To choose a turbulence model for numerical simulation of nonstationary processes in the combustion chamber of gas turbine engines

Аuthors

Donskikh V. V., Savchuk А. Т.^*, Yakovlev A. A.

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: atsavchuk@mai.education

Abstract

The choice of an applicable turbulence model for modeling the intracameral processes of a gas turbine engine (GTE) is one of the decisive steps in the process of numerical modeling of “burning” flows in the CC (combustion chamber) of a GTE, which determine both the flow pattern and combustion. The using of an inadequate turbulence model will lead to nonobvious false conclusions in the process of designing and comprehensive engine development as a high-reliability product. Most of the approaches, presented by various researchers and science teams, propose to use in computational practice а turbulence models, implemented in various CFD (Computational Fluid Dynamics) software (ANSYS.Fluent/CFX, FlowVision, FloEFD…) with verification of the choice of turbulence model based on the results of correlation of numerical modeling data with physical experiments without formation of a formal mathematical feature taking into account the mesh effect, allowing to determine the applicable turbulence model. The Y+ criterion, widely used in computational practice, allows one to evaluate the correctness of the computational process only in the near-wall inflation layers of the computational mesh without taking into account the influence of the entire array of generated grid regions as the part of the entire problem. The complex mutual influence of the main factors for the successful correlation of the mathematical model and the physical experiment, namely: meshes, the applied turbulence model and the solver used, is currently an open area of research. In the presented article the authors propose for consideration a formal sign of adequacy of the applied turbulence model with taking into account the mesh effect based on the assumption of a single-domain stochastic nature of oscillations of primitive gas-dynamic variables (temperature/velocity/pressure) and the mass flow rate of the GAM (gas-air mixture) in the outlet section of the CC under the condition of the known stable opera-ting mode of the combustion chamber. That approach will allows, as experimental data accumulate, to formalize objectively this step of the combustion chamber's design process as an additional tool to the Y+ criterion, which is widely used in computational CFD practice. As a modeling environment the authors used ANSYS.Fluent as a CFD environment that has received the greatest distribution due to the successful integration of software and math models in modeling lean burning flows “kerosene + air”. As a CC model, a known stable KS in the cruiser mode, widely used in the educational process, was used.

Keywords:

computational fluid dynamics, non-stationary process, combustion chamber, formal criterion for choosing a turbulence model, stochastic processes

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