Validation of Wake Vortex Encounter Simulation Models
Using Flight Test Data
Dietrich FischenbergDLR Institute of Flight Systems
Braunschweig
WorkshopWakeNet2-Europe, Working Group 5, Hamburg, 10 -11 May 2004
Assessment ofWake Vortex
Safety
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Scope of Presentation
flight tests, measurements, and data
flight test data analysis performed within the S-WAKE project:
• determination of vortex model parameters to characterize vortex flow field
• validation of flight mechanic/aerodynamic interaction models
summary
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Statistics of Full Scale Flight Encounter
Date EncounterA/C
Altitude Encounterflown
Flap setting ofwakegenerating A/C
DLC-flapsetting
14.8.2001 Dornier Do128 FL 95 24 14° const.
15.8.2001 Dornier Do128 FL 95 27 14°, 35° const.
21.8.2001 Dornier Do128 FL 95 15 14°, 1° split,oscillating
15.3.2002 CessnaCitation
FL 150 25 14° const.
22.3.2002 Dornier Do128 FL 100 25 14°, 35° const.
total 116
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Wake Generating Aircraft ATTAS
ATTAS with extended flaps smoke generator in action
smoke trace,oscillating DLC flaps
smoke trace,constant DLC flaps
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Encounter Aircraft
Dornier Do 128 (TU-BS)4 flow probes (5 hole probes)
4,2
m 2,3
mCessna Citation II (NLR)
1 flow probe (vanes)
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Encounter Maneuver
smoke trace
0.5 nmwake
generation1.5 nm
3.0 nm
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Flight Test Encounter Scenario
smoke trace
0.5 nmwake
generation1.5 nm
3.0 nm
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Do128 Typical Encounter Flow Sensor Measurements
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The 2 Steps of Encounter Flight Test Data Evaluation
basicA/C aero
model
basicA/C aero
model
aerodynamic interaction
model
aerodynamic interaction
model
pilot’scontrolinputs
forces,moments
∆ forces, ∆ moments
+
+
6-DOFA/C
simulation
6-DOFA/C
simulation
+
-outputs
accelerations, rates, attitude, altitude, velocity
modelaccuracy
step 2
measuredflight test
data
measuredflight test
data
flow measurements
flightpath
reconstruction(FPR)
flightpath
reconstruction(FPR)
accelerations,rates,
attitude,altitude,velocity
Vortex model
step 2:“encounter model validation“
wake vortexcharacteristicsstep 1
step 1:“flow field characterization“
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Validation Basic Do128 Model - no Wake Vortex Influence
________ measured________ model output
lateralaccel.
verticalaccel.
rollrate
pitchrate
0 20 time, s-10
30-40
40-25
0-4
6
DEG/S
DEG/S
M/S2
M/S 2
1 5432
yawrate
bankangle
pitchangle
yawangle
0 20 time, s100
500-10
10-100
100-40
40DEG/S
DEGDEG
DEG
DEG
1 5432
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Determination of Vortex Model Parameters: Rosenhead - B & H
horizontal velocity vertical velocity
measuredmodeloutput
noseboomsensor
rightwing
sensor
leftwing
sensor
verticaltail
sensor
-15
10
20 15
10
20
-15 -10
10 10
-5 -15
-15
-10
15
-5
m/s
m/s
m/s m/s
m/s
m/s
m/s m/s
time, s time, s10 2 4 63 5 10 2 4 63 5
distance: 0.8 nm
Identified:Γ = 115.3 m2/s
rC = 0.90 m(=4.2% wing span)
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Determination of Vortex Model Parameters: Winckelmans
horizontal velocity vertical velocity
measuredmodeloutput
noseboomsensor
rightwing
sensor
leftwing
sensor
10
-10 -30
20 20
-30 -20
10
m/s
m/s m/s
m/s
m/s m/s
time, s time, s10 2 4 63 5 10 2 4 63 5
-15 -10
20 10
hit of vortex core
distance: 0.6 nm
Identified:Γ = 152 m2/s
rC = 0.22 m(=1% wing span)
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Do128: Comparison of Different Vortex Models
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Aerodynamic Interaction Models
Strip Method (SM)ONERA
Lifting Surface Method (LSM)TU Berlin
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Validation of Strip Method (SM):Simulation of ATTAS/Do128 Wake Vortex Encounters
yawrate
bankangle
pitchangle
yawangle
140
200-5
10-40
40-12
12DEG/S
DEG
DEG
DEG
0 20 time, s
lateralaccel.
verticalaccel.
rollrate
pitchrate
-15
10-50
50-20
0-3
3
DEG/S
DEG/S
M/S 2
M/S2
0 20 time, s
Encounter 1:right left
Encounter 2:left right
Encounter 1:right left
Encounter 2:left right
________ measured________ simulation model output
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Validation of Lifting Surface Method (LSM):Simulation of ATTAS/Do128 Wake Vortex Encounter
Encounter 1:right left
Encounter 2:left right
Encounter 1:right left
Encounter 2:left right
yawrate
bankangle
pitchangle
yawangle
140
200-5
10-40
40-12
12DEG/S
DEG
DEG
DEG
0 20 time, s
lateralaccel.
verticalaccel.
rollrate
pitchrate
-15
10-50
50-20
0-3
3
DEG/S
DEG/S
M/S 2
M/S2
0 20 time, s
________ measured________ simulation model output
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Summary
S-WAKE flight test measurements (116 encounter) are a valuable high quality data base
Flight test data were successfully evaluated with parameter identification and flight path reconstruction techniques to determine parameters of wake vortex models (Rosenhead & Burnham-Hallock, Lamb-Oseen, Winckelmans)
Flight test data were successfully evaluated to validate aerodynamic interaction models (AIMs) for near parallel encounter cases (strip method, lifting surface method)
In general, both AIMs are suitable to simulate wake vortex encounters (especially roll and vertical axes). Overall, both methods show equally good results.