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Sādhanā

, 44:86 | Cite as

Development of a potential vortex-hazard index to predict cruise-level wake turbulence encounters

  • J Saravanakumar
  • C Arshad Shameem
  • T N VenkateshEmail author
Article
  • 68 Downloads

Abstract

A pair of counter-rotating trailing vortices formed as a consequence of lift generation poses a potential threat to the encountering aircraft. In recent years, incidents/accidents involving wake turbulence confrontation at cruise altitude are increasing due to increase in the number of super-heavy category aircraft. The vertical separation distance between two airplanes guided by the Federal Aviation Administration (FAA) could be inadequate in certain cases. In this article, a new approach has been proposed to predict the probable area of the persistence of trailing vortices produced by large aircraft. It includes the development of an index with multiple atmospheric effects on the vortices. Also, the impact of the wake from a distinct airplane is incorporated. The performance assessment of the index in predicting the cruise-level wake vortex encounters has been made using various scenarios that happened in the recent past. Weather Research and Forecasting (WRF) model is employed to simulate the atmospheric flow conditions of chosen situations. We found that the method successfully predicts all the cases considered in this study.

Keywords

Aviation weather hazards aircraft wake vortices potential vortex-hazard index cruise-level encounters wake turbulence WRF 

Nomenclature

b

wingspan of the generating aircraft (m)

e

turbulence kinetic energy (J/kg)

g

acceleration due to gravity (\(\hbox {m/s}^2\))

I

atmospheric turbulence intensity percentage

\(k_s\)

constant for shear production

\(l_s\)

\(\Delta z\), length scale for shear production (m)

m

mass of the generating aircraft (kg)

q

measure of the turbulence kinetic energy (m/s)

\(R_{12}\)

initial separation distance between the vortices

(m); for elliptical loading, \((\pi /4)b\)

\(r_{12}\)

half of the initial separation distance between

the vortices (m)

s

distance along the flight path of the generating

aircraft (km)

t

time in UTC

U

magnitude of atmospheric velocities along the

flight path of the generating aircraft (m/s)

\(u_p,v_p,w_p\)

velocity component of wind in x, y and z directions,

respectively, along the flight path of the

generating aircraft (m/s)

\(V_c\)

cruise velocity of the generating aircraft (m/s)

\(V_E\)

cross-wind along the flight path of the

generating aircraft (m/s)

\(V_T\)

tail wind along the flight path of the

generating aircraft (m/s)

w

descent velocity of the vortices at any

given \(\tau \) (m/s)

\(w_0\)

initial descent velocity (m/s)

\(x_c,y_c,z_c\)

centre of the elliptical area enclosing air masses

\(y_1,y_2\)

lateral position of the port and starboard

vortices, respectively

\(z_1,z_2\)

vertical position of the port and starboard

vortices, respectively

\(\Gamma \)

circulation value of the vortices at any

given \(\tau \) (m2/s)

\(\Gamma _0\)

initial circulation value of the vortices

\(\Gamma _1,\Gamma _2\)

circulation value of the port and starboard

vortices, respectively

\(\Theta \)

angle of rotation

\(\theta \)

aircraft heading concerning the positive x-axis

\(\rho _c\)

density at cruise altitude (\(\hbox {kg/m}^3\))

\(\tau \)

time in seconds (s)

\(\tau _{max}\)

maximum time the vortices can

persist in the atmosphere (s)

\(\varphi ,\lambda ,h\)

latitude, longitude and altitude of the

generating aircraft, respectively, at any given t

\(\psi \)

potential vortex-hazard index

\(\Omega \)

angular velocity

Notes

Acknowledgements

This work was carried out as a part of SERB/DST Project Number SB/S4/AS-145/2014. The support is gratefully acknowledged. The authors are thankful to Ms Asha V and Ms K Veena for their support. They also thank NCAR for making WRF available in the public domain and NCEP for providing the FNL datasets. They further thank Prof Joseph Mathew and Dr V Ramesh for their valuable comments. They appreciate the valuable comments and suggestions by the anonymous reviewer, which have led to improvements of this paper.

