Comparative study of higher order turbulence models for compressible separated flows

Abstract This paper presents a new higher-order bounded scheme, WACEB, for approximating the convective fluxes in the transport equations. The weighted-average formulation is used for interpolating the variables at cell faces and the weighted-average coefficient is determined from normalized variable formulation and total variation diminishing (TVD) constrains to ensure the boundedness of solution. The new scheme is tested by solving three problems: 1) a pure convection of a box-shaped step profile in an oblique velocity field; 2) a sudden expansion of an oblique velocity field in a cavity, and; 3) a laminar flow over a fence. The results obtained by the present WACEB were compared with the UPWIND and the QUICK schemes and showed that this scheme has at least the second-order accuracy while ensuring boundedness of solutions. Moreover, it was demonstrated that this scheme produces results that better agree with the experimental data in comparison with other schemes.

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COMPARATIVE STUDY OF THE FLOW ANALYSIS RESULTS FOR BUTTERFLY VALVE USING DIFFERENT TURBULENCE MODELS

Journal of computational fluids engineering ◽

10.6112/kscfe.2021.26.1.113 ◽

2021 ◽

Vol 26 (1) ◽

pp. 113-120

Author(s):

J.H. Bae ◽

G.H. Lee

Keyword(s):

Comparative Study ◽

Flow Analysis ◽

Turbulence Models ◽

Butterfly Valve

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Computational Study of Gas Turbine Blade Cooling Channel

2010 14th International Heat Transfer Conference, Volume 5 ◽

10.1115/ihtc14-22920 ◽

2010 ◽

Cited By ~ 3

Author(s):

R. S. Amano ◽

Krishna Guntur ◽

Jose Martinez Lucci

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Gas Turbine ◽

Turbulence Models ◽

Flow Patterns ◽

Higher Order ◽

Secondary Flows ◽

Complex Flow ◽

Cooling Performance ◽

Cooling Channels

It has been a common practice to use cooling passages in gas turbine blade in order to keep the blade temperatures within the operating range. Insufficiently cooled blades are subject to oxidation, to cause creep rupture, and even to cause melting of the material. To design better cooling passages, better understanding of the flow patterns within the complicated flow channels is essential. The interactions between secondary flows and separation lead to very complex flow patterns. To accurately simulate these flows and heat transfer, both refined turbulence models and higher-order numerical schemes are indispensable for turbine designers to improve the cooling performance. Power output and the efficiency of turbine are completely related to gas firing temperature from chamber. The increment of gas firing temperature is limited by the blade material properties. Advancements in the cooling technology resulted in high firing temperatures with acceptable material temperatures. To better design the cooling channels and to improve the heat transfer, many researchers are studying the flow patterns inside the cooling channels both experimentally and computationally. In this paper, the authors present the performance of three turbulence models using TEACH software code in comparison with the experimental values. To test the performance, a square duct with rectangular ribs oriented at 90° and 45° degree and placed at regular intervals. The channel also has bleed holes. The normalized Nusselt number obtained from simulation are validated with that of experiment. The Reynolds number is set at 10,000 for both the simulation and experiment. The interactions between secondary flows and separation lead to very complex flow patterns. To accurately simulate these flows and heat transfer, both refined turbulence models and higher-order numerical schemes are indispensable for turbine designers to improve the cooling performance. The three-dimensional turbulent flows and heat transfer are numerically studied by using several different turbulence models, such as non-linear low-Reynolds number k-omega and Reynolds Stress (RSM) models. In k-omega model the cubic terms are included to represent the effects of extra strain-rates such as streamline curvature and three-dimensionality on both turbulence normal and shear stresses. The finite volume difference method incorporated with the higher-order bounded interpolation scheme has been employed in the present study. The outcome of this study will help determine the best suitable turbulence model for future studies.

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