Accession Number : ADA266542


Title :   Hoph Bifurcation in Viscous, Low Speed Flows About an Airfoil with Structural Coupling


Descriptive Note : Doctoral thesis


Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING


Personal Author(s) : Lutton, Mark J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a266542.pdf


Report Date : Mar 1993


Pagination or Media Count : 152


Abstract : The locations of Hopf bifurcation points associated with the viscous, incompressible flow about a NACA 0012 airfoil with structural coupling are computed for very low Reynolds numbers (2000). A semi-implicit, first-order- accurate time-integration algorithm is employed to solve the stream-function- vorticity form of the Navier-Stokes equations. The formulation models the inclusion of simple structural elements affixed to the airfoil and captures the resulting airfoil motion. The equations describing the airfoil motion are integrated in time using a fourth-order Runge-Kutta algorithm. The dissertation is divided into two parts. In part one, numerical experiments are performed in the laminar regime to determine if the structural model of the airfoil has an effect upon the location of the Hopf bifurcation point when compared with the fixed airfoil. Results are reported for a variety of structural characteristics, including variations of torsional and linear spring constants, inertial properties, structural coupling, and structural damping. The structure of the solution space is explored by means of phase plots. In part two, the Baldwin- Lomax turbulence model is implemented to model turbulent flow. A numerical effort is made to predict the onset of unsteady flow.


Descriptors :   *COMPUTATIONAL FLUID DYNAMICS , *AIRFOILS , *VISCOUS FLOW , *AERODYNAMICS , ALGORITHMS , MODELS , DAMPING , MOTION , INCLUSIONS , FLOW RATE , UNSTEADY FLOW , FLUID FLOW , FLUTTER , FOURIER ANALYSIS , INCOMPRESSIBLE FLOW , REYNOLDS NUMBER , BIFURCATION(MATHEMATICS) , INVISCID FLOW , NAVIER STOKES EQUATIONS , FLUID DYNAMICS , COUPLINGS , WAKE , COMPRESSIBLE FLOW , VARIATIONS , THESES , TURBULENCE , TURBULENT FLOW , VORTICES


Subject Categories : Aerodynamics


Distribution Statement : APPROVED FOR PUBLIC RELEASE