Radial flow effects on a retreating rotor blade

RADIAL FLOW EFFECTS ON A RETREATING ROTOR BLADE Report Title This work studies the effects of radial flow on the aerodynamic phenomena occurring on a retreating blade with a focus on dynamic stall and reverse flow as applied to a helicopter rotor in forward flight and a wind turbine operating at a yaw angle. While great progress has been made in understanding the phenomenon of two-dimensional dynamic stall, the effect of rotation on the dynamic stall event is not well understood. Experiments were conducted on a rigid two bladed teetering rotor at high advance ratios in a low speed wind tunnel. Particle image velocimetry (PIV) measurements were used to quantify the flow field at several azimuthal angles on the rotating blade during the dynamic stall event. The effect of predominant centrifugal forces induced radial velocity on the dynamic stall event was studied in detail. Further investigation of the radial flow field suggested that the mean radial velocity attenuated on moving outboard due to an apparent shear layer instability and it was demonstrated to be of first order importance in the flow field. These radial flow results prompted an exploration of the flow over a rotating disk to establish similarities of the radial flow over rotating blade in separated flow to that over a rotating disk in separated flow. While a greater part of this work focused on aspects of dynamic stall on the retreating blade, the final parts focus on the exotic flow regime of reverse flow (characterized by flow from the trailing edge to the leading edge of the blade). Aerodynamic loads measurement and surface flow visualization via tufts are used to first quantify the behavior of a static yawed blade in reverse flow. PIV measurements are then used on a static yawed blade and a rotating blade in reverse flow conditions to ascertain the effects of rotation on reverse flow. RADIAL FLOW EFFECTS ON A RETREATING ROTOR BLADE A Thesis Presented to The Academic Faculty

[1]  Hyeonsoo Yeo,et al.  Investigation of UH-60A Rotor Performance and Loads at High Advance Ratios , 2013 .

[2]  Scott Schreck,et al.  Blade Three-Dimensional Dynamic Stall Response to Wind Turbine Operating Condition , 2005 .

[3]  William G. Bousman,et al.  Evaluation of Airfoil Dynamic Stall Characteristics for Maneuverability , 2001 .

[4]  Steen Krenk,et al.  Dynamic Stall Model for Wind Turbine Airfoils , 2007 .

[5]  R. Adrian,et al.  Stereoscopic particle image velocimetry applied to liquid flows , 1993 .

[6]  Cellular Structures in the Flow Over the Flap of a Two-Element Wing , 1998 .

[7]  W. Mccroskey,et al.  Analysis of the development of dynamic stall based on oscillating airfoil experiments , 1977 .

[8]  F. Scarano,et al.  Visualization by PIV of dynamic stall on a vertical axis wind turbine , 2009 .

[9]  Y. Kohama,et al.  Boundary-layer transition and the behaviour of spiral vortices on rotating spheres , 1983, Journal of Fluid Mechanics.

[10]  W. Mccroskey,et al.  Dynamic Stall Experiments on Oscillating Airfoils , 1975 .

[11]  L. Sirovich.  Turbulence and the dynamics of coherent structures. II. Symmetries and transformations , 1987 .

[12]  M. R. Malik,et al.  Instability and transition in rotating disk flow , 1981 .

[13]  H. Bijl,et al.  Simulating Dynamic Stall in a 2D VAWT: Modeling strategy, verification and validation with Particle Image Velocimetry data , 2007 .

[14]  K. Mulleners,et al.  The onset of dynamic stall revisited , 2012 .

[15]  R. Kobayashi,et al.  Boundary-layer transition on a rotating cone in still fluid , 1983, Journal of Fluid Mechanics.

[16]  M. S. Chandrasekhara,et al.  Quantitative study of unsteady compressible flow on an oscillating airfoil , 1994 .

[17]  A. Prasad.  Particle image velocimetry , 2000 .

[18]  W. J. Mccroskey,et al.  An Experimental Study of Dynamic Stall on Advanced Airfoil Sections. Volume 1. Summary of the Experiment. , 1982 .

[19]  F. B. Gustafson,et al.  Observations in Flight of the Region of Stalled Flow over the Blades of an Autogiro Rotor , 1939 .

[21]  Markus Raffel,et al.  Dynamic stall on a fully equipped helicopter model , 2012 .

[22]  Markus Raffel,et al.  Particle Image Velocimetry: A Practical Guide , 2002 .

[23]  Andy P. Broeren,et al.  Spanwise variation in the unsteady stalling flowfields of two-dimensional airfoil models , 2001 .

[24]  William G. Bousman,et al.  A Qualitative Examination of Dynamic Stall from Flight Test Data , 1997 .

[25]  Narayanan Komerath,et al.  Discrete Structures in the Radial Flow Over a Rotor Blade in Dynamic Stall , 2008 .

[26]  Narayanan Komerath,et al.  An Exploration of Radial Flow on a Rotating Blade in Retreating Blade Stall , 2013 .

