Design and Simulation of Two Stroke Engines

Design and Simulation of Two-Stroke Engines
The new purity, Ilci, in the box is found simply as follows:
_ mcnc + dnt - dnE
H Cl (2.18.63)
m Cl
The new properties of the gas in the box after the time step are:
gas constant RC1 = IldR* + (l - ncl)Rexh (2.18.64)
specific heats ratio ycl = nclYair + (1 - ncl)yexh (2.18.65)
From this point it is possible, using the theory given in Sees. 2.18.3 and 2.1.6, to establish
the remaining properties in the box, in particular the reference acoustic velocity, density and
temperature. The connection for the new reference temperature, To, is given by the isentropic
relationship between pressure and temperature as:
T C1 _
To
f \~
PCI
Po )
Yci
C1 (2.18.66)
Consequently the other reference conditions to be employed at the commencement of the
next time step are:
reference acoustic velocity a0 = -y/YciRciTb (2.18.67)
« - PO
reference density Po - ~ — (2.18.68)
K C1 X 0
All of the properties of the gas at the conclusion of a time step, dt, have now been established
at all of the mesh boundaries, in all of the mesh volumes and in all cylinders and
plenums of the engine being modeled. It becomes possible to proceed to the next time step
and continue with the GPB simulation method, replacing all of the "old" values with the
"new" ones acquired during the progress described in entirety in this Sec. 2.18. A new time
step may now commence with all data stores refreshed with the updated numerical information.
Information on the effect of the results of the modeling process of the open cycle and in
all of the ducts may need to be collected. This is discussed in the next section.
2.18.11 Airflow, work, and heat transfer during the modeling process
The modeling of an engine, or the modeling of any device, that inhales and exhales in an
unsteady fashion, is oriented toward the determination of the effect of that unsteady process
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