Comparison of various turbulence models for ejector nozzle CFD

Ruslan Tsukanov

Abstract


The subject of this article is the application of various turbulence models to calculations of thrust-augmenting ejector nozzles for jet engines by computational fluid dynamics (CFD). The goal is to justify the selection of the turbulence model in CFD-calculations of thrust-augmenting ejector nozzles. The tasks addressed include: searching for and analyzing information sources as for application of different turbulence models in CFD-calculations of thrust-augmenting ejector nozzles; selecting a reliable and complete source of experimental data for digital simulation; constructing an axisymmetric model of the ejector nozzle and three meshes (coarse, medium, and fine); establishing boundary conditions; estimating of uncertainty due to discretization using Grid Convergence Index – GCI; verifying mesh independence; validating the calculation model’s accuracy; performing calculations using fourteen turbulence models; determining the accuracy ranking of these turbulence models; and formulating recommendations regarding the application of the turbulence models for these problems. The methods employed include: a search of relevant information sources on the Internet and analysis based on operational experience in the aviation sector; the method of computational fluid dynamics; digital calculation of Grid Convergence Index; and errors analysis. The following results were obtained: based on the analyzed information sources, it was found that the majority of authors of available studies, devoted to thrust-augmenting ejector nozzle, use different versions of k‑e and k‑w turbulence models. Based on the data from NASA memorandum, a computational model of ejector nozzle was constructed; and its accuracy was validated by three different methods (using GCI, by comparing the static pressure distribution along the nozzle shroud, and by comparing the nozzle integral parameters). This model of ejector nozzle was applied to calculations using fourteen turbulence models. Through comparison with NASA, experimental data and multi-criteria expert analysis of the obtained results, the best three turbulence models yielding the lowest errors (in static pressure distribution along the nozzle shroud, and in calculations of the nozzle integral parameters) were identified. Conclusions. The scientific novelty of the results obtained lies in the following: based on a comparison of numerical simulation results of the ejector nozzle using fourteen turbulence models with NASA experimental data, three turbulence models demonstrating the lowest errors rates were identified and recommended for calculating thrust-augmenting ejector nozzles. Thus, turbulence models suitable for the development of a design methodology for thrust-augmenting ejector nozzles for micro-turbojets were identified. The goals and challenges of the following research in this field are outlined.

Keywords


gas-turbine engine; thrust augmenting ejector nozzle; thrust augmentation; entrainment ratio; primary nozzle; ejector mixing chamber

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References


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DOI: https://doi.org/10.32620/aktt.2026.1.01