As the global environmental protection becomes the world
consensus recently, the regulations of the fuel consumption and the
exhaust gas have large effects on the performance and the
fundamental structure of commercial vehicles. Especially the
technology concerning "fluid" and "heat" has a
close relationship with those issues. Owing to above circumstances,
commercial vehicles such as large trucks and buses are forced to be
designed near the limit of allowance. Furthermore, a rapid design
is another requirement. However, though significant number of
variations, i.e., cab configuration, wheel base, rear body
configuration, engine specification, etc., are prepared, it is
impossible to improve the performance of all those combinations by
experiments which cost a lot. Accordingly, the quantitative
prediction using computer will become indispensable at the
beginning term of new car development.
Then, the authors have completed a new analyzing method to
evaluate aerodynamic drag, engine cooling performance and practical
problem caused by air flow around the vehicle numerically with the
CFD, which will enable to design "well-born" structured
vehicles. For putting this method to practical use, it has been
essential to develop technologies to calculate the flow and thermal
field around the vehicle and in the engine compartment accurately.
This paper introduces outline of those methods.
Finally, it is confirmed that the procedure suggested in this
paper makes it possible to investigate several kinds of performance
concurrently, which are the styling design, the layout in the
engine compartment and the specification of the engine, without
conducting parameter surveys using a prototype vehicle, so that
rapid and optimal development will be available.