| dc.description |
The non-equilibrium supersonic flow of a relaxing or reacting
gas through a plane expansion has been studied from a numerical,,
analytical and experimental point of view.
The flow of an ideal dissociating gas in a two dimensional
expansion has been solved numerically by writing the governing
equations of motion in their characteristic form.
In conflict with linearised theory along the wall, the
numerical solutions do not asymptote to the infinite rate equilibrium
values. To estimate how far the asymptotic state deviates from the
infinite rate equilibrium values, a formal second order solution has
been developed with the aid of transform techniques. An example has
been discussed for a simplified relaxing gas model, and estimates of
the asymptotic state have been obtained. An exact solution over the
whole field was not possible but by treating the parameter
as small, an approximate answer has been found.
To understand in more detail the coupling effects of two
relaxation processes, linearised theory has been extended to cope
with the flow of a gas with more than one relaxing mode. An example
has been discussed far Carbon Dioxide and the effect of possible
coupling between the bending and stretching modes of the molecule
in a plane expansion has been investigated.
The Mach-Zehnder interferometer and Schlieren method have
been used in conjunction with a 2" - diameter shock tube to study the
density and density gradients within, and following a sharp two-dimensional
expansion for shock heated Carbon Dioxide. Measurement
of the density gradient at the leading edge of the expansion by
quantitative Schlieren methods have allowed relaxation times to be
obtained. This method has the advantage that relaxation times can
be obtained for specific values of the density and temperature for
only small departures from an equilibrium state. |
|