[27]  R. Lingwood,et al.  An experimental study of absolute instability of the rotating-disk boundary-layer flow , 1996, Journal of Fluid Mechanics.

[28]  Frank N. Coton,et al.  An examination of key aerodynamic modelling issues raised by the NREL blind comparison , 2002 .

[29]  T. Kármán.  Über laminare und turbulente Reibung , 1921 .

[30]  F. Carta.  A comparison of the pitching and plunging response of an oscillating airfoil , 1979 .

[31]  W. H. H. Banks,et al.  DELAYING EFFECT OF ROTATION ON LAMINAR SEPARATION , 1963 .

[32]  R. Cucitore,et al.  On the effectiveness and limitations of local criteria for the identification of a vortex , 1999 .

[33]  Jürgen Kompenhans,et al.  Demonstration by PIV of the Non-Reproducibility of the Flow Field Around an Airfoil Pitching Under Deep Dynamic Stall Conditions and Consequences Thereof , 1997 .

[34]  Thomas R. Norman,et al.  Experimental Investigation and Fundamental Understanding of a Full-Scale Slowed Rotor at High Advance Ratios , 2013 .

[35]  Eastman N. Jacobs,et al.  Airfoil section characteristics as affected by variations of the Reynolds number , 1939 .

[36]  M. Raffel,et al.  Investigation of the unsteady flow velocity field above an airfoil pitching under deep dynamic stall conditions , 1995 .

[37]  Mc Croskey.  Measurements of boundary layer transition, separation and streamline direction on rotating blades , 1971 .

[38]  Michael Robinson,et al.  Horizontal Axis Wind Turbine Aerodynamics: Three-Dimensional, Unsteady, and Separated Flow Influences , 1999 .

[39]  W. Cochran.  The flow due to a rotating disc , 1934, Mathematical Proceedings of the Cambridge Philosophical Society.

[40]  W. Mccroskey,et al.  An Experimental Study of Dynamic Stall on Advanced Airfoil Sections. Volume 2. Pressure and Force Data. , 1982 .

[41]  Y. Kohama,et al.  Spiral vortices in boundary layer transition regime on a rotating disk , 1980 .

[42]  M. S. Chandrasekhara,et al.  Design and development of a compressible dynamic stall facility , 1992 .

[43]  J. Barlow,et al.  Flowfield Model for a Rectangular Planform Wing beyond Stall , 1980 .

[44]  L. Carr.  Progress in analysis and prediction of dynamic stall , 1988 .

[45]  K. Pengel,et al.  Recording and evaluation methods of PIV investigations on a helicopter rotor model , 2004 .

[46]  Franklin D. Harris,et al.  Rotor Performance at High Advance Ratio: Theory versus Test , 2008 .

[47]  Ken Badcock,et al.  Investigation of Three-Dimensional Dynamic Stall Using Computational Fluid Dynamics , 2005 .

[48]  Patrick Ormande Bowles,et al.  Wind Tunnel Experiments on the Effect of Compressibility on the Attributes of Dynamic Stall , 2012 .

[49]  N. Fujisawa,et al.  Flow visualization and PIV measurement of flow field around a darrieus rotor in dynamic stall , 1998 .

[50]  M. S. Chandrasekhara,et al.  Reattachment studies of an oscillating airfoil dynamic stall flowfield , 1994 .

[51]  J. C. Biggers,et al.  An investigation of full-scale helicopter rotors at high advance ratios and advancing tip Mach numbers , 1968 .

[52]  Jaan Liiva,et al.  Dynamic Stall Of Airfoil Sections For High-Speed Rotors , 1969 .

[53]  Yasuaki Kohama,et al.  Some expectation on the mechanism of cross-flow instability in a swept wing flow , 1987 .

[54]  L. Carr,et al.  Compressibility effects on dynamic stall , 1996 .

[55]  Tillmann A. Friederich,et al.  Numerical investigation of rotational augmentation for S822 wind turbine airfoil , 2012 .

[56]  M. C. Robinson,et al.  Evidence that aerodynamic effects, including dynamic stall, dictate HAWT structural loads and power generation in highly transient time frames , 1994 .

[57]  Wei Shyy,et al.  Shallow and deep dynamic stall for flapping low Reynolds number airfoils , 2009 .

[58]  R. A. McD. Galbraith,et al.  Dynamic recovery to fully attached aerofoil flow from deep stall , 1995 .

[59]  D. Telionis,et al.  Boundary-layer separation in unsteady flow , 1975 .

[60]  S. F. Shen,et al.  The Genesis of Separation , 1982 .

[61]  R. Adrian.  Twenty years of particle image velocimetry , 2005 .

[62]  Bruce D. Charles,et al.  WIND TUNNEL INVESTIGATION OF SEMIRIGID FULL-SCALE ROTORS OPERATING AT HIGH ADVANCE RATIOS , 1969 .

[63]  M. Meunier.  Simulation and Optimization of Flow Control Strategies for Novel High-Lift Configurations , 2009 .

