Influence of Different Subgrid Scale Models in LES of Supersonic Jet Flows

Abstract

Current design constraints have encouraged the studies of aeroacoustics fields around compressible jet flows. The present work addresses the numerical study of subgrid scale modeling for unsteady turbulent jet flows as a preliminary step for future aeroacoustic analyses of main engine rocket plumes. An in-house large eddy simulation (LES) tool is developed in order to reproduce high fidelity results of compressible jet flows. In the present study, perfectly expanded jets are considered because the authors want to emphasize the effects of the jet mixing phenomena. The large eddy simulation formulation is written using the finite difference approach, with an explicit time integration and using a second order spatial discretization. The energy equation is carefully discretized in order to model the energy equation of the filtered Navier-Stokes formulation. The classical Smagorinsky model, the dynamic Smagorinsky model and the Vreman models are the chosen subgrid scale closures for the present work. Numerical simulations of perfectly expanded jets are performed and compared with the literature in order to validate and compare the performance of each subgrid closure in the solver.

A Comparison of Low and High-Order Methods for the Simulation of Supersonic Jet Flows

“…and P r SGS is the SGS Prandtl number. The work of Junqueira-Junior et al (2018) compares the effects of different SGS models on the simulations of jet flows, and it observes a weak influence of the models. Therefore, the present work only applies the static Smagorinsky model (Smagorinsky, 1964) in order to calculate the subgrid-scale contribution.…”

“…In the present work, the authors decided to utilize the geometry that provided the best results in the work of Junqueira-Junior et al (2018). Such a configuration has a divergent shape with an axis length of 40D.…”

“…The present calculations apply the same boundary conditions of Junqueira-Junior et al (2018) for the sake of consistency. For the jet inlet boundary condition, the red region in Fig.…”

“…In the FLEXI simulations, the data are stored with a frequency of 100 kHz, which is at least 4 times larger than the acquisition frequency from the experiments. From the work of Junqueira-Junior et al (2018), the data from the simulation using JAZzY are stored with a frequency of 280 kHz.…”

“…A compressible LES tool, JAZzY, was specifically designed to generate unsteady flow data of compressible turbulent jets based on a second-order spatially accurate method for structured grids. A validation of JAZzY is performed in Junqueira-Junior et al (2018) for a supersonic jet flow configuration. The validation results indicate a shorter potential core of the jet when compared to experimental and numerical data.…”