Potential flow in engine valves Page: 10 of 29
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N. A.C.A. Technical Memorandum N o. 343
dependence on m. For very small values of K, a is found, by
computing the limiting value for m, to have the value . + 2
This is then manifestly identical with Kirchhoff's case of the
flow from an infinitely long slit.
d) The pressure-loss coefficient = 1 K was also
plotted (Fig. 9). Its curves are very slightly affected by m
and are strongly hyperbolic.
2. Stream free on only one side.- For very small valve-
lifts, as mentioned in the introduction, the experiments showed
a flow, which did not separate at the point E, but was de-
flected 900 (Fig. 10). It was found that, even mathematically,
such a flow exists, which is treated in what follows. The free
surface is assumed to begin at C, whose anzle a' with the x
axis increases to a maximum value a at the point F and then
again in infinity attains the value a' = 0. The question here
is not therefore concerning an entirely free stream, but con-
cerning a stream which is bounded on one side by a fixed wall
and on tre other by a free surface.
The interesting problem now arises as to whether all con-
ditions of flow, which can occur physically in a configuration
like the flat valve have already been exhausted in the fore-
going cases, It is, in fact, possible to carry out an investi-
gation of this kind, which bears principally on the subject of
the log w plane. The hereby mathematically possible cases
are not always physically possible.
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Eck, Bruno. Potential flow in engine valves, report, December 1, 1925; (digital.library.unt.edu/ark:/67531/metadc65148/m1/10/: accessed May 26, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.