Design and Simulation of Two Stroke Engines

Chapter 3 - Scavenging the Two-Stroke Engine
Plate 3.4 CAD/CAM techniques at QUB enhance the accuracy of transfer of cylinder
design to experimental scavenging test.
mean? Is it simply the best answer? Is it the best answer in the shortest time or is it simply the
least money expended in the search for the answer. In most realms of R&D activity, money
expended tends to equate with time spent.
While computer technology has provided the CFD theory with which to perform the
theoretical calculations, it has also provided a problem in terms of data preparation prior to
that computation. Fig. 3.20 shows the computation grid required to perform the CFD calculation
for flow from cell to cell within a two-stroke cycle engine cylinder. The computational
meshing procedure is very time consuming; it can occupy several weeks of concentrated
activity by a very experienced programmer. The computation process after that can take days
on a fast computer, perhaps even requiring the use of a supercomputer. Thus, while the ensuing
answer is highly effective and full of information for the designer and the developer, it
takes time and is expensive. What is required to significantly advance the art and science of
CFD is the ability to accurately and rapidly mesh the structure and space being investigated.
275