LES of the Exhaust Flow in a Heavy-Duty Engine

Bodin, Olle; Wang, Yue; Mihăescu, Mihai; Fuchs, László

doi:10.2516/ogst/2013117

Cited by 2 publications

(2 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The introduction of time-varying boundary conditions that correctly reflect upstream flow property fluctuations should therefore be favored over routine steady-state CFD. This conclusion is further supported by the fact that complex pipe shapes with bends and curvatures have the potential to generate strong and unsteady secondary flows in hot exhaust flows [17], which necessitate unsteady simulation to correctly assess the interaction with pulsations [18].…”

Section: Discussionmentioning

confidence: 95%

Numerical Assessment of Flow Pulsation Effects on Reactant Conversion in Automotive Monolithic Reactors

2022

View full text Add to dashboard Cite

Highly transient engine-out emissions imply significant challenges for the optimization and control of automotive aftertreatment systems, motivating studies of the effects of flow pulsations on the system behavior. In this work, an axisymmetric aftertreatment system with a first-order reaction in the monolith section is chosen to demonstrate the role of pulsations on the time-averaged conversion at the exit. Reactive computational fluid dynamics simulations under transient conditions are performed by applying the SST k-ω turbulence model along with a reactant species balance equation and a porous medium description of the catalyst. Four different types of temporal velocity variations (constant, step-like, sawtooth and sinusoidal) are applied at the inlet. Additionally, the corresponding fluctuations driven by a prescribed inlet pressure are also investigated. It was found that the fluctuations in the incoming flow affect the transient response of the monolith, the time-averaged conversion, the evolution of the flow uniformity index and the dispersion downstream of the catalyst. It is also shown that the retention time distribution is modulated by the pulsations and that the mixed-cup conversion span is different for geometrically identical systems having the same velocity span if the fluctuation characteristics are different. In conclusion, simulations of phenomena that depend on time-resolved boundary conditions from experiments require proper characterization of fluctuations present in the real-world systems; otherwise, the method of recreating the signal at the boundary may influence the obtained results.

show abstract

Section: Discussionmentioning

confidence: 95%

Numerical Assessment of Flow Pulsation Effects on Reactant Conversion in Automotive Monolithic Reactors

2022

View full text Add to dashboard Cite

show abstract

“…In order to determine the optimal grid the absolute normal deviation P ij , as defined in Bodin et al, 48 of selected flow quantities is considered. The flow case considered is the continuous inflow scenario.…”

Section: Grid Resolution Studymentioning

confidence: 99%

Particle behavior in a turbulent flow within an axially corrugated geometry

Majal

Wittberg

Mihăescu

2021

Advances in Mechanical Engineering

View full text Add to dashboard Cite

In this numerical study particle behavior inside a sinusoidal pipe geometry is analyzed. The 3D geometry consists of three identical modules, with a periodic boundary condition applied to the flow in the stream wise direction. The incompressible, turbulent gas flow is modeled using a Large Eddy Simulation (LES) approach. Furthermore, the particle dynamics are simulated using a Lagrangian point force approach incorporating the Stokes drag and slip correction factor. Four different sizes of particles, corresponding to a Stokes number less than unity, are considered along with two different inflow conditions: continuous and pulsatile. The pulsatile inflow has an associated flow frequency of 80 Hz. The fluid flow through the sinusoidal pipe is characterized by weak flow separation in the expansion zones of the sinusoidal pipe geometry, where induced shear layers and weak recirculation zones are identified. Particle behavior under the two inflow conditions is quantified using particle dispersion, particle residence time, and average radial position of the particle. No discernible difference in the particle behavior is observed between the two inflow conditions. As the observed recirculation zones are weak, the particles are not retained within the cavities for a long duration of time, thereby reducing their likelihood of agglomerating.

show abstract

LES of the Exhaust Flow in a Heavy-Duty Engine

Abstract: and available online here Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 69, n°1, et téléchargeable ici

Cited by 2 publications

References 8 publications

Numerical Assessment of Flow Pulsation Effects on Reactant Conversion in Automotive Monolithic Reactors

Numerical Assessment of Flow Pulsation Effects on Reactant Conversion in Automotive Monolithic Reactors

Particle behavior in a turbulent flow within an axially corrugated geometry

Contact Info

Product

Resources

About