 bTDC
UP, NV, 0-deg Cylinder Axis
Utility Port
•Top view of engine cylinder.•Axes made non-dimensional by cylinder radius (B/2).•Open symbols: small engine, filled symbols: large engine.
•Swirl centers at a given crank angle do not vary much over the range of engine speeds.
•The swirl center precesses in time.
•Grouped in the same location in the cylinder at the same crank angle time for both engines.
Normalized Angular Rotation Rate
February 18, 2011 21
6
5
4
3
2
1
0
Ω /
Ω E
ngin
e
-90 -45 0
Crank Angle Degrees
UP, SV, 0-deg
300 rpm 600 rpm 900 rpm 1200 rpm 1800 rpm
6
5
4
3
2
1
0
Ω /
Ω E
ngin
e
-90 -45 0
Crank Angle Degrees
300 rpm 600 rpm 900 rpm 1200 rpm 1800 rpm
UP, NV, 0-deg
Utility PortΩ: angular velocity magnitudeΩEngine: engine angular rotation rate
•At TDC, on average, the normalized angular velocity of the small engine compared to the large engine is lower
28% lower16% lower
•A decreasing trend in angular velocity approaching TDC, which is attributable to viscous losses at the wall.
•The ratio of the cylinder area to volume of the small engine increases by the scaling factor of 1.69 compared to the large engine.
Swirl Ratio Comparison
February 18, 2011 22
•On average, Ω(TDC)/ΩEngine compared
to Rs: -large engine, SV: 19% higher -small engine, SV: 4% lower -NV: 3-7 times higher
•At very low levels of swirl, Rs largely underpredicts the normalized angular velocity.
5
4
3
2
1
0
Ave
rage
Ω(T
DC
) / Ω
Eng
ine
543210Rs
PP, SV PP, NV UP, SV UP, NV One-to-One Line
Ports in 0-deg OrientationOpen Symbol: Small EngineFilled Symbol: Large Engine
Average normalized angular velocity at TDC vs. swirl ratio
Mean, Fluctuating Velocity Calculation
February 18, 2011 23
∑ ==cN
ic
iEA iyxUN
yxU1
, 2,1),,(1
),(
•Ui is the instantaneous velocity
•Nc is the number of cycles•i=1,2 refers to the components of the velocity in the x- and y-directions
2D Instantaneous velocity field
2D wavenumber field
Low pass filter (depends on cutoff frequency, fc)
Low pass (mean) velocity field
2D Fourier Transform
2D Inverse Fourier Transform
cc L
f1=
Ensemble Average: Spatial-Average:
.2,1),(),(),( =−= iyxUyxUyxu iii
The fluctuating velocity is defined as:
High-Mag. FOV: Turbulence Intensity
February 18, 2011 24
.)},(),({1
),(' 22
1
21 yxuyxu
Nyxu
cN
c
+= ∑
x [mm] [m/s]
y [m
m]
5 10 15
-12
-10
-8
-6
-4
-2
3
3.5
4
4.5
x [mm] [m/s]
y [m
m]
2 4 6 8 10 12 14 16
-12
-10
-8
-6
-4
-2
1.2
1.4
1.6
1.8
2
2.2
x [mm] [m/s]
y [m
m]
5 10 15
-12
-10
-8
-6
-4
-2
1.2
1.4
1.6
1.8
2
2.2
Ensemble Average Method
Higher u’ since swirl center precesses.
Spatial-Average Method
Edge effects.
Throw away edge data.
5
4
3
2
1
0
< u
' >E
nsem
ble
Ave
rage
[m
/s]
543210Vmps [m/s]
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
Open Symbols: Small EngineFilled Symbols: Large Engine
Turbulence Intensity: E.A.
February 18, 2011 25
Liou, T.-M., Hall, M., Santavicca, D.A., and Bracco, F. V.: “Laser Doppler Velocimetry Measurements in Valved and Ported Engines,” SAE paper 840375, SAE Trans, v. 93, 1984.
Non-shrouded
Shrouded
1-D <u’>: our data divided by 21/2
Turbulence Intensity: S.A.
February 18, 2011 26
5
4
3
2
1
0
< u
' >S
patia
l-Ave
rage
[m
/s]
543210Vmps [m/s]
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
Open Symbols: Small EngineFilled Symbols: Large Engine
fc*hTDC = 1.7
5
4
3
2
1
0
< u
' >S
patia
l-Ave
rage
[m
/s]
543210Vmps [m/s]
Open Symbols: Small EngineFilled Symbols: Large Engine
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
fc*hTDC = 0.7
•Spatial-average <u’> depends on fc=1/Lc.
