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Showing 1 to 20 of 22 for “"Separation Control"”.
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Flow separation control with rotating cylinders
… and reduce efficiency. Applying active flow separation control to ocean vehicles would reduce resistance during maneuvers and thereby improve maneuvering performance. In this thesis I discuss experiments in active separation control in a simpler, but still relevant, two-dimensional flow past …
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Unsteady separation control on wind turbine blades
… and sustained yaw misalignment. The unsteady separation due to dynamic stall can lead to excessive loads, much larger than the design loads for the turbine, and vibrations in the blade, leading to fatigue damage. Furthermore, massive flow separations can lead to performance losses for the …
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Flow Separation Control Using Synthetic Jets on a Flat Plate
… to assess the effect of synthetic jets on flow separation. CFD simulation is conducted for laminar flow over a flat plate using the commercial software ANSYS FLUENT. The oscillating zero mass jet flow is simulated by imposing a harmonically varying boundary condition on the wall surface.</p> …
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Boundary Layer Separation Control on a Salient Back-facing Ramp
… and the performance of the serration flow control devices on a salient edge where the laminar boundary layer separation is two-dimensional. Three geometries of serrations: a sharp delta, a double delta and a divergent delta are examined on 15° and 30° deflected, backward-facing ramps. …
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Active and passive separation control for drag reduction of a maneuvering hull form
Boundary layer separation is a source of large fluid dynamic forces on many engineered vehicles and structures, limiting the speed and efficiency at which we transport people and goods. The maneuvering of ocean and air vehicles in particular is limited by resistance due to cross-flow separation. …
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Open-loop and closed-loop trailing-edge separation control on a natural laminar flow airfoil
Active Unsteady Flow Control experiments were performed on a Natural Laminar Flow, NLF 0414 airfoil at Re = 1.0 × 10(6) in a 3-ft × 4-ft low-speed, low-turbulence wind tunnel. The NLF 0414 was designed with a region of favorable pressure gradient extending almost 70% of the chord on the upper …
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The development of passive flow control vortices
… floor of a 350mm by 250mm wind tunnel and had a separation zone on its trailing edge.<br/>Surface flow visualisation was used to select VVG spacings and SJVG velocity ratios for effective separation control and investigate surface flow. Instantaneous and mean parameters downstream of the VVG and …
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An Investigation of Dolphin-Groove Inspired Surface Patterning on Flow Control
… in many flow applications is boundary layer separation; this study investigates the passive separation control mechanism that could result from the micro-grooves found on dolphin skin (Tursiops truncates). A water tunnel was used to study a turbulent boundary layer over rigid 3D printed …
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Passive Turbulent Boundary Layer Control through 3D-Printed Dolphin Skin
… truncates) skin to mitigate boundary layer separation as a form of passive flow control, energizing the flow near the wall. A water tunnel generates a tripped turbulent boundary layer across a vertical test plate, and a rotating cylinder induces flow separation by creating an adverse …
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Development of a Sensor for Inflight Detection of Three-Dimensional Flow Separation on a Wing
… for a sensor capable of detecting flow-field separation on an airplane wing during routine flight operations. A sensor of this type could lead to both improved flight safety and increased performance. It would also contribute to future separation control technologies. A new idea is presented …
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Investigation of Scaling Effects for a Synthetic Jet Actuator Using High and Low Fidelity Analyses
… thrust generator or fixed on an airfoil for flow separation control. A Computational Fluid Dynamics (CFD) model was created, using Ansys-CFX, to be validated against referred publications. The use of mesh adaption is discussed. This baseline model was then used to complete a scaling analysis using …
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Design of Synthetic Jet Actuator for Flight Control of Small UAV
… Glauert wing cross-section for Active Flow Control. Apart from lift enhancement, drag reduction, or separation control, etc; LCO suppression might be possible by modifying the boundary layer through the use of these actuators. For initial investigation, a wing section with span of 12.4 cm …
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ΑΥΤΟΠΡΟΣΑΡΜΟΖΟΜΕΝΟΙ ΑΛΓΟΡΙΘΜΟΙ ΑΥΤΟΜΑΤΟΥ ΕΛΕΓΧΟΥ: ΣΥΓΚΡΙΤΙΚΗ ΥΠΟΛΟΓΙΣΤΙΚΗ ΑΝΑΛΥΣΗ-ΠΑΡΑΛΛΗΛΙΣΜΟΣ
… WAS THE STUDY OF BOTH KNOWN AND NEW ADAPTIVE CONTROL ALGORITHMS, FOR LINEAR, STOCHASTIC, DISCRETE TIME SYSTEMS, WITH UNKNOWN PARAMETERS. WE CONSIDERED FIRST THE CASE WHERE THE SYSTEM MODEL IS IN STATE SPACE FORM. THE TWO WELL KNOWN ADAPTIVE CONTROL ALGORITHMS, FOR SYSTEMS WITH UNKNOWNBUT …
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The Effects of Vortex Generator Jet Frequency, Duty Cycle, and Phase on Separation Bubble Dynamics
… have proven to be effective in minimizing the separation losses on low-pressure turbine blades at low Reynolds numbers. Experimental data collected using phase-locked particle image velocimetry and substantiated with a hot-film anemometer were used to answer fundamental questions about the …
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Aerodynamics and multi-fidelity surrogate modelling of an inverted wing with vortex generators in ground effect
… layer vortex generator type, can be effective at controlling flow separation, with a resultant improvement in downforce within relatively low drag penalty. The results also reveal fundamental vortex characteristics for flow separation control.<br/><br/>A computational study is performed by …
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Numerical and experimental study on the ability of dynamic roughness to alter the development of a leading edge vortex
… methods associated with laminar boundary layer separation control. Although these methods have shown promise, they suffer from the drawback that they exhaust more energy than is gained by flow control, while also only being effective at certain flight regimes.;The research described herein …
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Effects of Spanwise and Discrete Disturbances on Separating Boundary Layers on Low Pressure Turbine Blades
… For these operating conditions, a large separation bubble forms on the blade suction surface, beginning at 59% cx and reattaching at 86% cx on the L1M blade and a non-reattaching bubble beginning at 68% cx on the Pack B. A spanwise row of discrete vortex-generating jets located at 59% cx …
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Phase Locked Flow Measurements of Steady and Unsteady Vortex Generator Jets in a Separating Boundary Layer
… been found to be an effective method of active separation control on the suction side of a low pressure turbine (LPT) blade at low Reynolds numbers. The flow mechanisms responsible for this control were studied and documented in order to provide a basis for future improvements in LPT design. …
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Ducted Fan Aerodynamics and Modeling, with Applications of Steady and Synthetic Jet Flow Control
… vehicle flight and therefore require complex control algorithms. In particular, they exhibit a large nose-up pitching moment during wind gusts and when transitioning from hover to forward flight. Understanding ducted fan aerodynamic behavior and how it can be altered through flow control …
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Numerical Modeling of Synthetic Jets in Quiescent Air with Moving Boundary Conditions
Flow control is a key factor in optimizing the performance of any vehicle moving through fluids. Particularly, in aerodynamics there are many potential benefits for implementing synthetic jets to achieve aircraft designs with less moving parts, uper- maneuverability, and separation control for fuel …
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