[64]  J. Gordon Leishman,et al.  Principles of Helicopter Aerodynamics , 2000 .

[65]  P. Holmes,et al.  The Proper Orthogonal Decomposition in the Analysis of Turbulent Flows , 1993 .

[66]  E. Jumper,et al.  The Effect of Pitch Location on Dynamic Stall , 1989 .

[67]  N. D. Ham,et al.  Torsional oscillation of helicopter blades due to stall. , 1966 .

[68]  P. F. Lorber.  Dynamic Stall of a Sinusoidally Oscillating Three-Dimensional Swept and Unswept Wing in Compressible Flow , 1992 .

[69]  Nobuyuki Fujisawa,et al.  Observations of dynamic stall on Darrieus wind turbine blades , 2001 .

[70]  John B Wheatley,et al.  Full-Scale Wind-Tunnel Tests of a PCA-2 Autogiro Rotor , 1935 .

[71]  P. Fraunié,et al.  Water channel experiments of dynamic stall on Darrieus wind turbine blades , 1986 .

[72]  Thomas Millott,et al.  High Airspeed Testing of the Sikorsky X2 Technology (TM) Demonstrator , 2011 .

[73]  Mark Potsdam,et al.  Computational Investigation and Fundamental Understanding of a Slowed UH-60A Rotor at High Advance Ratios , 2016 .

[74]  W. J. Mccroskey,et al.  Dynamic Stall on Advanced Airfoil Sections , 1981 .

[75]  R Katzmayr,et al.  Effect of Periodic Changes of Angle of Attack on Behavior of Airfoils , 1922 .

[76]  Narayanan Komerath,et al.  Radial Flow Measurements Downstream of Forced Dynamic Separation on a Rotor Blade , 2006 .

[77]  David Simms,et al.  Unsteady aerodynamics associated with a horizontal-axis wind turbine , 1996 .

[78]  Wolfgang Geissler,et al.  Investigation of dynamic stall onset , 2006 .

[79]  R. L. Halfman,et al.  Evaluation of high-angle attack aerodynamic-derivative data and stall-flutter prediction techniques , 1951 .

[80]  J. Katz,et al.  Cellular patterns in poststall flow over unswept wings , 1983 .

[81]  F. A. Varley.  Effects of Impeller Design and Surface Roughness on the Performance of Centrifugal Pumps , 1961 .

[82]  R. Adrian.  Particle-Imaging Techniques for Experimental Fluid Mechanics , 1991 .

[83]  Anthony Donald Gardner,et al.  Influence of rotation on dynamic stall , 2013 .

[84]  Max F. Platzer,et al.  Computational prediction of airfoil dynamic stall , 1998 .

[85]  George Haller,et al.  Exact theory of unsteady separation for two-dimensional flows , 2004, Journal of Fluid Mechanics.

[86]  C. P. Butterfield,et al.  Dynamic stall on wind turbine blades , 1991 .

[87]  Maureen Hand,et al.  HAWT dynamic stall response asymmetries under yawed flow conditions , 2000 .

[88]  N. Gregory,et al.  On the stability of three-dimensional boundary layers with application to the flow due to a rotating disk , 1955, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[89]  L. Graftieaux,et al.  Combining PIV, POD and vortex identification algorithms for the study of unsteady turbulent swirling flows , 2001 .

[90]  P. F. Yaggy,et al.  Laminar boundary layers on helicopter rotors in forward flight. , 1968 .

[91]  Nicholas J. Lawson,et al.  Three-dimensional particle image velocimetry: experimental error analysis of a digital angular stereoscopic system , 1997 .

[92]  Westland Helicopters,et al.  The Aerodynamics of the Helicopter World Speed Record , 1987 .

[93]  Norman D. Ham,et al.  Dynamic Stall Considerations in Helicopter Rotors , 1968 .

[94]  Jinhee Jeong,et al.  On the identification of a vortex , 1995, Journal of Fluid Mechanics.

[95]  W. J. McCroskey,et al.  Detailed aerodynamic measurements on a model rotor in the blade stall regime , 1971 .

[96]  A. T. Conlisk,et al.  MODERN HELICOPTER AERODYNAMICS , 1997 .

[97]  George Haller,et al.  An exact theory of three-dimensional fixed separation in unsteady flows , 2008 .

[98]  G. P. Corten.  Flow separation on wind turbines blades , 2001 .

[99]  W. H. Wentz,et al.  Vortex breakdown on slender sharp-edged wings , 1969 .

[100]  M. S. Chandrasekhara,et al.  Interferometric investigations of compressible dynamic stall over a transiently pitching airfoil , 1994 .

[101]  C P Butterfield.  Aerodynamic pressure and flow-visualization measurement from a rotating wind turbine blade , 1988 .

[102]  Max Kramer.  Increase in the maximum lift of an airplane wing due to a sudden increase in its effective angle of attack resulting from a gust , 1932 .