CFD ANALYSIS OF THE EFFECT OF PARABOLIC TAPER DISTRIBUTION OF AN UNTWISTED HELICOPTER ROTOR BLADE

The effect of parabolic taper distribution along the span of a helicopter rotor blade is analyzed in terms of the rotor thrust, torque and Figure of Merit. Various maximum chord length values are investigated. The Reynolds Averaged Navier-Stokes computations are done using the FINE/Turbo flow solver developed by NUMECA International. The Spalart-Allmaras turbulence model is used to calculate the eddy viscosity. The baseline blade is selected as the Caradonna-Tung rotor blade. Different blade shapes were generated by setting the maximum chord length at different spanwise locations for the same planform area as the baseline blade. Three optimum cases are observed: maximum Figure of Merit, maximum thrust for the baseline Figure of Merit and maximum Figure of Merit for the baseline thrust. Those optimum cases are noticed when the maximum chord length is 1.3 times the baseline blade chord length.

PARABOLİK SİVRİLME DAĞILIMININ BURULMASIZ BİR HELİKOPTER ROTOR PALİ ÜZERİNDEKİ ETKİSİNİN HAD ANALİZİ

Bir helikopter rotor palinin açıklığı boyunca parabolik olarak değişen sivrilme dağılımının etkisi rotor itkisi, torku ve verim ölçüsü cinsinden incelenmiştir. Birçok farklı maksimum veter uzunluğu değerleri kullanılmıştır. Reynolds Ortalamalı Navier-Stokes hesaplamaları NUMECA International tarafından geliştirilmiş olan FINE/Turbo akış çözücüsü ile yapılmıştır. Edi viskozitesini hesaplamak için Spalart-Allmaras türbülans modeli kullanılmıştır. Referans pali olarak Caradonna-Tung rotor pali seçilmiştir. Referans pal ile aynı planform alana sahip olacak şekilde muhtelif kanat açıklığı konumlarında maksimum veter uzunluğunun girdi olarak verilmesi ile farklı pal şekilleri elde edilmiştir. Üç eniyi durum gözlenmiştir: maksimum verim ölçüsü, referans verim ölçüsünde maksimum itki, referans itkide maksimum verim ölçüsü. Bu üç eniyi durum, maksimum veter uzunluğunun referans veterin 1.3 katı olduğu koşulda görülmüştür.

Kaynakça

Giovanetti E.B. & Hall K.C., “Minimum Loss Load, Twist, and Chord Distributions for Coaxial Helicopters in Hover,” Journal of the American Helicopter Society, Vol. 62, 012001, 2017.

NUMECA International. “IGG/AutoGrid5 Software Package,” ver.11.2rc, User Manual, 2017.

NUMECA International, “FINE/Turbo Software Package,” ver.11.2rc, User Manual, 2017.

Caradonna F. X. & Tung C., “Experimental and Analytical Studies of a Model Helicopter Rotor in Hover,” Army Aeromechanics Laboratory’s hover test facility, NASA Technical Memorandum 81 232, 1981.

Elfarra M., Kaya M., & Kadioglu F., “A Parametric CFD Study for the Effect of Spanwise Parabolic Chord Distribution on the Thrust of an Untwisted Helicopter Rotor Blade,” 2018 AIAA Aerospace Sciences Meeting, 8–12 January 2018, Kissimmee, Florida, 2018.

Yucekayali A., Ezertas A. & Ortakaya Y., “Whirl Tower Testing and Hover Performance Evaluation of a 3 Meter Radius Rotor Design,” 7th Ankara International Aerospace Conference, 11-13 September 2013 - METU, Ankara Turkey, AIAC- 2013-142, 2013.

Mohd N.A.R.N. & Barakos G., “Computational Aerodynamics of Hovering Helicopter Rotors,” Jurnal Mekanikal, No 34, pp. 16-46, 2012.

Steijl R., Barakos G. & Badcock K., “A framework for CFD analysis of helicopter rotors in hover and forward flight,” Int. J. Numer. Meth. Fluids, Vol. 51, pp. 819–847, 2006.

Vua N.A. & Leeb J.W., “Aerodynamic design optimization of helicopter rotor blades including airfoil shape for forward flight,” Vol. 42, pp. 106–117, 2015.

Walsh J.L., Bingham G.J. & Riley M.F., “Optimization Methods Applied to the Aerodynamic Design of Helicopter Rotor Blades,” Journal of the American Helicopter Society, Vol. 32, No. 4, pp. 39- 44(6), 1987.

McVeigh M.A. & McHugh, F.J., “Influence of Tip Shape, Chord, Blade Number, and Airfoil on Advanced Rotor Performance,” Journal of the American Helicopter Society, Vol. 29, No. 4, 55- 62(8), 1984.

Choi S., Lee K., Potsdam, M.M. & Alonso J.J., “Helicopter Rotor Design Using a Time-Spectral and Adjoint-Based Method,” Journal Of Aircraft, Vol. 51(2), pp. 412-423, 2014.

Allen C.B. & Rendall T.C.S., “CFD-based optimization of hovering rotors using radial basis functions for shape parameterization and mesh deformation,” Optim Eng, Vol. 14, pp. 97–118, 2013.

Dumont A., Le Pape A., J. Peter & Huberson, S., “Aerodynamic Shape Optimization of Hovering Rotors Using a Discrete Adjoint of the Reynolds- Averaged Navier–Stokes Equations,” Journal Of The American Helicopter Society, Vol. 56, 032002, 2011.

Le Pape A. & Beaumier P., “Numerical optimization of helicopter rotor aerodynamic performance in hover,” Aerospace Science and Technology, Vol. 9, pp. 191–201, 2005.

Conlisk AT., “Modern helicopter aerodynamics,” Annual Review of Fluid Mechanics, Vol. 29, pp. 515 – 567, 1997.

Allen CB., “An unsteady multiblock multigrid scheme for lifting forward flight rotor simulation,” International Journal for Numerical Methods in Fluids, Vol. 45(9), pp. 943 –984, 2004.

Srinivasan GR & Baeder JD., “TURNS: a free- wake Euler–Navier–Stokes numerical method for helicopter,” AIAA Journal, Vol. 31(5), pp. 959 –962, 1993.

Chen CL, McCroskey WJ & Obayashi S., “Numerical solutions of forward-flight rotor flow using an upwind method,” Journal of Aircraft, Vol.28(6), pp. 374 –380, 1991.

Park Y. & Kwon O., “Simulation of unsteady rotor flowfield using unstructured adaptive sliding meshes,” Journal of the American Helicopter Society, Vol. 49(4), pp. 391– 400, 2004.

Servera G, Beaumier P & Costes M., “A weak coupling method between the dynamics code HOST and the 3D unsteady Euler code WAVES,” Aerospace Science and Technology, Vol. 5, pp. 397– 408, 2001.

Pomin H & Wagner S., “Navier–Stokes analysis of helicopter rotor aerodynamics in hover and forward flight,” Journal of Aircraft, Vol. 39(5), pp. 813–821, 2002.

Gecgel M., “Modeling and simulation of coaxial helicopter rotor aerodynamics,” PhD thesis, Old Dominion University, 2009.

Renzoni R, D’Alascio A, Kroll N, Peshkin D, Hounjet M, Boniface J-C, Vigevano L, Morino L, Allen CB, Badcock KJ, Mottura L, Scholl M & Kokkalis E., “A common European Euler code for the analysis of the helicopter rotor flowfield,” Progress in Aerospace Sciences, Vol. 36, pp. 437– 485, 2000.

Kaynak Göster