The horizontal exhaust in trucks is preferred over the vertical exhaust stack
since the cost of production is lower than that of the vertical stack. The
horizontal exhaust also comes with lower fuel costs since the overall drag
coefficient is lower than that of the vertical stack. However, since a
horizontal exhaust exits into the underbody, it is essential to minimize the
exit temperatures of the exhaust to keep component temperatures within design
limits.
In this study, a shape optimization is executed for the exhaust tip geometry to
reduce exhaust exit temperatures while maintaining exhaust pressure by employing
a computational fluid dynamics (CFD) workflow, using the geometry and morphing
tool PowerDELTA®, coupled simulation approach between PowerFLOW® the flow solver
and PowerTHERM® the thermal solver and Isight® for executing the optimization
objectives.
A good correlation is observed with experimental data for the baseline truck
design. The optimization process significantly reduced the exit temperatures of
the exhaust. The optimal design performance was confirmed by installing the
optimized exhaust geometry to the full vehicle, running the full-vehicle
simulation, and observing a similar reduction in the exit temperature of the
exhaust.