Validation of Wake Vortex Encounter Simulation Models Using Flight Test Data Assessment of Wake Vortex Safety Dietrich Fischenberg DLR Braunschweig Workshop WakeNet2-Europe, Working Group 5, Hamburg, -11 May 2004
2 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
Statistics of Full Scale Flight Encounter 3 Date Encounter A/C Altitude Encounter flown Flap setting of wake generating A/C DLC-flap setting 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 Cessna Citation FL 150 25 14 const. 22.3.2002 Dornier Do128 FL 0 25 14, 35 const. total 116
Wake Generating Aircraft ATTAS 4 ATTAS with extended flaps smoke generator in action smoke trace, constant DLC flaps smoke trace, oscillating DLC flaps
Encounter Aircraft 5 Dornier Do 128 (TU-BS) 4 flow probes (5 hole probes) 4,2 m 2,3 m Cessna Citation II (NLR) 1 flow probe (vanes)
Encounter Maneuver 6 wake generation 0.5 nm 1.5 nm 3.0 nm smoke trace
Flight Test Encounter Scenario 7 wake generation 0.5 nm 1.5 nm 3.0 nm smoke trace
Do128 Typical Encounter Flow Sensor Measurements 8
The 2 Steps of Encounter Flight Test Data Evaluation 9 step 2 measured flight flight test test data data pilot s control inputs basic basic A/C A/C aero aero model model aerodynamic interaction model model forces, moments + + forces, moments accelerations, s, attitude, altitude, velocity 6-DOF 6-DOF A/C A/C simulation simulation outputs - + model accuracy step 1 wake vortex characteristics step 2: encounter model validation accelerations, s, attitude, altitude, velocity flow measurements flight flight path path reconstruction reconstruction (FPR) (FPR) Vortex model step 1: flow field characterization
Validation Basic Do128 Model - no Wake Vortex Influence measured model output lateral accel. vertical accel. roll pitch 6 M/S 2-4 0 M/S2-25 40-40 30 1 2 3 4 5-0 20 time, s yaw 40 bank -0 pitch yaw -40 0-500 1 2 3 4 5 0 0 20 time, s
Determination of Vortex Model Parameters: Rosenhead - B & H 11 noseboom sensor horizontal velocity vertical velocity measured model output right wing sensor -15-20 15 left wing sensor -5-15 15 distance: 0.8 nm Identified: Γ = 115.3 m 2 /s vertical tail sensor -5-15 20 r C = 0.90 m (=4.2% wing span) -15-0 1 2 3 4 5 6 0 1 2 3 4 5 6 time, s time, s
12 Determination of Vortex Model Parameters: Winckelmans horizontal velocity 20 20 noseboom hit of vortex core sensor vertical velocity measured model output right wing sensor left wing sensor - -30-30 -20 20 distance: 0.6 nm Identified: Γ = 152 m 2 /s r C = 0.22 m (=1% wing span) -15-0 1 2 3 4 5 6 0 1 2 3 4 5 6 time, s time, s
Do128: Comparison of Different Vortex Models 13
14 Aerodynamic Interaction Models Strip Method (SM) ONERA Lifting Surface Method (LSM) TU Berlin
Validation of Strip Method (SM): Simulation of ATTAS/Do128 Wake Vortex Encounters 15 lateral accel. vertical accel. roll pitch 3 M/S2-3 0 M/S 2-20 50-50 Encounter 1: right left Encounter 2: left right -15 0 20 time, s yaw bank pitch yaw 12-12 40-40 -5 200 Encounter 1: right left Encounter 2: left right 140 0 20 time, s measured simulation model output
Validation of Lifting Surface Method (LSM): Simulation of ATTAS/Do128 Wake Vortex Encounter 16 lateral accel. vertical accel. roll pitch 3 M/S2-3 0 M/S 2-20 50-50 Encounter 1: right left Encounter 2: left right -15 0 20 time, s yaw bank pitch yaw 12-12 40-40 -5 200 Encounter 1: right left Encounter 2: left right 140 0 20 time, s measured simulation model output
Summary 17 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.