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Showing 1 to 20 of 62 for “"separation bubble"”.
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Iced Airfoil Separation Bubble Measurements by Particle Image Velocimetry
… enhanced pressure recovery and reduced mean separation bubble length, each relative to the flowfield of a representative two-dimensional ice simulation. These effects appeared to result from the quasi-steady distribution of discrete, streamwise vortices which aided the turbulent entrainment …
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Low Reynolds Number Laminar Separation Bubble Control Using a Backward Facing Step
<p>The problem of a laminar separation bubble on the upper surface of a 9.5% thick airfoil operated at low Reynolds number (R<sub>N</sub> = 380,000) was investigated experimentally.</p> <p>An unmodified LRN-010 airfoil and a modified LRN-010 airfoil with a backward facing step on its upper surface …
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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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The development of kinetic models and simulation methods to study molecular fluctuations, modal response, shock-laminar separation bubble instabilities
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms
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The effect of free stream disturbances and control surface deflections on the performance of the Wortmann airfoil at low Reynolds numbers
… and flow-visualization studies. The laminar separation bubble which frequently occurs on the upper surface of the wing is found to dominate its performance and gives rise to a hysteresis loop for lift and drag. Changes in airfoil performance due to positive flap or control surface deflections …
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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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Aspect ratio effects on wings at low Reynolds numbers
… have a rather restricted effect on the laminar separation bubble. The disappearance of the bubble extends only for a small distance inboard from the tips. The size of the hysteresis loop and the Reynolds number at which hysteresis starts was found to be influenced by the aspect ratio. The …
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Unsteady modes in the flowfield about an airfoil with a leading-edge horn-ice shape
… reattachment location of the ice-induced laminar separation bubble downstream of the horn-ice shape using the surface hot-film array measurements. The maximum amount of unsteadiness in the iced-airfoil flowfield was observed to increase with increasing angle of attack. For a fixed angle of attack …
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Computational Analysis of Turbulent Flow Around NACA 4412 Airfoil with Open Source CFD Software
… that when ran at its critical angle of attack a separation bubble forms at the trailing edge of the airfoil. This separation bubble is a common occurrence in everyday flows around any bluff body or streamlined body that is not place perfectly parallel to the flow direction. The NACA 4412 flow …
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The hemisphere-cylinder at an angle of attack
… focused mainly on the development of the laminar separation bubble as a function of angle of attack, the conditions under which open and closed separation exist and the interaction between the separation bubble and the leeward vortices. A digital processing method was developed to convert flow …
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Numerical studies of the flow around an airfoil at low Reynolds number
… stability analysis. The behaviour of laminar separation bubbles formed on a NACA-0012 airfoil at Rec = 5 £ 104 and incidence 5± is investigated. Initially volume forcing is introduced in order to promote transition to turbulence. After obtaining sufficient data from this forced case, the …
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Effect of suction and cooling on the stability of subsonic and supersonic boundary layers
… and hence it increases the growth rates in the separation region. The coexistence of more than one instability mechanism makes a certain degree of wall cooling most effective. For the Mach numbers 0.5 and 0.8, the optimum wall temperatures are about 80% and 60% of the adiabatic wall temperature, …
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Effects of Free Stream Turbulence on Compressor Cascade Performance
… angles where transition exists within a laminar separation bubble, increasing free-stream turbulence suppressed the extent of the laminar separation bubble and led to an earlier turbulent reattachment.
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Acoustic influences on flow over an airfoil at low Reynolds numbers
… the transition process in the shear layer of the separation bubble on the upper surface of the airfoil. These disturbances could delay the deep leading edge stall or hasten stall recovery in some cases. A good agreement was found with the Crabtree criterion to predict the leading edge stall.
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Effects of Supercooled Large -Droplet Icing on Airfoil Aerodynamics
… was located downstream of 30% chord, and the separation bubble formed over the adverse pressure gradient of the clean airfoil, which started at 75% chord. The effect of the ice shape on the NLF 0414 was not as severe as on the NACA 23012m because the lift was much more aft loaded.
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An analysis of laminar jet reattachment: reattachment distance as a function of Reynolds number
… point. The pressure distribution within the separation bubble was considered in the analysis as well as the initial state of development of the reattaching jet. The assumption was also made that reattachment angle was independent of Reynolds number for a given plate inclination. A general …
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Experimental and numerical investigation of the flow structures at the rear of three-dimensional bluff bodies
… of the flow structures, where the slant separation bubble, longitudinal C-vortices and lower recirculation bubble are eliminated, whereas the upper recirculation bubble shifts toward the slant surface. This flow restructuring provides ~10.4% drag reduction and reduces surface …
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A potential flow model for separated flow around airfoils
… data required by the modelare the positions of separation points and the specification of the pressure coefficient at these points. Applications of this model include the case of flow normal to a flat plate, a separation bubble at the leading edge of a flat plate airfoil, and an airfoil fitted …
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Wind flow characteristics and their effects on low-rise buildings
Two fundamental flow phenomena, the separation bubble (SB) and conical vortex, over the roof (flat and rectangular) of the Texas Tech test building are studied in terms of flow characteristics and pressure-generating mechanisms. Major fmdings contribute to understanding the mechanisms of pressure …
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Near-Stall Loss Measurements in a CD Compressor Cascade with Exploratory Leading Edge Flow Control
… (passively) reduce the size of the leading edge separation bubble and thereby improve performance. Prior to the surveys, the acquisition and reduction software was modified to provide loss calculations using both mass-averaged and fully-mixed-out conditions for the upstream and downstream flows. …
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