Design and Simulation of Two Stroke Engines

Design and Simulation of Two-Stroke Engines
that calculated by a simulation of a racing engine in Fig. 5.35, and to illustrate the point made
above regarding the incorporation of a reed valve model into an engine simulation program, a
few of the results from the experimental and theoretical paper by Fleck et al. [1.13] are presented
here as Figs. 6.24-6.26. The engine used as the research tool in this paper is the highperformance
YPVS RD350LC twin-cylinder Yamaha motorcycle engine, with a peak bmep
of nearly 8 bar at 9000 rpm. Each cylinder has a block holding four reed petals and ports. In
this case, designated as RV1, they are steel reed petals of 0.20 mm thickness, i.e., from Fig.
5.4 the dimension xt is 0.20 mm.
The upper portion of Fig. 6.24 shows the crankcase and inlet port pressure at a "low"
engine speed of 5430 rpm. Those pressure diagrams are predicted by the engine simulation
program and you can see that they are very similar in profile to those observed for the piston
ported engine reported in Chapter 5. In short, there is nothing particularly unusual about the
pressure difference across the reed valve by comparison with that observed for a pistoncontrolled
induction system. The solid line in the lower half of that figure shows the measured
reed tip lift in mm, and that predicted by the reed valve simulation within the computer
program is the dashed line. The close correspondence between the calculation and measure-
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Fig. 6.24 The crankcase and inlet port pressure and reed lift
behavior at a low engine speed.
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