Passive and Active Control of Supersonic Axisymmetric Base Flows: Direct Numerical Simulations and Large-Eddy Simulations

2002 ◽  
Author(s):  
Hermann F. Fasel
Keyword(s):  
Numerical Simulations ◽  
Active Control ◽  
Direct Numerical Simulations ◽  
Large Eddy Simulations ◽  
Large Eddy ◽  
Base Flows

Numerical Simulation of Free-Surface Turbulence

1994 ◽  
Vol 47 (6S) ◽  
pp. S163-S165
Author(s):  
Douglas G. Dommermuth ◽  
Rebecca C. Y. Mui
Keyword(s):  
Numerical Simulation ◽  
Numerical Modeling ◽  
Free Surface ◽  
Numerical Simulations ◽  
Free Surface Flows ◽  
Direct Numerical Simulations ◽  
Large Eddy Simulations ◽  
Surface Flows ◽  
Large Eddy ◽  
Free Surface Turbulence

Direct numerical simulations and large-eddy simulations of turbulent free-surface flows are currently being performed to investigate the roughening of the surface, and the scattering, radiation, and dissipation of waves by turbulence. The numerical simulation of turbulent free-surface flows is briefly reviewed. The numerical, modeling, and hardware issues are discussed.

Assessment of the validity of RANS knock prediction using the resonance theory

2019 ◽  
Vol 21 (4) ◽  
pp. 610-621 ◽  
Author(s):  
Corinna Netzer ◽  
Lars Seidel ◽  
Frédéric Ravet ◽  
Fabian Mauss
Keyword(s):  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Large Eddy Simulations ◽  
Navier Stokes ◽  
Post Processing ◽  
Resonance Theory ◽  
Auto Ignition ◽  
Engine Knock ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes

Following the resonance theory by Bradley and co-workers, engine knock is a consequence of an auto-ignition in the developing detonation regime. Their detonation diagram was developed using direct numerical simulations and was applied in the literature to engine knock assessment using large eddy simulations. In this work, it is analyzed if the detonation diagram can be applied for post-processing and evaluation of predicted auto-ignitions in Reynolds-averaged Navier–Stokes simulations even though the Reynolds-averaged Navier–Stokes approach cannot resolve the fine structures resolved in direct numerical simulations and large eddy simulations that lead to the prediction of a developing detonation. For this purpose, an engine operating point at the knock limit spark advance is simulated using Reynolds-averaged Navier–Stokes and large eddy simulations. The combustion is predicted using the G-equation and the well-stirred reactor model in the unburnt gases based on a detailed gasoline surrogate reaction scheme. All the predicted ignition kernels are evaluated using the resonance theory in a post-processing step. According to the different turbulence models, the predicted pressure rise rates and gradients differ. However, the predicted ignition kernel sizes and imposed gas velocities by the auto-ignition event are similar, which suggests that the auto-ignitions predicted by Reynolds-averaged Navier–Stokes simulations can be given a meaningful interpretation within the detonation diagram.

Numerical Modeling of Soot Production in Aero-Engine Combustors Using Large Eddy Simulations

2015 ◽  
Author(s):  
B. Franzelli ◽  
E. Riber ◽  
B. Cuenot ◽  
M. Ihme
Keyword(s):  
Numerical Simulations ◽  
Flame Structure ◽  
Precursor Chemistry ◽  
Turbulent Flames ◽  
Large Eddy Simulations ◽  
Reduced Chemistry ◽  
Tabulated Chemistry ◽  
Large Eddy ◽  
Aero Engine ◽  
Aero Engines

Numerical simulations are regarded as an essential tool for improving the design of combustion systems since they can provide information that is complementary to experiments. However, although numerical simulations have already been successfully applied to the prediction of temperature and species concentration in turbulent flames, the production of soot is far from being conclusive due to the complexity of the processes involved in soot production. In this context, first Large Eddy Simulations (LES) of soot production in turbulent flames are reported in the literature in laboratory-scale configurations, thereby confirming the feasibility of the approach. However numerous modeling and numerical issues have not been completely solved. Moreover, validation of the models through comparisons with measurements in realistic complex flows typical of aero-engines is still rare. This work therefore proposes to evaluate the LES approach for the prediction of soot production in an experimental swirl-stabilized non-premixed ethylene/air aero-engine combustor, for which soot and flame data are available. Two simulations are carried out using a two-equation soot model to compare the performance of a hybrid chemical description (reduced chemistry for the flame structure/tabulated chemistry for soot precursor chemistry) to a classical full tabulation method. Discrepancies of soot concentration between the two LES calculations will be analyzed and the sensitivity to the chemical models will be investigated.

Large-Eddy and Direct Numerical Simulations of the Bachalo-Johnson Flow with Shock-Induced Separation

2017 ◽  
Vol 99 (3-4) ◽  
pp. 865-885 ◽  
Author(s):  
Philippe R. Spalart ◽  
Kirill V. Belyaev ◽  
Andrey V. Garbaruk ◽  
Mikhail L. Shur ◽  
Mikhail Kh. Strelets ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Large Eddy
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