•Data collapse well with hTDC: TDC clearance:-Small Engine: 5 mm-Large Engine: 8.4 mm
Turbulence Intensity: S.A.
February 18, 2011 27
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
< u
' >S
patia
l-Ave
rage
/ V
mps
1.21.00.80.60.40.20.0fc [mm
-1]
Ensemble Average
PP, 0º, SV PP, 0º, NV PP, 90º, NV UP, 0º, SV UP, 0º, NV UP, 90º, NV
Open Symbols: Small EngineFilled Symbols: Large Engine
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
< u
' >S
patia
l-Ave
rage
/ V
mps
86420fc*hTDC
Ensemble Average
PP, 0º, SV PP, 0º, NV PP, 90º, NV UP, 0º, SV UP, 0º, NV UP, 90º, NV
Open Symbols: Small EngineFilled Symbols: Large Engine
Non-shrouded Shrouded
•Linear trend slopes collapse well with hTDC.
0.1
2
3
4
5
6
7
89
1
< u
' >S
patia
l-Ave
rage
/ <
u' >
Ens
embl
e A
vera
ge
3 4 5 6 7 81
2 3 4 5 6 7 810
fc*hTDC
PP, 0º, SV PP, 0º, NV PP, 90º, NV UP, 0º, SV UP, 0º, NV UP, 90º, NV
Open Symbols: Small EngineFilled Symbols: Large Engine
Correlation Coefficient
February 18, 2011 28
)()0(
)()0()(
22 ruu
ruur
ji
jiij
⋅
⋅=ρ
Distance, r
x, y
Transverse ρ22
(perpendicular to the axis):
Distance, r
)0(iu )(rui
Longitudinal ρ11
(parallel to the axis):
x, y
)(rui)0(iu
Correlation Coefficient: High Pass Velocity, κ(cutoff)=1256.6[rad/m]
x [mm] [m/s]
y [m
m]
2 4 6 8 10 12 14 16
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
14
)0(iu)(rui
)0(iu)(rui
Single-sided(horizontal):
Double-sided(horizontal): )(rui
Integral Lengthscales
February 18, 2011 29
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
ρ11
121086420
Δy [mm]
Double-sided Single-sided Lc = 5 mm Lc = 10 mm Lc = 15 mm
Open Symbol: Ensemble-averagedFilled Symbol: Spatial-averaged, Double-sided
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
ρ22
121086420
Δy [mm]
Double-sided Single-sided Lc = 5 mm Lc = 10 mm Lc = 15 mm
Open Symbol: Ensemble-averagedFilled Symbol: Spatial-averaged, Double-sided
)exp(2
1)exp(2
1 xdxd
cxbxb
aR ∆⋅−
∆⋅−+∆⋅−
∆⋅−=
drL ∫∞
=0
1111 ρ drL ∫∞
=0
2222 ρ
•Little difference in E.A. double- or single-sided methods.
Best-fit curve (SAE Paper 880381) used to extend ρ11 to calculate L11:
Integral Lengthscales (measure of the larger eddies):
Normalized Integral Lengthscales: E.A.
February 18, 2011 30
10
8
6
4
2
0
Lii
[mm
]
3.53.02.52.01.51.00.5Vmps [m/s]
L11, Vertical L22, Vertical L11, Horizontal L22, Horizontal
UP, SV, 0-degOpen Symbol: Small EngineFilled Symbol: Large Engine
1.0
0.8
0.6
0.4
0.2
0.0
Lii
/ hT
DC
3.53.02.52.01.51.00.5Vmps [m/s]
L11, Vertical L22, Vertical L11, Horizontal L22, Horizontal
UP, SV, 0-degOpen Symbol: Small EngineFilled Symbol: Large Engine
•Longitudinal and transverse integral lengthscales versus mean piston speed in the vertical and horizontal directions using the ensemble average method.
Normalize by hTDC
•Lengthscales relatively constant with Vmps.•Similar lengthscales between SV and NV cases.
Normalized Integral Lengthscales: E.A.
February 18, 2011 31
•Good agreement in vertical and horizontal directions: indication of isotropy in the plane.
1.0
0.8
0.6
0.4
0.2
0.0
L ii (
Ver
tical
) / h
TD
C
1.00.80.60.40.20.0Lii (Horizontal) / hTDC
L11
L22
One-to-One Line
Open Symbol: Small EngineFilled Symbol: Large Engine
•Non-dimensional integral lengthscales for all engine conditions and speeds in the vertical versus horizontal directions using the ensemble average method.
Scatter in L11 due to best-fit curve.
