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Showing 1 to 20 of 28 for “"recirculation zones"”.
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Large-eddy simulations of recirculation zones in channel-type molten salt reactors
… main concern is the entrainment of fuel salt in recirculation zones and the subsequent creation of localized hotspots. Therefore, we investigated the presence of such recirculation zones and the effect of the tip-shape on turbulence and stationary vortices in the upper plenum. We analyzed the …
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Heat Transfer and Flow Measurements in Gas Turbine Engine Can and Annular Combustors
… flow core. The axial swirler induced larger recirculation zones at both the backside wall and the central area as the flow exits the swirler, and created a much more uniform rotational velocity distribution. The radial swirler however, produced greater rotational velocity as well as a thicker …
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Computational studies of viscoelastic multiphase flows
… in a viscoelastic fluid. In addition to the two recirculation zones at the equator of the bubble rising in a Newtonian fluid, two more recirculation zones exist in the wake of a bubble rising in viscoelastic fluids which influence the shape of a rising bubble. Also, the direction of motion of the …
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Computations of Flow Structures and Heat Transfer in a Dimpled Channel at Low to Moderate Reynolds Number
… transfer characteristics are dominated by the recirculation zones in the dimple with resulting augmentation ratios below unity. Flow transition is found to occur between Re = 1020 and 1130 after which both heat transfer and friction augmentation increase to values of 3.22 and 2.75, …
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3-DIMENSIONAL NUMERICAL AND EXPERIMENTAL STUDIES TO MODEL ARTIFICIAL HEART VALVES HEMODYNAMICS
… hemodynamics in details such as stagnation, recirculation zones and shear stresses. In this research, we established a numerical model using arbitrary Lagrangian Eulerien to study the hemodynamic performance of a bileaflet mechanical heart valve. The 3-dimensional numerical simulation was …
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Effect of inlet configurations on the aerodynamics of swirl combustors
… with non-swirling flow produced a uniform corner recirculation near the wall of the combustion chamber. The S-inlet made the corner recirculation zones unequal. The introduction of swirling in the flow created a central recirculation zone in addition to the corner recirculation zone. It was found …
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Thermoacoustic Analysis and Experimental Validation of Statistically-Based Flame Transfer Function Extracted from Computational Fluid Dynamics
… flows, multiple fuel injections points, and recirculation zones create a distribution of τ, which can vary widely making a statistical description more representative. Furthermore, increased flame lengths and higher frequency instabilities with short acoustic wavelengths challenge the …
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Two-dimensional finite element model for heat transfer in residential attic using an attic barrier system
… and thermal distributions in the attic. Several recirculation zones have been observed in the attic which seem to suggest the existences of convective cells. Also the effect of lowering the emissivity on the underside of the roof was investigated. This emissivity reduction seems to raise the …
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Linking cleaning performance to fluid flow via model soils
… complex flow features such as turbulence and recirculation zones, which have significant impacts on the cleanability of the processing equipment and the kinetics of soil removal. Instant coffee was identified as a suitable soluble model soil for the experiments, with thin, dry layers of soil …
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Numerical evaluation of aerodynamic roughness of the built environment and complex terrain
… up over crests of hills and also show larger recirculation zones. The current study also emphasized turbulence characterization behind hills. Finally a real complex terrain case of the well-known Askervein hill was simulated and the results validated against published field observations. In …
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Flow Field and Soot Formation Characteristics in Swirl-stabilized Non-premixed Turbulent Flames
… all flames featured pronounced inner and outer recirculation zones (IRZ, ORZ), each bounded by their corresponding inner and outer shear layers (ISL, OSL). Abel-inverted OH* intensity maps showed that primary reaction zones occurred in the vicinity of ISL. The central fuel jet penetrating into …
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Experimental and Numerical Study of Multi- Phase Flow in a Coaxial Air Jet
… but all the RANS models predicted a recirculation zone immediately downstream of the central jet that did not exist. The next paper described two phase flow created by the introduction of polymer particles into the air stream to the central air jet. A sheet of laser light and high …
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Swirling jets for the mitigation of hot spots and thermal Sstratification in the VHTR lower plenum
… of S permitted the analysis of the central recirculation zones (CRZ) impact on the LP flow field. At this point, several characteristics were found in common between the helicoid vortex and other axisymmetric, Newtonian, incompressible vortices found in the literature. This observation …
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PERFORMANCE ANALYSIS AND THE EFFECTS OF KEY PARAMETERS IN SOLID PARTICLE BEDS
… simulations showed that there is an increase in recirculation zones for increasing bed thickness to particle ratio. An approach to quantifying the effectiveness of solid particle beds has been proposed with heat transfer between fluid and particles using the CFD-DEM approach. A more efficient …
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Flow, Heat Transfer, and Pressure Drop Interactions in Louvered-Fin Arrays
… in flow velocity, large separation and recirculation zones, and an earlier transition to unsteady flow. At low Reynolds numbers, heat transfer is lower for louvers near the walls than for louvers far from them due to the large separation zones. At higher Reynolds numbers unsteady flow …
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Modelling and analysis of nonlinear thermoacoustic systems using frequency and time domain methods
… interaction, accounting for the presence of recirculation zones and temperature gradients; the second for imperfectly premixed flames, in which equivalence ratio fluctuations, modelled as a passive scalar field, dominate the heat release response. The second model was shown to agree …
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Blow-off in gas turbine combustors
… discussion on the velocity field and the related recirculation zones. The velocity and turbulence information obtained are particularly useful for providing data, which is crucial for validation of computational models. The second part describes an experimental investigation of non-premixed stable …
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Gas-phase synthesis of gold- and silica-coated nanoparticles.
… gas velocities across the wire are higher and recirculation zones are diminished. When gold is evaporated in the presence of silica nanoparticles, the silica aerosol is decorated by gold through either homogeneous gold nucleation and subsequent scavenging by the silica nanoparticles, or by …
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Modelling near-bank flow hydraulics
… reduction in the size and extent of separation zones at bank full stage, a movement of impingement points further downstream, and a continuation of the secondary flow within the fast streamtube further towards the bends exits. Bed/bank shear stress is mostly seen to decrease at shallow riffles …
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NUMERICAL AND EXPERIMENTAL ANALYSIS OF HEAT PIPES WITH APPLICATION IN CONCENTRATED SOLAR POWER SYSTEMS
… in the main condenser chamber, caused several recirculation zones to form in this region, which made the performance of the heat pipe convoluted. The recirculation zone shapes and locations affected by the geometrical features and the heat input, play an important role in the condenser …
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