Impact of cyclostationarity on fan broadband noise prediction

Abstract One of the dominant noise sources of modern Ultra High Bypass Ratio (UHBR) engines is the interaction of the rotor wakes with the leading edges of the stator vanes in the fan stage. While the tonal components of this noise generation mechanism are fairly well understood by now, the broadband components are not. This calls to further the understanding of the broadband noise generation in the fan stage. This article introduces a new extension to the Random Particle Mesh (RPM) method, which accommodates in-depth studies of the impact of cyclostationary wake characteristics on the broadband noise in the fan stage. The RPM method is used to synthesize a turbulence field in the stator domain using a URANS simulation characterized by time-periodic turbulence and mean flow. The rotor-stator interaction noise is predicted by a two-dimensional CAA computation of the stator cascade. The impact of cyclostationarity is decomposed into various effects, which are separately investigated. This leads to the finding that the periodic turbulent kinetic energy (TKE) and periodic flow have only a negligible effect on the radiated sound power. The impact of the periodic integral length scale (TLS) is, however, substantial. The limits of a stationary representation of the TLS are demonstrated making this new extension to the RPM method indispensable when background and wake TKE are of comparable level. Good agreement of the predictions with measurements obtained from the 2015 AIAA Fan Broadband Noise Prediction Workshop are also shown.

[1]  Vincent P. Blandeau,et al.  Comparison of sound power radiation from isolated airfoils and cascades in a turbulent flow. , 2011, The Journal of the Acoustical Society of America.

[2]  C. Tam,et al.  RADIATION AND OUTFLOW BOUNDARY CONDITIONS FOR DIRECT COMPUTATION OF ACOUSTIC AND FLOW DISTURBANCES IN A NONUNIFORM MEAN FLOW , 1996 .

[3]  Phillip Joseph,et al.  Investigation of Rotor Wake Turbulence Through Cyclostationary Spectral Analysis , 2009 .

[4]  Roland Ewert,et al.  Sweeping Sound Generation in Jets Realized with a Random Particle-Mesh Method , 2009 .

[5]  Ivan Flaminio Cozza,et al.  Broadband Trailing Edge Noise Prediction with a Stochastic Source Model , 2012 .

[6]  Roland Ewert,et al.  Analytical reconstruction of isotropic turbulence spectra based on the Gaussian transform , 2016 .

[7]  Gabriel Reboul,et al.  Numerical Predictions of Turbulence/Cascade-Interaction Noise Using Computational Aeroacoustics with a Stochastic Model , 2015 .

[8]  Sebastien Guerin,et al.  Fan noise scaling of static data using semi-analytical methods and assessment against experimental data , 2015 .

[9]  Sébastien Candel,et al.  Stochastic approach to noise modeling for free turbulent flows , 1994 .

[10]  C. L. Morfey,et al.  Sound transmission and generation in ducts with flow , 1971 .

[11]  Alex S.H. Lau,et al.  The effect of wavy leading edges on aerofoil-gust interaction noise , 2013 .

[12]  Tsuyoshi Murata,et al.  {m , 1934, ACML.

[13]  F. Arnold.  Experimentelle und numerische Untersuchung zur Schalleistungsbestimmung in Strömungskanälen , 1999 .

[14]  G. Gabard,et al.  A CAA Study of Turbulence Distortion in Broadband Fan Interaction Noise , 2016 .

[15]  Roland Ewert,et al.  CAA broadband noise prediction for aeroacoustic design , 2011 .

[16]  Mark Allan,et al.  Comparison of LES and Stochastic Source Generation Methods for Aero- and Hydro-Acoustic Design Guidance , 2014 .

[17]  K. Carlson,et al.  Turbulent Flows , 2020, Finite Analytic Method in Flows and Heat Transfer.

[18]  Graham Ashcroft,et al.  Turbulence Treatment in Steady and Unsteady Turbomachinery Flows , 2010 .

[19]  Jae Wook Kim,et al.  An advanced synthetic eddy method for the computation of aerofoil-turbulence interaction noise , 2015, J. Comput. Phys..

[20]  Roland Ewert,et al.  Simultaneous Computation of Surface and Volume Sources for Fan Broadband Noise with the Random-Particle-Mesh Method , 2013 .

[21]  Axel Holewa,et al.  Impact of bypass-duct bifurcations on fan noise , 2014 .

[22]  Gary G. Podboy,et al.  Steady and Unsteady Flow Field Measurements Within a NASA 22-Inch Fan Model , 2002 .

[23]  M. Nallasamy,et al.  Computation of rotor wake turbulence noise , 2005 .

[24]  N. Peake,et al.  Influence of mean loading on noise generated by the interaction of gusts with a cascade: downstream radiation , 2004, Journal of Fluid Mechanics.

[25]  R. K. Amiet,et al.  High frequency thin-airfoil theory for subsonic flow , 1976 .

[26]  Wim Desmet,et al.  An overview of high-order finite difference schemes for computational aeroacoustics , 2004 .

[27]  Roland Ewert,et al.  Extension of the Random Particle Mesh method to periodic turbulent flows for fan broadband noise prediction , 2015 .

[28]  Antonio Napolitano,et al.  Cyclostationarity: Half a century of research , 2006, Signal Process..

[29]  R. Kraichnan.  Diffusion by a Random Velocity Field , 1970 .

[30]  William J. Devenport,et al.  Panel methods for airfoils in turbulent flow , 2010 .

[31]  M. Dieste,et al.  Random particle methods applied to broadband fan interaction noise , 2012, J. Comput. Phys..

[32]  R. Ewert.  Broadband slat noise prediction based on CAA and stochastic sound sources from a fast random particle-mesh (RPM) method , 2008 .

[33]  Gwenael Gabard,et al.  Broadband Fan Interaction Noise using Synthetic Inhomogeneous Non-stationary Turbulence , 2011 .

[34]  Roland Ewert,et al.  A three-parameter Langevin model for hot jet mixing noise prediction , 2012 .

[35]  Roland Ewert,et al.  Numerical Simulation of Aerodynamic Noise with DLR's aeroacoustic code PIANO , 2008 .

[36]  B. Coppotelli,et al.  Proceedings of the International Conference on Noise and Vibration Engineering , 2004 .

[37]  Hafiz M. Atassi,et al.  A finite difference, frequency-domain numerical scheme for the solution of the gust response problem , 1995 .

[38]  Kai Becker,et al.  Recent Progress In A Hybrid-Grid CFD Solver For Turbomachinery Flows , 2010 .

[39]  Phillip Joseph,et al.  Reduced Dimension Modeling of Leading Edge Turbulent Interaction Noise , 2014 .

[40]  Lucas J. van Vliet,et al.  Recursive implementation of the Gaussian filter , 1995, Signal Process..

[41]  Phillip Joseph,et al.  Experimental and numerical investigation of turbulence-airfoil noise reduction using wavy edges , 2013 .

[43]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[44]  R. Ewert,et al.  Linear- and Non-Linear Perturbation Equations with Relaxation Source Terms for Forced Eddy Simulation of Aeroacoustic Sound Generation , 2014 .

[45]  M.Y. Hussaini,et al.  Low-Dissipation and Low-Dispersion Runge-Kutta Schemes for Computational Acoustics , 1994 .

[46]  C. Tam,et al.  Dispersion-relation-preserving finite difference schemes for computational acoustics , 1993 .

[47]  F. Grimm,et al.  The Fast Random Particle Method for Combustion Noise Prediction , 2014 .