Plane-parallel and axisymmetric flows with a straight sonic line

Features of plane-parallel and axisymmetric flows of an ideal (inviscid and non-heat-conducting) gas with a straight sonic line are studied. The flows under study occur in symmetric and asymmetric plane nozzles and axisymmetric nozzles with circular and annular cross sections. The acceleration and deceleration of flows when a straight sonic line is approached or receded from are studied. Additionally, sonic streamlines are constructed, including a contour of a sonic central body, i.e., a sonic streamline starting at the point of a straight sonic line on the axis of symmetry. The capabilities of the developed approaches are illustrated by examples, which are of interest in themselves.