0.6
0.5
0.4
0.3
0.2
0.1
0.0
L22
/ h
TD
C
0.60.50.40.30.20.10.0L11 / 2*hTDC
Open Symbol: Small EngineFilled Symbol: Large Engine
PP, SV, 0-deg, UP, SV, 0-deg PP, NV, 0-deg, UP, NV, 0-deg PP, NV, 90-deg, UP, NV, 90-deg One-to-One Line
•Isotropic turbulence (L22/ L11 = 0.50).
Modified Integral Lengthscales: E.A.
February 18, 2011 32
•L11* integrated directly from correlation data (does not use best-fit curve) up to a
distance equal to the height of the FOV in both directions.
1.0
0.8
0.6
0.4
0.2
0.0
L 11* (
Ver
tical
) / h
TD
C
1.00.80.60.40.20.0
L11* (Horizontal) / hTDC
Open Symbol: Small EngineFilled Symbol: Large Engine
One-to-One Line
1.0
0.8
0.6
0.4
0.2
0.0
L ii (
Ver
tical
) / h
TD
C
1.00.80.60.40.20.0Lii (Horizontal) / hTDC
L11
L22
One-to-One Line
Open Symbol: Small EngineFilled Symbol: Large Engine
•There is close agreement between the lengthscales in either direction, indicating a high level of isotropy, and the difference between the small and large engine data appear smaller.
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
ρ11
121086420
Δy [mm]
Double-sided Single-sided Lc = 5 mm Lc = 10 mm Lc = 15 mm
Open Symbol: Ensemble-averagedFilled Symbol: Spatial-averaged, Double-sided
Integrate to here.
Normalized Integral Lengthscales: S.A.
February 18, 2011 33
0.30
0.25
0.20
0.15
0.10
0.05
0.00
L ii (
Hor
izon
tal)
/ h T
DC
5 6 7 81
2 3 4 5 6 7 810
fc*hTDC
UP, NV, 0-deg
L11
L22
0.30
0.25
0.20
0.15
0.10
0.05
0.00
L ii (
Ver
tica
l) /
h TD
C
5 6 7 81
2 3 4 5 6 7 810
fc*hTDC
UP, NV, 0-deg
L11
L22
•Very little difference with engine speed (similar to E.A. data).•Again, close agreement between the engines when the data are made non-dimensional by hTDC.
•L11 still calculated using best-fit equation (some waviness).•The transverse lengthscales in both the vertical and horizontal directions give very similar results for a given engine condition and are quite consistent comparing all conditions.
x [mm] [m 2/s2]
y [m
m]
2 4 6 8 10 12 14 16
-12
-10
-8
-6
-4
-2
5
10
15
20
25
30
35
40
45
50
55
Energy Spectra Analysis
February 18, 2011 34
.2
3)(
2
1 22 ⋅+⋅= vuk
Turbulent kinetic energy
Fast Fourier Transform (FFT) of a row
Complex Conjugate of FFT of adjacent row
multiplied by
=Energy Spectrum vs. Wavenumber Plot
Average energy spectra over all rows and engine cycles
Energy Spectra Analysis
February 18, 2011 35
Iterative process that picks turbulence Reynolds number, Re£ (or £ since k measured):
ηκεκ ffCE £3/53/2)( −=
Relation between Re£ and Kolmogorov (η) lengthscale, characteristic of the smallest turbulent motions.
3/422/1
£
£ £Re
===ηενν
kk
.1)(
)(1
2
21
111 κκκ
κκκ
κ
dE
E ∫∞
−=
κκκπ
dE
uL ∫
∞
=0
21
11
)(
2
calculates Pope’s model (3-D) spectrum:
then calculates best-fit model (1-D) spectrum (by varying £ ):
L11 is calculated using E(κ):
Pope, S.: Turbulent Flows, Cambridge University Press, Cambridge, UK, 2000.
Energy Spectra Analysis: E.A.
February 18, 2011 36
Ensemble average method
Deviation from model at small separation distances(~2x PIV interrogation size).
105
106
107
108
109
1010
1011
1012
E11
(κ1)
/(εν
5 )1/4
0.0012 4 6 8
0.012 4 6 8
0.12 4 6 8
1κ1η
300 rpm 600 rpm 900 rpm 1200 rpm
UP, SV, 0-degVertical Direction
Model, 300 rpm Model, 1200 rpm Slope -5/3
Large Engine
105
106
107
108
109
1010
1011
1012
E11
(κ1)
/(εν
5 )1/4
0.0012 4 6 8
0.012 4 6 8
0.12 4 6 8
1κ1η
600 rpm 1200 rpm 1800 rpm
UP, SV, 0-degVertical Direction
Model, 600 rpm Model, 1800 rpm Slope -5/3
Small Engine
Large inertial subrange at higher RPMs.
