Numerical study of turbulent diesel flow in a pipe with sudden expansion

Koronaki, Eleni D.; Liakos, H. H.; Founti, M.; Markatos, N.C.

doi:10.1016/s0307-904x(00)00055-x

Cited by 27 publications

(17 citation statements)

References 19 publications

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“…The RNG turbulence model is more responsive to the effects of rapid strain and streamlines curvature, flow separation, reattachment and recirculation than the standard k-ℇ model. The RNG k-ℇ model gives the best predictions of all the two-equation models as far as the velocity field, the turbulence kinetic energy and the recirculation length are concerned [16]. The RNG derived k-ℇ model gave very good predictions for a pipe with sudden expansion, especially when non-equilibrium wall-functions were implemented [17].…”

Section: Numerical Implementationmentioning

confidence: 95%

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Three-dimensional Numerical Analysis Of Heat Transfer Characteristics Of Solar Parabolic Collector With Two Segmental Rings

Ghasemi¹,

Ranjbar²,

Ramiar³

2013

J. Math. Computer Sci.

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In this article, the heat transfer characteristics of parabolic solar collector with two segmental rings has been investigated numerically. The effect of distance between porous two segmental rings on the heat transfer coefficient of the collector has been studied. The heat transfer fluid is Therminol 66 and the model is solved by RNG k-ℇ turbulent model using Computational Fluid Dynamics (CFD) package, FLUENT. This numerical simulation is implemented for different distances between two segmental rings, the results show that use of two segmental rings in tubular solar absorber enhances the heat transfer characteristics of solar parabolic collector. Also by decreasing the distance between two segmental rings,the heat transfer coefficient increases.

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Section: Numerical Implementationmentioning

confidence: 95%

“…The discretization scheme used for pressure is body force weighted to take the density variations in consideration. The solution is based on pressure correction method and uses SIMPLEC algorithm [16]. The first order upwind differencing scheme is used for momentum and energy equations.…”

Section: Numerical Implementationmentioning

confidence: 99%

Three-dimensional Numerical Analysis Of Heat Transfer Characteristics Of Solar Parabolic Collector With Two Segmental Rings

Ghasemi¹,

Ranjbar²,

Ramiar³

2013

J. Math. Computer Sci.

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“…The result is that the RNG derived closures perform well in some¯ows but worse than the standard models in other¯ows (Hanjalic, 1996). Characteristic examples of ows including combustion and heat-transfer where the RNG k±e model has demonstrated antithetic performance are the sudden expansion and sudden contraction geometries; in the sudden expansion case the model performed better than the standard k±e and the opposite happened in the sudden contraction geometry (Koronaki et al, 2000). The RNG k±e model is used here in order to account indirectly for the non-isotropic features of the turbulent ame, without considerably increasing the computational time and storage requirements in comparison with the higher order Reynolds stress model.…”

Section: Turbulence Model 231 Two-equation Modelsmentioning

confidence: 99%

Modeling the characteristic types and heat release of stretched premixed impinging flames

Liakos

Founti

Markatos

2001

Computational Mechanics

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A numerical code has been developed for the simulation of the impingement of a turbulent jet on a plane surface. The performance of three turbulence models is assessed under isothermal conditions. Predictions are compared with experimental data from the literature. Based on the results an appropriate turbulence model is selected to model a premixed jet¯ame impinging on a solid surface. Mass transfer and combustion are modeled with a two-equation model simulating volumetric and kinetically controlled chemical reaction rates. Modeling of heat transfer accounts for convection and radiation effects. Results show that under high pressure environment turbulent premixed¯ames are of wrinkled-thickened type near the outlet of the nozzle (free jet region) and of wrinkled reaction sheets in the area near the surface (impingement region and radial wall jet). The results establish that appropriate choice of turbulence and combustion models can lead to accurate prediction of the¯ow characteristics.

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“…In the nearwall region, the non-equilibrium wall function of Launder and Spalding (1972) was set. Both Koronaki et al (2001) and Siriboonluckul and Juntasaro (2007) report that, for separated flows, the k-ε RNG turbulence model with non-equilibrium wall functions works better in the near-wall regions with respect to the standard wall functions. In all cases, it was checked that the application of such condition was consistent with the non-dimensional distance of the first grid points from the walls.…”

Section: Computational Domain and Boundary Conditionsmentioning

confidence: 99%

Numerical investigation of solid-liquid slurry flow through an upward-facing step

Messa¹,

Malavasi²

2013

Journal of Hydrology and Hydromechanics

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Abstract:The flow of a solid-water mixture through an upward-facing step in a channel is numerically investigated. The effect of expansion ratio, mean solids volume fraction and particle diameter on the velocity field, pressure distribution and solid volume fraction field is studied. Expansion ratios of 0.50 and 0.67, particle diameter of 125 µm and 440 µm and mean solid volume fraction between 0.05 and 0.20 are considered. Particle density is 2465 kg m -3 . An Eulerian twofluid model is used to simulate the flow. Due to the lack of experimental data, the model was validated by comparison to other numerical investigations and to experimental data about the horizontal pipe case. Afterwards, it is studied the effect of the above mentioned parameters upon the degree of coupling between the phases and the extension of the disturbance region in the pressure and solid volume fraction fields downstream the step. Parameters of engineering interest, such as the reattachment length and the pressure recovery downstream the enlargement, are investigated.

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Numerical study of turbulent diesel flow in a pipe with sudden expansion

Cited by 27 publications

References 19 publications

Three-dimensional Numerical Analysis Of Heat Transfer Characteristics Of Solar Parabolic Collector With Two Segmental Rings

Three-dimensional Numerical Analysis Of Heat Transfer Characteristics Of Solar Parabolic Collector With Two Segmental Rings

Modeling the characteristic types and heat release of stretched premixed impinging flames

Numerical investigation of solid-liquid slurry flow through an upward-facing step

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