Abstract
Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) are performed of a round fluid jet entering a high-pressure chamber. The chemical compositions and temperatures of the jet and that of the fluid in the chamber are initially prescribed. The governing equations consist of the conservation equations for mass, momentum, species and energy, and are complemented by a real-gas equation of state. The fluxes of species and heat are written in the framework of fluctuation-dissipation theory and include Soret and Dufour effects. For more than two species, the full mass diffusion and thermal diffusion matrices are computed using high-pressure mixing rules which utilize as building blocks the corresponding binary diffusion coefficients. The mixture viscosity and thermal conductivity are computed using standard mixing rules and corresponding states theory. To evaluate the physical model and numerical method, LES is employed first to simulate a supercritical N2 jet injected into N2. Time averaged results show reasonable agreement with the experimental data. Then, DNS is conducted to study the spatial evolution of a supercritical N2 jet injected into CO2. Time averaged results are used to compute the length of the potential core and the species diffusion characteristics. Spectral analysis is then applied on a time series data obtained at several axial locations and a dominant frequency is observed inside the potential core.
Highlights
Numerous propulsion devices - diesel, rocket, gas turbine and HCCI engines - rely on mixing and combustion of chemical species under high-pressure conditions
Zong et al [25] performed two-dimensional jet simulations and compared the radial variation of the density pro...le at two axial locations to the experimental data of Chehroudi et al [26]; the agreement with the experimental data was reasonable despite the lack of portraying stretching/tilting e¤ects which are typically considered important in vorticity production
Large Eddy Simulation (LES) is ...rst used to evaluate the physical model and numerical method for a cryogenic N2 jet injected into a N2-...lled chamber
Summary
Numerous propulsion devices - diesel, rocket, gas turbine and HCCI engines - rely on mixing and combustion of chemical species under high-pressure conditions. We conduct both LES to evaluate the model by comparison with experimental data and DNS to understand the details of ‡ow evolution in a spatial con...guration rather than the temporal con...guration of the past [12].
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