Aerodynamic Noise Computation of the Flow Field around NACA 0012 Airfoil Using Large Eddy Simulation and Acoustic Analogy

Document Type : Research Paper

Authors

Department of Mechanical Engineering, University of Tehran, Tehran, Iran

Abstract

The current study presents the results of the aerodynamic noise prediction of the flow field around a NACA 0012 airfoil at a chord-based Reynolds number of 100,000 and at 8.4 degree angle of attack. An incompressible Large Eddy Simulation (LES) turbulence model is applied to obtain the instantaneous turbulent flow field. The noise prediction is performed by the Ffowcs Williams and Hawkings (FW-H) acoustic analogy. Both mean flow quantities and fluctuation statistics are studied. The behaviour of the turbulent vortical structures in the flow field from the perspective of the turbulent boundary layer development is visualized. Power spectral density of the lift coefficient is presented. The computed non-dimensional mean velocity profiles in the boundary layer compared reasonably well with the theoretical predictions. The boundary layer transition from a laminar state to a turbulent state is also brought into focus. The skin friction coefficient and the urms streamwise velocity fluctuations predicted a transition zone from x/c=0.23 to x/c=0.45. Then, the research focuses on the broadband noises of the turbulent boundary layers and the tonal noises that arise from the vortex shedding generated by the laminar boundary layers. The spectra computed from the acoustic pressure are compared with the experimental data. The effect of observer location on the overall sound pressure level (OASPL) is investigated and the results indicate that the OASPL varies logarithmically with the receiver distance, as was expected.

Keywords

Main Subjects

[1]. Jianu, O., Rosen, M. A., and Naterer, G., 2012, "Noise Pollution Prevention in Wind Turbines: Status and Recent Advances," Sustainability, 4(6): 1104-1117.
[2]. Pedersen, E., and Waye, K. P., 2007, "Wind turbine noise, annoyance and self-reported health and well-being in different living environments," Occupational and environmental medicine, 64(7): 480-486.
[3]. Wagner, S., Bareiss, R., Guidati, G., and Wagner-Bareiß-Guidati, 1996, "Wind turbine noise."
[4]. Oerlemans, S., Sijtsma, P., and Méndez López, B., 2007, "Location and quantification of noise sources on a wind turbine," Journal of sound and vibration, 299(4): 869-883.
[5]. Brooks, T. F., Pope, D. S., and Marcolini, M. A., 1989, Airfoil self-noise and prediction, National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division.
[6]. Wang, M., and Moin, P., 2000, "Computation of trailing-edge flow and noise using large-eddy simulation," AIAA journal, 38(12): 2201-2209.
[7]. Williams, J., and Hall, L., 1970, "Aerodynamic sound generation by turbulent flow in the vicinity of a scattering half plane," Journal of Fluid Mechanics, 40(04): 657-670.
[8]. Singer, B. A., Brentner, K. S., Lockard, D. P., and Lilley, G. M., 2000, "Simulation of acoustic scattering from a trailing edge," Journal of Sound and Vibration, 230(3): 541-560.
[9]. Shen, W. Z., Zhu, W., and Sørensen, J. N., 2009, "Aeroacoustic computations for turbulent airfoil flows," AIAA journal, 47(6): 1518-1527.
[10]. Jones, L. E., Sandham, N. D., and Sandberg, R. D., 2010, "Acoustic source identification for transitional airfoil flows using cross correlations," AIAA journal, 48(10): 2299-2312.
[11]. Kim, T., Lee, S., Kim, H., and Lee, S., 2010, "Design of low noise airfoil with high aerodynamic performance for use on small wind turbines," Science in China Series E: Technological Sciences, 53(1): 75-79.
[12]. Göçmen, T., and Özerdem, B., 2012, "Airfoil optimization for noise emission problem and aerodynamic performance criterion on small scale wind turbines," Energy, 46(1): 62-71.
[13]. Wolf, W. R., and Lele, S. K., 2012, "Trailing-Edge Noise Predictions Using Compressible Large-Eddy Simulation and Acoustic Analogy," AIAA journal, 50(11): 2423-2434.
[14]. Lilly, D. K., 1992, "A proposed modification of the Germano subgrid‐scale closure method," Physics of Fluids A: Fluid Dynamics (1989-1993), 4(3): 633-635.
[15]. Williams, J. F., and Hawkings, D. L., 1969, "Sound generation by turbulence and surfaces in arbitrary motion," Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 264(1151): 321-342.
[16]. Lighthill, M. J., 1952, "On sound generated aerodynamically. I. General theory," Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 211(1107): 564-587.
[17]. Di Francescantonio, P., 1997, "A new boundary integral formulation for the prediction of sound radiation," Journal of Sound and Vibration, 202(4): 491-509.
[18]. Morris, P. J., Long, L. N., and Brentner, K. S., "An aeroacoustic analysis of wind turbines," Proc. 23rd ASME Wind Energy Symposium, AIAA Paper: 5-8.
[19]. Farassat, F., and Succi, G. P., "The prediction of helicopter rotor discrete frequency noise," Proc. In: American Helicopter Society, Annual Forum, 38th, Anaheim, CA, May 4-7, 1982, Proceedings.(A82-40505 20-01) Washington, DC, American Helicopter Society, 1982: 497-507.
[20]. Sheldahl, R. E., and Klimas, P. C., 1981, "Aerodynamic characteristics of seven symmetrical airfoil sections through 180-degree angle of attack for use in aerodynamic analysis of vertical axis wind turbines," Sandia National Labs., Albuquerque, NM (USA).
[21]. Afzal, N., "Wake layer in a turbulent boundary layer with pressure gradient- A new approach," Proc. IUTAM Symposium on Asymptotic Methods for Turbulent Shear Flows at High Reynolds Numbers, Bochum, Germany: 95-118.
[22]. Marsden, O., Bogey, C., and Bailly, C., 2008, "Direct noise computation of the turbulent flow around a zero-incidence airfoil," AIAA journal, 46(4): 874-883.
[23]. Hoffmann, J. A., Kassir, S., and Larwood, S., 1989, "The influence of free-stream turbulence on turbulent boundary layers with mild adverse pressure gradients."
[24]. Hunt, J. C., Wray, A., and Moin, P., "Eddies, streams, and convergence zones in turbulent flows," Proc. Studying Turbulence Using Numerical Simulation Databases, 2: 193-208.
[25]. Chakraborty, P., Balachandar, S., and Adrian, R. J., 2005, "On the relationships between local vortex identification schemes," Journal of Fluid Mechanics, 535: 189-214.
[26]. Kato, C., Iida, A., Takano, Y., Fujita, H., and Ikegawa, M., 1993, "Numerical prediction of aerodynamic noise radiated from low mach number turbulent wake," AIAA paper(93-0145).
Volume 46, Issue 1 - Serial Number 1
Winter & Spring
January 2015
Pages 41-50
  • Receive Date: 10 January 2015
  • Revise Date: 28 January 2015
  • Accept Date: 25 February 2015