Design and Simulation of Two Stroke Engines

Design and Simulation of Two-Stroke Engines
DISC
VALVE
PORT
Fig. 5.3 Design dimensions of an intake system disc valve.
As the port corner radii are being uncovered by the edge of the disc, the precise solution
to the geometrical problem is more complex but can be solved with little loss of accuracy by
the iterative approach given above for rectangular ports in Eq. 5.2.1. If xp is considered to be
the port height, after 6° from the opening position:
then
if
Xn = r max 1 min
v = x P - 2r P+ 2 V r P - ° :
e / \
h = n —(rmax + Tmia)
3o(J
(5.2.11)
(5.2.12)
(5.2.13)
where h is the length along the port centerline and is less than the corner radius, rp. The area
of the port during this early stage can be found by the same method given in Eq. 5.2.4, but
with the term for dx/d0 replaced by the following equation, where the angle is expressed in
degrees:
"X _ TtyVnax "*" r minJ
dG " 360
(5.2.14)
A similar iterative approach is employed for the later stages of port opening or closing
when the relevant corner radii are being uncovered or covered, respectively.
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