Design and Simulation of Two Stroke Engines

Chapter 2 - Gas Flow through Two-Stroke Engines
These simultaneous equations can be solved for the unknown quantities, Xp and Xq, after
further collections of known terms within FR and FL are made for simplification:
The final outcome is that:
G4
1
F-° 6+ I
b L ~ —~
1 + D + FL + FLC
P = G4(FRFL -1) < 2 - 18 - 18 )
1 + C + FR+F^D
q ~ G4(FRFL - 1) ( 2 - 18 - 19 )
Thus, assuming that the value of wave pressure is going to be modified by friction or area
change during its travel during the time step, the new values of leftward and rightward wave
pressures at the left- and right-hand ends of mesh J, Xp and Xq, at the conclusion of the time
step, dt, are going to be given by:
XRinew = Xp + {+ friction effects (±) area change effects} (2.18.20)
XLnew = Xq + {± friction effects (±) area change effects} (2.18.21)
Each particle within the mesh space is assumed to experience this superposition process
involving the pressure waves, pp and pq. Consequently the new values of the unsteady gasdynamic
parameters attributed to the particles undergoing this superposition effect are:
pressure amplitude ratio Xs = Xp + Xq - 1 (2.18.22)
pressure ps = p0xf 7 (2.18.23)
density ps = p0X? 5 (2.18.24)
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