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Showing 1 to 18 of 18 for “"wake vortices"”.
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Dynamics of longitudinal wake vortices
In the present study, the mid-field vortex wake is investigated. For the most part, the results focus on the motion of a pair of co-rotating vortices prior to merger, both in and out of ground effect. However, in order to verify the experimental and computational methods, results for single …
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Optical measurement of random-sized particles in wing tip wake vortices
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1992.
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The effect of Whitcomb winglets and other wingtip modifications on wake vortices
… wingtip configurations to determine their wake vortex characteristics. The trailing wingtip vortex was probed by a 1/8 inch diameter five hole yawhead pressure probe in the VPI & SU Stability Wind Tunnel. The vortex tangential and axial velocity profiles are compared at five and twenty …
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Mechanisms of Sediment Entrainment and Transport in Rotorcraft Brownout
… of the temporal evolution of the rotor wake in ground effect simultaneously with the processes of sediment entrainment and transport by the rotor flow. High-resolution near-wall PIV measurements showed that large excursions in the surface boundary layer were produced by the convecting …
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Numerical methods for the unsteady incompressible Navier-Stokes equations and their application to the Direct Numerical Simulation of turbulent flows
… the flow. A new origin for the formation of the wake vortices has been discovered for both pulsed and unpulsed jets. Pulsing is shown to drastically change the jet spreading and penetration and to increase the mixing of the jet with the crossflow. A significant asymmetry affecting primarily the …
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Phase front analysis of laminar vortex streets
… centres along the preceding vortexin the near wake. Vortices are located at places where the phase in each cycle is 0 or n. The phase is defined from a Kirchhoff-type phase-amplitude integral which is derived from the Biot-Savart law. Model predictions agree with reported experimental results …
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Passive wake detection using seal whisker-inspired sensing
… display the harbor seal's ability to track the wake of an object several seconds after it swam by. In this work, I elucidate the basic fluid mechanisms that seals may employ to accomplish this detection. Key are the unique vortex-induced vibration (VIV) properties resulting from the geometry of …
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A computational and experimental investigation of the propulsive and lifting characteristics of oscillating airfoils and airfoil combinations in incompressible flow
… oscillating airfoil on the formation of the wake vortices. Furthermore, a flow visualization experiment was conducted in the NPS low speed wind tunnel, which demonstrated the beneficial influence of a secondary airfoil oscillating in the vicinity of a stationary airfoil at …
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Determination of Bragg Scatter in an Aircraft Generated Wake Vortex System for Radar Detection
… detection and tracking of wingtip generated wake vortices is important for hazard avoidance especially near airports. Aircraft that fly through these hazardous vortices experience sudden induced roll. Experiments have demonstrated that there is sufficient radar cross section for remote …
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Effects of upstream wake phasing on the performance of transonic compressors
The effect of the upstream wake phase on the work input (i.e., rise in stagnation enthalpy across the blade row) of a transonic rotor is examined computationally and analytically. It is found that the compressor work depends on the path followed by the wake vortices as they travel through the rotor …
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Analysis of Potential Wake Turbulence Encounters in Current and NextGen Flight Operations
Wake vortices pose a threat to a following aircraft, because they can induce a roll and compromise the safety of everyone on board. Caused by a difference in pressure between the upper and the lower part of the wings, these invisible flows of air are a major hazard and have to be avoided by …
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Variable Fidelity Studies in Wake Vortex Evolution, Safety, and Control
… investigation toolkit for analysis and reporting wake vortex safety system (SITAR WVSS) code, which is a dynamic low-fidelity model addressing generation, evolution, and interaction of the leader-aircraft wake vortex with the follower-aircraft lifting surfaces.</p> <p>The first part of the …
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Passive wake detection using seal whisker-inspired sensing
… harbor seal's extraordinary ability to track the wake of an object several seconds after it has swum by. They do so despite having auditory and visual cues blocked, pointing to use of their whiskers as sensors of minute water movements. In this work, I elucidate the basic uid mechanisms that seals …
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Modeling of Nonlinear Unsteady Aerodynamics, Dynamics and Fluid Structure Interactions
… some of the major assumptions such as (1) flat wake, (2) small angle of attack, (3) small disturbances to the mean flow components, and (4) time-invariant free-stream. The kinematics of the wake vortices is simulated numerically while the wake and bound circulation distribution and, …
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Structure and Dynamics of a Reacting Jet Injected into a Vitiated Crossflow in a Staged Combustion System
… The time averaged flow field shows a steady wake vortex very similar to that seen in the wake of a cylindrical bluff body which helps to stabilize the reaction zone within the wake of the jet. Jet with J = 8 had a deeper penetration into the crossflow as compared to J = 3 jet. Velocity field …
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The effect of wing flexibility on ride comfort in formation flight
… Nastran Aeroelastic User's Guide. The trailing wake vortices shed by the lead aircraft in formation flight were considered to have a solid core using the Burnham-Hallock Model. The optimal positioning of the trailing aircraft in a two-aircraft formation was discussed and all subsequent …