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 34 for “"tip vortex"”.
-
Studies in Tip Vortex Formation, Evolution and Control
… is used to study the formation and evolution of tip vortices from fixed wings and rotary blades. The numerical error is reduced by using high order accurate schemes on appropriately refined meshes. For vortex evolution problems, the equations are solved on multiple {\em overset} grids that ensure …
-
An experimental investigation of interacting wing-tip vortex pairs
The interactions of trailing vortex pairs shed from the tips of two rectangular wings have been studied through helium bubble flow visualizations and extensive hot wire velocity measurements made between 10 and 30 chord lengths downstream. The wings were placed tip to tip at equal and opposite …
-
Propeller tip vortex impingement and vibratory force on a rudder.
Massachusetts Institute of Technology. Dept. of Ocean Engineering. Thesis. 1974. M.S. (Also M.S. in Mechanical Engineering).
-
The Effect of Butterfly Inspired Scales on Wing Tip Vortex Development
… on the scale patterning found on the wing tips, where scales are three times the size of the traditional scales that coat the wing surface. It was hypothesized that the long wing tip scales of the Monarch butterfly act to modify the growth and development of the tip vortex in order to …
-
An Investigation of Avian Wing Tip Vortex Generation Using a Biomimetic Approach
… and laser visualization testing highlighted the vortex generation of multiple primary feathers, as well as large-scale flow deviations in the vicinity of the feathers. A total pressure rake and total pressure probe were used to create detailed plots of the ratio of the local velocity to …
-
Acoustics comparison of a novel reduced tip vortex rotary blade and a traditional blade
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-12-01
-
Characterization of wake- and tip-vortex-induced unsteady blade response in multistage compressor environment
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002.
-
Comparison of RANS Modeling to Dual-Plane PIV Measurements of the Turbulent Tip Vortex Trailed from a Hovering Rotor
… study the development and turbulent decay of the tip vortices in the wake produced by a hovering rotor. The computational results were compared to detailed, dual plane Particle Image Velocimetry (PIV) measurements of a turbulent tip vortex trailed from a single-bladed rotor. The work investigated …
-
Effects of Turbulence Modeling on RANS Simulations of Tip Vortices
… flows. The simulation of aerodynamic wing-tip vortices is used as a test bed. The primary configuration is flow over an isolated finite wing with aspect ratio, , and Reynolds number, . Tip-vortex velocity profiles, vortex core and wake turbulence levels, and Reynolds stresses are compared …
-
Coaxial contrarotating twin rotor aerodynamics
… has been paid to the characteristics of the tip vortex, namely, vortex strength, structure and decay. Equations are presented which describe both the vortex core and the complete structure of a rolled-up tip vortex. These equations are utilised with., conventional strip theory to enhance the …
-
An Improved Prescribed Wake Analysis for Wind Turbine Rotors
The trajectories of the tip vortices of a model wind turbine rotor are quantitatively tracked for twenty-seven separate test conditions. Three pitch angles are used (-8°, -3° and 3°). Three tip speed ratios are examined (2, 5 and 10). Finally, data for rotors with one, two and three …
-
Design and aerodynamic analysis of an airfoil with a bioinspired leading edge device for stall mitigation at low Reynolds number operation
… mean chord of the airfoil, is varied to modulate tip-vortex strength, while the alula deflection is varied to modulate the distance of the tip vortex to the wing surface. Boundary layer velocity profile measurements taken at x/c = 1.25 along the chord length and at three locations along the span …
-
Numerical Investigation of the Wake of a Rectangular Wing
Wakes of lifting bodies contain vortex sheets that roll up into strong streamwise vortices. The long time behavior of such vortices depends on the turbulence in the wake and the stability characteristics of the vortices themselves. In the near wake of a rectangular wing the flow field consists of a …
-
Dynamic wind turbine wake trajectory control: Strategies and real-time validation
… detection, this dissertation proposes the tip-vortex-based tracking approach, which tracks the instantaneous strengths of the streamwise 1P spectral energy peaks as the wake interface oscillate around a desired position. It was demonstrated through wind tunnel experiments that yaw-based …
-
An output-based adaptive and high-order method for a rotor in hover
… simulation of rotorcraft wakes and blade-vortex interactions continues to be a challenge, the output-based adaptation scheme is used with thrust as the output of interest to refine the mesh. The result is a solution with less than three million degrees of freedom that is capable of …
-
Aerodynamic and aeroacoustic design of small unmanned aircraft system propellers at low Reynolds numbers.
… modified, and five bladed propellers reducing tip vortex strength and noise generation. Results showed measurable far field sound decay and five bladed noise reductions of 5 dBA. Three motors compared propeller power consumption and resulted in increased electrical efficiencies of 14.5% and …
-
A Computational Study of Axial Compressor Rotor Casing Treatments and Stator Land Seals
… each of these features. It was found that rotor tip vortex control plays a large part in the surge margin gains from a circumferential groove casing treatment. The efficiency gains of knife seals were dependent primarily on the gap size of the seals.
-
A study on the efficient numerical analysis for the prediction of full-scale propeller performance using CFD
… the pressures, friction, streamlines, and tip vortex formation characteristics.The findings of this research study support the use of a small value of wall y+ (i.e., y+<1) for the model scale simulations, but the effect of the wall y+ is negligible in full-scale. This study also …
-
Numerical modeling and simulation of cavitating flows in different regimes
… for large eddysimulation (LES) of multiphase cavitating flows over different cavitation regimes. Unstructured grids are considered to enable complex geometries to be considered. The dissertation has the following major components: (i) a compressible homogeneous approach for a mixture …
-
A fully numerical lifting line method for the design of heavily loaded marine propellers with rake and skew
… comparison of the influence of the effect of tip vortex roll-up is done. A lifting surface method with fully aligned wake is developed and used to correct the optimum distribution of pitch and camber obtained by the new lifting line method. The resulting geometries, operating under …
Page 1 of 2