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Cfd Investigation Of Effect Of Depth To Diameter Ratio On Dimple Flow // Computational Fluid Dynamics Investigation Of Effect Of Depth To Diameter Ratio On Dimple Flow Dynamics, Robert B. Etter
Theses and Dissertations
This study aimed to further the understanding of laminar flow through a dimple with the goal of mitigating flow separation. Dimples of various depth to diameter ratios (0.05, 0.15) were examined for three different dimple diameters and chordwise locations, corresponding to diameter based (ReD) and chordwise location based (Rex) Reynolds number combinations of ReD 20500\Rex 5000, ReD 20500 Rex 77000, and ReD 9000 Rex 21000. For the last combination, a dimple of depth to diameter ratio of 0.25 was also examined. The dimples were placed in a flat plate located in a diverging channel causing an adverse pressure gradient encouraging …
Use Of Dimples To Suppress Boundary Layer Separation On A Low Pressure Turbine Blade, Kurt P. Rouser
Use Of Dimples To Suppress Boundary Layer Separation On A Low Pressure Turbine Blade, Kurt P. Rouser
Theses and Dissertations
Flow separation on a low pressure turbine blade is explored at Reynolds numbers of 25k, 45k and 100k. Experimental data is collected in a low-speed, draw-down wind tunnel using a cascade of eight Pak-B blades. Flow is examined from measurements of blade surface pressures, boundary layer parameters, exit velocities, and total pressure losses across the blade. Two recessed dimple shapes are assessed for suppressing flow separation and associated losses. One dimple is spherical, and the second is asymmetric, formed from a full dimple spanwise half-filled. A single row of each dimple shape is tested at 50%, 55% and 65% axial …
Numerical Simulation Of Dynamic-Stall Suppression By Tangential Blowing, Matthew C. Towne
Numerical Simulation Of Dynamic-Stall Suppression By Tangential Blowing, Matthew C. Towne
Theses and Dissertations
The use of tangential blowing to suppress the dynamic stall of a pitching airfoil is investigated numerically. The laminar two-dimensional, compressible Navier-Stokes equations are solved time-accurately using a Beam- Warming algorithm. A slot is located at four different positions along the surface of a NACA 0015 airfoil and air is injected in a nearly tangential sense along the upper surface. Suction control is also employed at one of these slot locations to directly compare with tangential-blowing control. Solution sensitivity to grid refinement, time-step size, numerical smoothing, and initial conditions is investigated at a Reynolds number of 2.4 x 10exp 4. …
A Comparison Of Computational And Experimental Data For A Subscale High Speed Propulsive Nozzle At Low Mach Numbers, Yonghee Hyun
A Comparison Of Computational And Experimental Data For A Subscale High Speed Propulsive Nozzle At Low Mach Numbers, Yonghee Hyun
Theses and Dissertations
This computational study of a hypersonic sub-scale nozzle/cowl configuration compares numerical solutions with experimental data for nozzle performance at off design conditions (subsonic through supersonic Mach numbers. A combination of Van Leer and Roe flux-splitting algorithms was used to solve the flow field. The explicit formulation assumed laminar planar flow and the perfect gas equation of state. A validation for the numerical algorithm was accomplished by comparing with experimental data for a variety of cases. Grid refinement, geometry, and operating conditions all influenced the comparison of the experimental and computational data. Generally, as the Mach number and nozzle pressure ratio …
Hoph Bifurcation In Viscous, Low Speed Flows About An Airfoil With Structural Coupling, Mark J. Lutton
Hoph Bifurcation In Viscous, Low Speed Flows About An Airfoil With Structural Coupling, Mark J. Lutton
Theses and Dissertations
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.