Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 42 for “"Strouhal number"”.
-
Maneuvering of a robotic pike
… are quantified and analyzed. A non-dimensional number, the Maneuvering Strouhal Number (Stm) is defined based on observations from live fish and previous theoretical developments. Recommendations for further improvements in the maneuvering performance of flexible hull vehicles are derived based …
-
Blade tonal noise reduction using tail articulation at high Reynolds number
… freestream velocities corresponding to Reynolds number in the range 75,000 < Re < 300,000 and (ii) operate at frequencies up to 30 Hz in order to investigate the range of Strouhal number 0.0 < St < 0.35. Velocity measurements in the active stator wake are carried out by Laser Doppler Velocimetry, …
-
Performance of biologically inspired flapping foils
… fashion. The effects of varying Reynolds number, Strouhal number, maximum pitch angle, and the phase shift between heave and pitch were studied. It was determined that at very low Strouhal numbers the wake was 'S' like and at moderate Strouhal numbers the wake contained discreet …
-
Reduction of unsteady underwater propeller forces via active tail articulation
… stator model. Tests were conducted at a Reynolds number of 75,000 and stator tail articulation was carried out in the range of Strouhal number 0.0 < St < 0.13. A variety of non-lifting propellers were used to investigate sinusoidal articulation profiles in the range of am- plitudes (2°,5°,10°), …
-
The Influence of Trailing Edge Shape and Kinematics on Bio-inspired Pitching Panels
… in a systematic manner at moderate Reynolds number. The wakes behaviors and wake dynamics of these panels are explored in a time-varying and time-averaged sense using results obtained from multiple planes of stereoscopic particle image velocimetry. The time-averaged and time-varying …
-
Unsteady modes in the flowfield about an airfoil with a leading-edge horn-ice shape
… shedding from the separation bubble. The average Strouhal number of this regular mode corresponded to StL = 0.60, and the average vortex convection velocity was observed to be 0.45U∞. These values were highly consistent with those reported elsewhere in the literature. The other two frequencies …
-
Three-dimensional vortical structures in the wake of a flexible flapping foil
… of a flexible flapping foil at Reynolds number 164. Flexible foils were fabricated, coated with fluorescent dye, and towed with heave and pitch in a large glass tank. The foil cross section is a NACA 0030 foil shape, and the foil has an aspect ratio of 3. Pictures where taken of the …
-
Study of Steady and Pulsating Impinging Jets
… diameters in length.The effects of the Reynolds number, the nozzle-to-plate spacing and the Strouhal number were investigated systematically. The range of the Reynolds numbers covered is 4000 to 10000 for the steady jets, and 4200 to 10240 for the pulsed jets. The nozzle-to-plate spacings …
-
Study of flow past elliptic and circular cylinders using direct numerical simulation
… it is found that important quantities like the Strouhal number and lift and drag coefficients match well with established values.
-
Etude expérimentale des sons auto-entretenus produits par un jet issu d'un conduit et heurtant une plaque fendue
… tones (up to 125 dB) by a low Mach number free plane jet impinging on a slotted plate, known as slot-tone, is experimentally studied. For all geometries of the slot’s edge tested, the tones are generated from 6 m/s and when a resonant mode of the duct from which the jet flows out is …
-
Structure and Dynamics of a Reacting Jet Injected into a Vitiated Crossflow in a Staged Combustion System
… with the reacting jet in crossflow. The wake Strouhal number calculation provides a better physical insight into the influence of jet velocity profile and nature of crossflow. A decrease in wake Strouhal number is noticed with an increase in nozzle separation distance. The effect of near-field …
-
Assessment of Formulations for Numerical Solutions of Low Speed, Unsteady, Turbulent Flows over Bluff Bodies
… aerodynamic forces, mean pressure coefficient, Strouhal number, mean velocity magnitude and turbulence intensity. The main results can be summarized as follows. First, the predictions are more sensitive to the turbulence model choice than to the choice of algorithm. The Spalart-Allmaras model …
-
Nonlinear electrokinetic transport and its applications under combined AC and DC fields in micro/nanofluidic interface devices
… greater than the DC voltage and at low Strouhal number, results in large dual concentration polarization regions (with unequal lengths) at both the micro/nanofluidic interfaces due to large and unequal voltage drops at these junctions. The highly nonlinear potential distribution gives …
-
Dynamical systems analysis of electrostatic and aerodynamic forced vibrations of a thin flexible electrode
… 0.224 - 3.58 m/s (0.5 - 8 mile/hr). The Reynolds numbers for these speeds lie in the range of 1000 - 20000. A range of control parameters leading to stable vibrations are established using the Strouhal number as the operating parameter whose inverse values change from 100 - 2500. The Numerical …
-
Investigating the Effect of an Upstream Spheroid on Tandem Hydrofoils
… data. The simulations were run for a range of Strouhal numbers (0.2-0.5) and phase differences (0-π). Results were compared to identical simulations without an upstream body to determine how the body affects thrust generation and the unsteady flow field.</p> <p>The combined time-averaged thrust …
-
Large eddy simulation of acoustic propagation in turbulent flow through ducts and mufflers
… solver is developed and validated for a low Mach number flow simulation of acoustic pulse. This new solver is developed using C++ based OpenFOAM toolkit and further tested for low Mach number flow test case. The analysis of simple expansion muffler for various structures, frequency ranges and …
-
Experimental studies of flapping foils for energy extraction
… sinusoidially 90° out of phase at a Reynolds number of 13,800. Energy extraction efficiencies of up to [eta] = 0.45 were found within a very small parametric region for small oscillation amplitudes while broad regions of appreciable efficiency were found at large oscillation amplitudes. The …
-
Wall-Jet Turbulence and Mixing Control by Way of a Pulsed Inlet Velocity
… the wall-normal turbulence intensity at a Strouhal number (Sr) of 0.05 and reduces the turbulence intensity in all directions at a Sr of 0.25. The incompressible wall-jet simulations show that a perturbation of magnitude 40% of the inlet velocity at a low Sr number of 0.0048 damps …
-
A Reduced-Order Model Bi-Modal Excitation of a Supersonic Planar Jet
… excitation is then examined for the fundamental Strouhal number 0.10, which has been identified as a dominant noise source. Cases were considered separately with adding the subharmonic and the harmonic as a means of reducing the amplitude of the fundamental. Adding the subharmonic had minimal …
-
Transition from laminar to turbulent flow around an airfoil
… an airfoil of arbitrary shape. A low-Reynolds-number k — e turbulence model including curvature effect was used to consider the gain and loss of turbulent kinetic energy. To include laminar sublayer into the computational domain, a multi-layer grid and a cubic-slpine grid were introduced …
Page 1 of 3