References

  1. 1.
    Evans J K 2014 An updated examination of aviation accidents associated with turbulence, wind shear and thunderstorm. AMA Report Number 14-14Google Scholar
  2. 2.
    Nelson R C 2006 Trailing vortex wake encounters at altitude—a potential flight safety issue. AIAA Paper 2006-6268Google Scholar
  3. 3.
    Nelson R C 2004 The trailing vortex wake hazard: beyond the takeoff and landing corridors. AIAA 2004-5171Google Scholar
  4. 4.
    Bauer T, Vechtel D, Abdelmoula F and Immisch T 2014 In-flight wake encounter prediction with the wake encounter avoidance and advisory system. AIAA Paper 2014-2333Google Scholar
  5. 5.
    Solch I, Holzapfel F, Abdelmoula F and Vechtel D 2016 Performance of on-board wake vortex prediction systems employing various meteorological data sources. J. Aircr. 53(5): 1505–1516CrossRefGoogle Scholar
  6. 6.
    Federal Aviation Administration 2014 Safety alert for operators (SAFO). SAFO 14007Google Scholar
  7. 7.
    Federal Aviation Administration 2014 Advisory circular. AC No: 90-23GGoogle Scholar
  8. 8.
    Miloud K B, Dghim M, Fellouah H and Ferchichi M 2017 Experimental investigation on the effect of free stream turbulence on wingtip vortices. AIAA 2017-3037Google Scholar
  9. 9.
    Donaldson C duP and Bilanin A J 1975 Vortex wakes of conventional aircraft. AGARD-AG-204Google Scholar
  10. 10.
    Hill F M 1975 A numerical study of the descent of a vortex pair in a stably stratified atmosphere. J. Fluid Mech. 71(1): 1–13CrossRefGoogle Scholar
  11. 11.
    Holzapfel F 2014 Effects of environmental and aircraft parameters on wake vortex behavior. J. Aircr. 51(5): 1490–1500CrossRefGoogle Scholar
  12. 12.
    Delisi D P and Robins R E 2006 Effects of crosswind shear on trailing vortex evolution. AIAA 2006-1075Google Scholar
  13. 13.
    Robins R E and Delisi D D 2006 Modeling crosswind shear effects in NASA’s AVOSS prediction algorithm. In: Proceedings of the 44th AIAA Aerospace Sciences Meeting and Exhibit, AIAA 2006-1076Google Scholar
  14. 14.
    Proctor F H and Ahmad N N 2011 Crosswind shear gradient affect on wake vortices. AIAA 2011-3038Google Scholar
  15. 15.
    Hallock J N and Holzapfel F 2018 A review of recent wake vortex research for increasing airport capacity. Prog. Aerosp. Sci. 98: 27–36CrossRefGoogle Scholar
  16. 16.
    Venkatesh T N, Arshad Shameem C and Saravanakumar J 2017 Study of a possible wake vortex encounter of an aircraft over the Arabian Sea. J. Phys. Conf. Ser. 822(1): 012049CrossRefGoogle Scholar
  17. 17.
    Saravanakumar J, Arshad Shameem C and Venkatesh T N 2016 Development of an aircraft wake vortex model for assessing cruise-level encounters. NAL PD-CTFD/2016/1010Google Scholar
  18. 18.
    Saravanakumar J, Arshad Shameem C and Venkatesh T N 2017 Calculation of a potential vortex hazard index at cruise-level. In: Proceedings of the 19th AeSI Annual CFD Symposium, pp. 168–171Google Scholar
  19. 19.
    Saravanakumar J, Arshad Shameem C and Venkatesh T N 2017 Case studies of cruise-level aircraft wake vortex encounters using the potential vortex-hazard index. NAL PD-CTFD/2017/1017Google Scholar
  20. 20.
    Michalakes J, Dudhia J, Gill D, Henderson T, Klemp J B, Skamarock W C and Wang W 2005 The weather research and forecast model: software architecture and performance. In: Proceedings of the Eleventh ECMWF Workshop on the Use of High Performance Computing in Meteorology Google Scholar
  21. 21.
    BFU 2017 German Federal Bureau of Aircraft accident investigation 2017 interim report. BFU17-0024-2XGoogle Scholar
  22. 22.
  23. 23.
  24. 24.
  25. 25.
  26. 26.
  27. 27.
  28. 28.
  29. 29.
  30. 30.
  31. 31.
    Pilot report about incident on VT-JBU. Private communicationGoogle Scholar

Copyright information

© Indian Academy of Sciences 2019

Authors and Affiliations

  • J Saravanakumar
    • 1
  • C Arshad Shameem
    • 1
  • T N Venkatesh
    • 1
    Email author
  1. 1.CTFD DivisionCSIR-National Aerospace LaboratoriesBengaluruIndia

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