Wake Vortex Encounter Gust Size and Magnitude Flight Data

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Augustus Moody
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1 Wake Vortex Encounter Gust Size and Magnitude Flight Data A P Brown Flight Research Laboratory, NRC Aerospace presented to WakeNet3-Europe 2 nd Major Workshop Developments in wake Turbulence Safety Toulouse, 28 th /29 th June, 21 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

2 Presentation Flight data (NRC program) Context of gust size/rise/fall-lengths and magnitudes (gust peak speeds) Example of flight data Continuous turbulence Rise/fall analysis Discrete (turbulent trailing vortex cores) WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

3 CONTEXT Proceeding to a definition of an acceptable WVE: Requires design & certification of structure, aeroservoelasticity, systems, aerodynamics; in turn Requires definition of WVE gust magnitudes and rise-lengths, for the formulation of design standards:- Discrete gusts, and Continuous gust spectra Combination (superposition)? Not presently required for aircraft gust-load certification WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

4 In which WVE realms: Both following realms are desirable:- Improvement upon existing landing-approach WT separation standards, and Establishment of enroute WT separation standards both involve t WAKE O[4:12] seconds wake vortex trailing pair probably have turbulent cores, may be in significant individual or/and mutual instability state flight data has both dissipative turbulence scale and intensifying turbulent scales, which are more likely to be core instability modes WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

5 3 WVE Gust Size and Magnitude Flight Data EXAMPLE Trailing pair crossplanereferenced vortex-induced wind perturbations w c 2 w a w Z 1 w c w a w Z d s o - s u m, b a s e d u p o n T A S & ψ d s o - s u m, b a s e d u p o n T A S & ψ WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

6 1 3 P S D of longitudinal gus tines s, vortex core travers es Trailing pair crossplane Continuous gust spectra 1 2 continuous gus t P S D (ft/s ) 2 /(rad/ft)) flight data,8-1 nm wake length, 3-9 s ec age FAR2,App.F with U =8 fps with σ σ=8/3. fps s patial frequency (rad/ft) WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

7 1 2 P S D of lateral gus tines s, vortex core travers es WVE Gust Size and Magnitude Flight Data Continuous gust spectra FAR 2 for typical weight/dim - 7, lb transport a/c 1 1 continuous gus t P S D (ft/s ) 2 /(rad/ft)) flight data,8-1 nm wake length, 3-9 s ec age FAR2,App.F with U =8 fps with σ σ=8/3. fps s patial frequency (rad/ft) WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

8 Continuous gust spectra 1 2 P S D of vertical gus tines s, vortex core travers es 1 1 continuous gus t P S D (ft/s ) 2 /(rad/ft)) flight data,8-1 nm wake length, 3-9 s ec age FAR2,App.F with U =8 fps with σ σ=8/3. fps s patial frequency (rad/ft) WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

9 Rise and fall magnitudes & lengths (peaks and troughs counting) of A38 Ris ing gus t Falling gus t Typ M FAR 12.c/66fps ris e-rate x 1 gus t-ris e magnitude ( ) gus t-ris e length (m) WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

10 Rise and fall magnitudes & lengths of normalised 2. A38 normalis ed gus t-ris e magnitude, V T /(Γ/b V ) normalis ed gus t-ris e length, s /b GEN WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

WVE - discrete vortex core traverses: Modelling of gust-rise/fall shape depends upon extent of asymptotic V T rise examine flight data traverses

11 WVE - discrete vortex core traverses: Modelling of gust-rise/fall shape depends upon extent of asymptotic V T rise examine flight data traverses V T () cos Burnham-Hallock line vortex s kewed 1-cos dis tance (m) WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

12 m B-H, Γ= r C =3.794 Rankine, Γ=628. r C =3. WVE Gust WVE Size Gust and Magnitudes/Rise-lengths Flight Data Vortex core traverses: Γ GEN 73 m 2 /s Wake age, t = 3 sec Wake length 7. nm, Γ = 63 m 2 /s advance/recede tails overlay Superposition of mean + turbulent, peak V T > 2 (66 fps) 3 2 poly fit -1m B-H, Γ= r C = Rankine, Γ=628. r C = r C m 1/ r C m 1/ WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

