A Modified Version of the RNG k – ? Turbulence Model for the Scale-Resolving Simulation of Internal Combustion Engines

Vesselin Krassimirov Krastev, Luca Silvestri and Giacomo Falcucci
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Vesselin Krassimirov Krastev: Department of Economics, Engineering, Society and Business Organization, University of Tuscia, 01100 Viterbo, Italy
Luca Silvestri: Department of Enterprise Engineering “Mario Lucertini”, University of “Tor Vergata”, 00133 Rome, Italy
Giacomo Falcucci: Department of Enterprise Engineering “Mario Lucertini”, University of “Tor Vergata”, 00133 Rome, Italy

Energies, 2017, vol. 10, issue 12, 1-16

Abstract: The unsteady and random character of turbulent flow motion is a key aspect of the multidimensional modeling of internal combustion engines (ICEs). A typical example can be found in the prediction of the cycle-to-cycle variability (CCV) in modern, highly downsized gasoline direct injection (GDI) engines, which strongly depends on the accurate simulation of turbulent in-cylinder flow structures. The current standard for turbulence modeling in ICEs is still represented by the unsteady form of Reynold-averaged Navier Stokes equations (URANS), which allows the simulation of full engine cycles at relatively low computational costs. URANS-based methods, however, are only able to return a statistical description of turbulence, as the effects of all scales of motion are entirely modeled. Therefore, during the last decade, scale-resolving methods such as large eddy simulation (LES) or hybrid URANS/LES approaches are gaining increasing attention among the engine-modeling community. In the present paper, we propose a scale-resolving capable modification of the popular RNG k – ? URANS model. The modification is based on a detached-eddy simulation (DES) framework and allows one to explicitly set the behavior (URANS, DES or LES) of the model in different zones of the computational domain. The resulting zonal formulation has been tested on two reference test cases, comparing the numerical predictions with the available experimental data sets and with previous computational studies. Overall, the scale-resolved part of the computed flow has been found to be consistent with the expected flow physics, thus confirming the validity of the proposed simulation methodology.

Keywords: internal combustion engines; turbulence modeling; RNG; scale-resolving simulation; cycle-to-cycle variability (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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