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Journal ArticleDOI

Numerical simulation of turbulent flow in a Ranque–Hilsch vortex tube

TL;DR: In this article, numerical simulations of the internal flow in a commercial model of a Ranque-Hilsch vortex tube (RHVT) operating in jet impingement were performed by both RANS and LES techniques.
About: This article is published in International Journal of Heat and Mass Transfer.The article was published on 2009-11-01. It has received 112 citations till now. The article focuses on the topics: Vortex tube & Reynolds-averaged Navier–Stokes equations.
Citations
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Journal ArticleDOI
TL;DR: In this article, the effect of the cyclone inlet dimensions on the performance and flow field pattern has been investigated computationally using the Reynolds stress turbulence model (RSM) for five cyclone separators.

306 citations

Journal ArticleDOI
TL;DR: In this paper, a critical review of current explanations on the working concept of a vortex tube is presented, and hypotheses of pressure, viscosity, turbulence, temperature, secondary circulation and acoustic streaming are discussed.

152 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of changing the dust outlet geometry on the flow field pattern and performance of air cyclones was investigated and the results showed that the maximum tangential velocity is almost the same for the four tested cyclones.

100 citations

Journal ArticleDOI
TL;DR: In this article, the effects of number of inlets, tube length and diameter of vortex tube on temperature, flow rates passing through the vortex tube are investigated, and the authors conclude that the passing flow rate from a cold outlet is increased as its diameter increase and by increasing the length of the vortex tubes, the passing mass flow rates from the cold and hot cross-sections slightly increased and slightly increased, respectively.

100 citations

Journal ArticleDOI
TL;DR: In this article, the authors provide an updated and a comprehensive account of the state of the art research on Wells turbine and draw a roadmap for the contemporary challenges which may hinder future reliance on such systems in the renewable energy sector.
Abstract: In the past twenty years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column (OWC) concept. Wells turbine is one of the most efficient OWC technologies. This article provides an updated and a comprehensive account of the state of the art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of computational fluid dynamics (CFD) for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W-T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last five years, indicates that there is a trend that considerably depends on the CFD method.

84 citations

References
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Book
07 Aug 1998

1,924 citations


"Numerical simulation of turbulent f..." refers background or methods in this paper

  • ...From the values of this parameter it follows that the grid convergence index (GCI [14]) can be obtained for different grids (Table 2)....

    [...]

  • ...The achieving of the asymptotic range for the discretization method order used (second order) was verified too, determining the approximate constancy of EP parameter, as established in [14]....

    [...]

Book
01 Mar 2001

1,590 citations

Journal ArticleDOI
TL;DR: In this paper, a compressible generalization of the linear combination of the Smagorinsky model and scale-similarity model, in terms of Favre-filtered fields, is obtained for the subgrid-scale stress tensor.
Abstract: New subgrid-scale models for the large-eddy simulation of compressible turbulent flows are developed and tested based on the Favre-filtered equations of motion for an ideal gas. A compressible generalization of the linear combination of the Smagorinsky model and scale-similarity model, in terms of Favre-filtered fields, is obtained for the subgrid-scale stress tensor. An analogous thermal linear combination model is also developed for the subgrid-scale heat flux vector. The two dimensionless constants associated with these subgrid-scale models are obtained by correlating with the results of direct numerical simulations of compressible isotropic turbulence performed on a 96 (exp 3) grid using Fourier collocation methods. Extensive comparisons between the direct and modeled subgrid-scale fields are provided in order to validate the models. A large-eddy simulation of the decay of compressible isotropic turbulence (conducted on a coarse 32(exp 3) grid) is shown to yield results that are in excellent agreement with the fine-grid direct simulation. Future applications of these compressible subgrid-scale models to the large-eddy simulation of more complex supersonic flows are discussed briefly.

714 citations

Journal ArticleDOI
TL;DR: In this paper, a nonlinear K-l and K-e model is proposed to predict the normal Reynolds stresses in turbulent channel flow much more accurately than the linear model, and the nonlinear model is shown to be capable of predicting turbulent secondary flows in non-circular ducts.
Abstract: The commonly used linear K-l and K-e models of turbulence are shown to be incapable of accurately predicting turbulent flows where the normal Reynolds stresses play an important role. By means of an asymptotic expansion, nonlinear K-l and K-e models are obtained which, unlike all such previous nonlinear models, satisfy both realizability and the necessary invariance requirements. Calculations are presented which demonstrate that this nonlinear model is able to predict the normal Reynolds stresses in turbulent channel flow much more accurately than the linear model. Furthermore, the nonlinear model is shown to be capable of predicting turbulent secondary flows in non-circular ducts - a phenomenon which the linear models are fundamentally unable to describe. An additional application of this model to the improved prediction of separated flows is discussed briefly along with other possible avenues of future research.

644 citations