13 poly fit -1m B-H, Γ= r C =.9714 Rankine, Γ=628. r C =3. Rankine, Γ=39.9 r C =3.7 Rankine, Γ=39.9 r C = Vortex core traverse #2: Wake age, t = 8 sec Wake length 8 nm Γ = O[63] m 2 /s Sec features away from core edges 3 2-1m B-H, Γ= r C =.9714 Rankine, Γ=628. r C = Rankine, Γ=39.9 r C =3.7 Rankine, Γ=39.9 r C = r m 1/ r m 1/ 1 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

14 4 3 3 poly fit -1m B-H, Γ= r C =2.144 Rankine, Γ=61.93 r C =2.7 Vortex core traverse #3: Wake age, t = 6 sec Wake length 8.4 nm Γ = O[62] m 2 /s Lower turbulence, B-H models well Rankine, Γ= r C = m B-H, Γ= r C =2.144 Rankine, Γ=61.93 r C = Rankine, Γ= r C = r m 1/ r m 1/ 1 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

15 3 2 B-H, for Γ=628. r C =4. Rankine, Γ=628. r C =4. Vortex core traverse #4: Wake age, t = 68 sec Wake length 9. nm Γ = O[6] m 2 /s large V T near core edge B-H, for Γ=628. r C =4. Rankine, Γ=628. r C = r m 1/ r m 1/ 1 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

16 3 2 poly fit -1m B-H, Γ= r C =1.313 Rankine, Γ= r C =.3774 Vortex core traverse #: Wake age, t = 74 sec Wake length 1.4 nm Γ = O[8] m 2 /s Secondary vortex, V T ~r 1/ profile poly fit -1m B-H, Γ= r C = Rankine, Γ= r C = r m 1/ r m 1/ 1 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

17 2 2 poly fit -1m B-H, Γ= r C =. Vortex core traverse #6: Wake age, t = 76 sec Wake length 1.6 nm Γ = O[7] m 2 /s Secondary vortex 1 Rankine, Γ= r C = poly fit -1m B-H, Γ= r C =. Rankine, Γ= r C = r m 1/ r m 1/ 1 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

18 poly fit -1m B-H, Γ= r C = Rankine, Γ=39.6 r C =2. Vortex core traverse No.7: Wake age, t = 9 sec Wake length, 12.6 nm Γ = O[38] m 2 /s m B-H, Γ= r C = Rankine, Γ=39.6 r C = r C m 1/ r m 1/ 1 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

19 poly fit -1m B-H, Γ= r C =6 Rankine, Γ= r C =6 Vortex core traverse No.8: Wake age, t = 11 sec Wake length, 14.2 nm Γ = O[36] m 2 /s poly fit -1m B-H, Γ= r C = Rankine, Γ= r C = r m 1/ r m 1/ 1 WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

20 Conclusions: WVE, present & future occur with trailing vortices likely turbulent, incl. cores Have considered WVE gust size & magnitude 8-2nm wake survey flight data, from the viewpoints of Continuous turbulence spectra loading, for helices around & through vortices Ώ(v Z ) of the order of magnitude of FAR 2 design limit spectra; and Rise/fall peaks & troughs analysis (typ. For fatigue loading) groupings of gust rise/falls into a number of discrete non-dim rates Possibility of normalising by generator discrete vortex core traverse size/magnitude profiles Examined eight profiles in detail:- for each, mean + turbulent (V T /V T O[-1%) flow superposition evident; peak V T > 66 fps, FAR limit mag. Line vortex (Rankine) model, & Burnham-Hallock model generally (7/8 times) under-estimated V T at core edges for the good ID, core traverse had low turbulence content; Line vortex model captured core edge V T augmentation by sec vortices, implying non-dissipative in nature, core-stability driven? Further examination of existing & future data warranted. WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

21 QUESTIONS? WakeNet, 3 EU, Toulouse, 28 th /29 th June, 21

Wake vortex severity assessment a core element of the safety case. German Aerospace Center DLR

Wake vortex severity assessment a core element of the safety case German Aerospace Center DLR Carsten Schwarz, Klaus-Uwe Hahn - Institute of Flight Systems Frank Holzäpfel, Thomas Gerz - Institute of Atmospheric