Analysis of the Improvement in Performance Characteristics of S-Shaped Rectangular Diffuser by Momentum Injection Using Computational Fluid Dynamics

Singh, S. N.; Seshadri, V.; Chandel, Sunil; Gaikwad, Mahendra

doi:10.1080/19942060.2009.11015258

Cited by 10 publications

(11 citation statements)

References 7 publications

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“…This paper will therefore focus on turbulence and numerical scheme issues and make basic hypothesis regarding the choice of computational grids, which are, in the case presented here, kept constant for all simulations. The flow in a hydraulic turbine draft tube is an example of a turbulent flow which is a challenge for industrial CFD applications (Singh et al, 2009;El Drainy et al, 2009), due to the highly rotational, fluctuating and non-uniform flow that leaves the runner. This turbulent flow has a complex structure, and so, to achieve the necessary accuracy in a numerical prediction, an accurate mathematical model and robust numerical scheme must be available.…”

Section: Introductionmentioning

confidence: 99%

Assessment Study of K-ɛ Turbulence Models and Near-Wall Modeling for Steady State Swirling Flow Analysis in Draft Tube UsingFluent

Galván

Reggio

Guibault

2011

Engineering Applications of Computational Fluid Mechanics

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The accuracy of k-ε turbulence models for the swirling flow in the Turbine 99 draft tube is the subject of this work. The relation of the first-order upwind, second-order upwind, third-order upwind (QUICK) and Power Law schemes used with these models has been studied. As the turbulent flows are significantly affected by the presence of walls, the wall function and the near-wall models were tested for modeling the near-wall region. Two different grid concentrations near the wall y+1 and y+50 were used to study the flow behavior for case 1 of Turbine 99 Workshop III. Discussion is based on graphical results and by comparing numerical simulations and experiments in operational mode T (close to best efficiency). The results of this study indicate a very good representation of the flow at different cross sections by the RNG turbulence model but a poor level of convergence.

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Section: Introductionmentioning

confidence: 99%

Assessment Study of K-ɛ Turbulence Models and Near-Wall Modeling for Steady State Swirling Flow Analysis in Draft Tube UsingFluent

Galván

Reggio

Guibault

2011

Engineering Applications of Computational Fluid Mechanics

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“…Their wide use in engineering applications ranges from jet engines to air-conditioning systems. For example, they are used downstream of wind tunnel test sections to reduce the power consumption 3,4 , downstream of compressors, fans and turbines to increase the efficiency of these devices 5,6,7 , in the design of efficient micropumps 8 , and in inlet designs 9 . Designs of diffusers depend on the internal flow applications.…”

Section: Introductionmentioning

confidence: 99%

Volumetric Three-Component Measurements of Air Jet Flows of Different Diffuser Designs

Wahidi

Ölçmen

Lai

2015

53rd AIAA Aerospace Sciences Meeting

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The effects of three diffuser configurations on the near-field region have been experimentally evaluated with the goal to reduce the losses and noise of an existing large subsonic wind tunnel. Preliminary analysis were performed on over thirty diffuser designs and the most promising designs were selected for the experimental investigation. The two most promising diffusers are a 3.5°half-apex angle diffuser with a constant-area at the end, and a modified version of this diffuser with the addition of an annular conical diffuser after the flat section. The annular conical section consists of three concentric truncated cones. The air jet flow was measured with a volumetric three-component velocimetry. This experimental investigation is considered one of the first flow measurements using the volumetric three-component velocimetry in air flow. The measurement technique was assessed with a round free jet flow. The results of the round free jet show that the potential core region is shorter relative to results in literature. The results also show that in the nearfield region, the variations in the mean axial velocity decrease before the variations in the streamwise component of the Reynolds normal stresses, whereas the variations in the other components of the Reynolds normal stresses persist for a longer distance. Comparison between the existing diffuser and the modified diffusers shows that the modified diffusers reduce the velocity in the jet which supports the preliminary computational results. Also, the Reynolds shear stresses in the shear layer of these diffusers are suppressed. The modified diffuser with the an annular conical diffuser produces more reduction in the jet velocity suggesting its effectiveness in reducing the head losses. Also, this diffuser produces less turbulence, hence less noise. NomenclatureD = pipe diameter, D = 40.9 mm ReD = Reynolds number based on the pipe diameter and velocity in the pipe U∞ = jet exit velocity, U∞ = 27.6 m/sec u = streamwise component of the mean velocity v = normal component of the mean velocity w = transverse component of the mean velocity x = streamwise coordinate y = normal coordinate z = transverse coordinate 2 z = z component of the vorticity vector

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“…After that, a single cylinder having 0.3B diameter is placed across the width of the diffuser at inflexion plane. Approximately, 115 o sector of cylinder is in touch with the flow inside the duct [11].…”

Section: Geometrical Parametersmentioning

confidence: 99%

“…al. [11] did some parametric study used for secondary flow control by imparting momentum to the retarding fluid using rotating cylinder at the inflexion plane. The present research also concentrates towards improving the performance of the diffuser using momentum imparting technique adopted by Singh et.…”

Section: Introductionmentioning

confidence: 99%

Performance Improvement of S-shaped Diffuser Using Momentum Imparting Technique

Gopaliya¹,

Jain²,

Kumar³

et al. 2014

IOSRJMCE

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Analysis of the Improvement in Performance Characteristics of S-Shaped Rectangular Diffuser by Momentum Injection Using Computational Fluid Dynamics

Cited by 10 publications

References 7 publications

Assessment Study of K-ɛ Turbulence Models and Near-Wall Modeling for Steady State Swirling Flow Analysis in Draft Tube UsingFluent

Assessment Study of K-ɛ Turbulence Models and Near-Wall Modeling for Steady State Swirling Flow Analysis in Draft Tube UsingFluent

Volumetric Three-Component Measurements of Air Jet Flows of Different Diffuser Designs

Performance Improvement of S-shaped Diffuser Using Momentum Imparting Technique

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