Energy Spectra Analysis, L11: E.A.
February 18, 2011 37
0.6
0.5
0.4
0.3
0.2
0.1
0.0
L 11
/ hT
DC
3.53.02.52.01.51.00.5Vmps [m/s]
UP, SV, 0-deg
Vertical Horizontal
0.6
0.5
0.4
0.3
0.2
0.1
0.0
L 11
/ hT
DC
3.53.02.52.01.51.00.5Vmps [m/s]
UP, NV, 0-deg
Vertical Horizontal
Open symbols: small engine, filled symbols: large engine.
Utility Port, SV
•Lengthscales relatively constant with Vmps.•Similar lengthscales between SV and NV cases.•Close agreement between small and large engines.•Same conclusions based on spatial-average data.
Utility Port, NV
Energy Spectra Analysis, η: E.A.
February 18, 2011 38
40
30
20
10
0
η [μ
m]
3.53.02.52.01.51.00.5Vmps [m/s]
UP, SV, 0-deg
Vertical Horizontal
40
30
20
10
0
η [μ
m]
3.53.02.52.01.51.00.5Vmps [m/s]
UP, NV, 0-deg
Vertical Horizontal
•η decreases monotonically with engine speed. •Ports with SV compared to NV exhibit smaller η at same Vmps. •η between small and large engines are roughly the same at a given Vmps.•Same conclusions based on spatial-average data.
Open symbols: small engine, filled symbols: large engine.
Utility Port, SV Utility Port, NV
Taylor-scale Reynolds number, Rλ: E.A.
February 18, 2011 39
£Re3
20=λR
cCD
VBZ
avgf
mps
,2
2
=
Inlet valve Mach index (modified Vmps):
Livengood, J.C., and Stanitz, J.B.: “The Effect of Inlet-Valve Design, Size, and Lift on the Air Capacity and Output of a Four-Stroke Engine,” NACA Tech. Notes, no. 915, 1943.
B: cylinder boreD: intake valve inner seat diameterc: speed of soundCf,avg: mass-average flow coefficient
Taylor-scale Reynolds number found from spectral analysis turbulence Reynolds number:
Taylor-scale Reynolds number, Rλ: E.A.
February 18, 2011 40
180
160
140
120
100
80
60
40
20
Rλ
0.200.150.100.05
Z
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
Ensemble Average MethodVertical Direction
180
160
140
120
100
80
60
40
20
Rλ(
Larg
e E
ngin
e), R
λ(S
mal
l Eng
ine)
*1.6
9
0.200.150.100.05
Z
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
Ensemble Average MethodVertical Direction
•Open symbols: small engine, filled symbols: large engine.•Z found from steady flow testing, if relation holds for more intake port configurations, would be a good predictive tool.•Reynolds number is:
Visc. Kin.
*Re
VelocityLength=
Turbulence Intensity vs. Z: E.A. & S.A.
February 18, 2011 41
•Turbulence intensity (velocity-scale) collapses with Z for all engine conditions.
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
< u
' >E
nsem
ble
Ave
rage
[m/s
]
0.250.200.150.100.050.00
Z
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
Open Symbol: Small EngineFilled Symbol: Large Engine
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
< u
' >S
patia
l-Ave
rag
e [m
/s]
0.250.200.150.100.050.00
Z
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
Open Symbol: Small EngineFilled Symbol: Large Engine
fc*hTDC = 0.74.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
< u
' >S
patia
l-Ave
rage
[m/s
]
0.250.200.150.100.050.00
Z
PP, SV, 0-deg PP, NV, 0-deg PP, NV, 90-deg UP, SV, 0-deg UP, NV, 0-deg UP, NV, 90-deg
Open Symbol: Small EngineFilled Symbol: Large Engine
fc*hTDC = 1.7
Ensemble average Spatial-average
Summary
February 18, 2011 42
•Sufficient similarity was achieved as evidenced by steady flow testing.
•Swirl center locations tracked similarly between small and large engines.
•Using either ensemble- or spatial-average method: -<u’ > versus Vmps was similar between the engines. -Similar lengthscales in vertical and horizontal directions: isotropic turbulence in plane of measurement. -L11, L22 constant versus Vmps: integral length scale is controlled by the engine geometry. -η is similar between engines at same Vmps: controlled by the Reynolds number and Lii.
Summary
February 18, 2011 43
•Everything collapses well between the engines with hTDC: -L11, L22 normalized by hTDC are similar between engines (correlation and spectral analyses). -Spatial-average comparisons made at same fc*hTDC are similar between engines (<u’>, L11, L22).
•Velocity-scales between engines collapse well with Z.
Thank You
February 18, 2011 44
•Questions or comments?