Potential flow in engine valves Page: 17 of 29
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N.A.C.A. Technical Memorandum No. 343
200, since, from there down, a term appears which was neglected
in the calculation.
It is easily seen that the flow in the limiting cases is
in order. For large overlappings the angle is very small and
finally becomes a = 900, at m = . At m = 1 (i-.e., in the
case where the channel is wide open), it is easily seen from
the equations for m, that K = 1 and a = 900. In constant
overlappings, K also increases with increasing a, so that
a reaches its apparent maximum at K = 1. For positive over-
lappings, the matnum angle is amax = 140 in case IIb and
amax = 8o in IIa. Each overlapping attains a maximum angle
at K = 1.
The course of rn with negative overlapping is quite dif-
ferent from what it is with positive overlappings. The indi-
vidual curves alternately cross one another so that, with in-
creasing K, a first increases, reaches a maximum and then
sinks again to K = 1. As to whether such a flow actually ex-
ists, cannot be maintained without further investigation.
Since this somewhat resembles the behavior of a throttle valve,
but does not concern valve flows, it was not investigated
In what follows, the quantities in question were determined
for several overlappings. Since the valves in use show over-
lappings of m = 0-0.6, there were investigated: mn = 0; 0.05;
0.1; 0.2; 0.3; 0.6. The corresponding values of K, a, etc.,
are obtained in the following manner. In the m diagram, for
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Eck, Bruno. Potential flow in engine valves, report, December 1, 1925; (digital.library.unt.edu/ark:/67531/metadc65148/m1/17/: accessed March 30, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.