• Nik Ahmad Ridhwan Nik Mohd Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia
  • George N. Barakos 2CFD Laboratory, University of Liverpool, Liverpool, L69 3GH, UK


CFD, hovering, rotor wake, RANS, source-sink, vortex-tube


The computation of rotor flowfields is a challenging problem in theoretical aerodynamics and essential for rotor design. In this paper we discuss the prediction of rotor hover performance, wake geometry and its strength using CFD methods. The benefits and differences between simple, momentum-based source-sink models and truncated vortextube far-field boundary conditions on the rotor flowfield modelling, and the convergence of the numerical solution are investigated and presented. Helicopter rotors in axial flight are simulated using the Helicopter Multi-block (HMB2) solver of the Liverpool University for a range of rotor tip speeds and collective pitch settings. The predicted data were then compared with available experimental data and the results indicates that, blade loading and wake geometry are in excellent agreement with experiments and have moderate sensitivity to the grid resolution. The work suggests that efficient solutions can be obtained and the use of the momentum theory is essential for efficient CFD computations.


Dietz, M., Kebler, M., Kramer, E., and Wagner, S., “Tip Vortex Conservation on a Helicopter Main Rotor Using Vortex- Adapted Chimera Grids,†AIAA Journal , Vol. 45, No. 8, 2007, pp. 2062–2974.

Strawn, R. G. and Djomehri, M. J., “Computational Modelling of Hovering rotor and Wake Aerodynamics,†Journal of Aircraft , Vol. 39, No. 5, 2002, pp. 786–793.

Hariharan, N. and Sankar, L. N., “A Review of Computational Technique or Rotor Wake Modeling,†AIAA–00–0114.

Boelens, O. J., van der Ven, H., Oskam, B., and Hassan, A. A., “Accurate and Efficient Vortex-Capturing for Rotor Blade Vortex Interaction,†NLR-TP-2000-051, 2000.

Zhao, J. and He, C., “A Viscous Vortex Particle Model for Rotor Wake and Interference Analysis,†American Helicopter Society, 64th Annual , 2008.

Zhao, Q. J., Xu, G. H., and Zhao, G. J., “New Hybrid Method for Predicting the Flowfields of Helicopter Rotors,†Journal of Aircraft , Vol. 43, 2006, pp. 372–380.

Anusonti-Inthra, P. and Floros, M., “Coupled CFD and Particle Vortex Transport

Method: Wing Performance and Wake Validations,†38th Fluid Dynamics Conference and Exhibition, AIAA 2008-4177, 2008.

Srinivasan, G. R., “A Free-Wake Euler and Navier-Stokes CFD Method and Its Application to Helicopter Rotors Including Dynamic Stall,†JAI Associate, Inc 93-01, Nov. 1993.

Wang, S. C., “Analytical Approach to the Induced Flow of a Helicopter Rotor in Vertical Descent,†Journal of the American Helicopter Society, Vol. 35, 1990, pp. 382–397.

Choi, W., Lee, S., Jung, J., and Lee, S., “New Far-Field Boundary and Initial Condition for Computation of Rotors in Vertical Flight Using Vortex Tube Model,†Journal of the American Helicopter Society, Vol. 43, 2008, pp. 382–397.

Perry, F. J., Chan, W. F. Y., Simon, I., Brown, R. E., Ahlin, G. A., Khelifa, B. M., and Newman, S. M., “Modelling the Mean Flow through a Rotor in Axial Flight Including Vortex Ring Conditions,†Journal of the American Helicopter Society, Vol. 52, 2007, pp. 224–238

Caradonna, F. X. and Tung, C., “Experimental and Analytical Studies of a Model Helicopter Rotor in Hover,†1981.

Tung, C., Pucci, S. L., Caradonna, F. X., and Morse, H. A., “The Structure of Trailing Vortices Generated by Model Rotor Blades,†Nasa tm 81316, 1981.

Ramasamy, M., Johnson, B., Huismann, T., and Leishman, J. G., “Procedures for Measuring the Turbulence Character- istics of Rotor Blades Tip Vortices,†Journal of the American Helicopter Society, Vol. 54, 2009, pp. 1–17.

Caradonna, F. X., “Performance Measurement and Wake Characteristics of a Model Rotor in Axial Flight,†Journal of the American Helicopter Society, 1999, pp. 101–108.

Steijl, R., Barakos, G., and Badcock, K., “A Framework for CFD Analysis of Helicopter Rotors in Hover and Forward Flight,†International Journal for Numerical Methods in Fluids, Vol. 51, 2006, pp. 819–828. doi: 10.1002/fld.1086.

Brocklehurst, A., Steijl, R., and Barakos, G., “CFD for Tail Rotor Design and Evaluation,†34th European Rotorcraft Forum, 2008.

Choi, W., Lee, S., Jung, J., and Lee, S., “Numerical Prediction of Hovering Rotor Tip Vortex using Vortex Tube Model Boundary Condition,†The European Rotorcraft Forum, 2007.

Castles, W. J. and Gray, R. B., “Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors,†NACA TN 2474, 1951.

Badcock, K. J., Richard, B. E., and Woodgate, M. A., “Elements of Computational Fluid Dynamics on Block Structured Grids using Implicit Solvers,†Progress in Aerospace Sciences, Vol. 36, 2000, pp. 355–364.

Wilcox, D. C., “Reassessment of the Scale Determining Equation for Advanced Turbulence Models,†AIAA Journal , Vol. 25, 1988, pp. 1299–1310.

Gagliardi, A. and Barakos, G. N., “Improving Hover Performance of Low-Twist Rotors using Trailing-Edge Flaps - A Computational study,†34th European Rotorcraft Forum, 2008.

Johnson, W., Helicopter Theory, Princeton University Press, 1980.

Vatistas, G. H., Kozel, V., and Mih, W. C., “A Simpler Model for Concentrated Vortices,†Experiment in Fluids, Vol. 11,No. 1, 1991, pp. 73–76.

Leishman, J. G., Principles of Helicopter Aerodynamics, Cambridge University press, 2006.




How to Cite

Nik Mohd, N. A. R., & Barakos, G. N. (2018). COMPUTATIONALAERODYNAMICS OF HOVERING HELICOPTER ROTORS. Jurnal Mekanikal, 34(1). Retrieved from