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Automatic Geometry Optimization of Exhaust Systems Based on Sensitivities Computed by a Continuous Adjoint CFD Method in OpenFOAM
Technical Paper
2010-01-1278
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Meeting backpressure and flow uniformity requirements within
severe packaging constraints presents a particular challenge in the
layout of catalyst inlet cones. In these cases, a parameterized
optimization of the potentially complex cone geometries is
inefficient (and inappropriate). Even assuming that a
parameterization of the complex surface forms is possible, the
choice of parametric shapes invariably affects the achievable
results. Additionally, the long computation time for solving the
flow fields limits the number of shape parameters that can be
considered.
To overcome these restrictions, an optimization tool has been
developed at EMCON Technologies that is based on the continuous
adjoint method (augmented Lagrange method) of Othmer et al. The
open source CFD toolbox OpenFOAM® is used as the platform for the
implementation. Since the geometry itself is modeled using an
immersed boundary method (in which finite volume cells are marked
as fluid or solid), no geometry parameterization is required. The
method allows computation of the sensitivity of flow uniformity and
energy dissipation (or other target quantities) based on the
instantaneous geometry. After the calculated surface sensitivities
are combined and corrected for manufacturing and topological
constraints, the location of the immersed boundary is automatically
adjusted. It is thus possible to automatically determine a feasible
catalyst cone geometry starting from an amorphous box (representing
the packaging constraints) that is supplemented by definitions of
inflow boundaries (for the flow coming from different manifold
runners) and the outflow boundary (the catalyst surface). The
calculation time associated with the process is on the same order
of magnitude as the solution of the RANS equations itself. The
optimization tool, its theoretical basis and some practical results
are presented in the paper.
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Authors
Citation
Hinterberger, C. and Olesen, M., "Automatic Geometry Optimization of Exhaust Systems Based on Sensitivities Computed by a Continuous Adjoint CFD Method in OpenFOAM," SAE Technical Paper 2010-01-1278, 2010, https://doi.org/10.4271/2010-01-1278.Also In
References
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