| Abstract: | The structure of planar and axially symmetric configurations which, by satisfying a number of geometrical constraints, are circumvented in a boundless space or in a cylindrical channel by an ideal (non-viscous and non-thermally conducting) gas with a maximal critical Mach number M* is found. The analysis is carried out using the “rectilinearity property” of a sonic line in “subsonic” flows (SF), the “principle of a maximum” for an SF and “comparison theorems” which are either taken from /1/ or serve as a generalization of the corresponding assertions from /1/. Following /1/, configurations are considered which have a plane or axis of symmetry parallel to the velocity V∞ of the approach stream, while flows in which (including the boundary) the Mach number M  1 are said to be “subsonic”. As usual, by M* we mean a value of M∞ such that the inequality M1, which is satisfied in the whole stream when M∞ M*, is violated when M∞>M*.The configurations investigated include closed bodies and the leading (trailing) parts of a semi-infinite plate or a circular cylinder in an unbounded flow and in a channel as well as lattices of symmetric profiles. Both in /1/, where the structure of closed planar and axially symmetric bodies was found, as well as in /2/, where such bodies were constructed numerically, the generatrices of all the configurations investigated contain the end planes or the segments replacing them of the maximum permissible slope (in modulus) and the “free” streamlines with M  1. Now, however, unlike in /1, 2/, segments of the horizontals are added to it in the general case. Furthermore, in the case of flows in channels and lattices, the configurations which have been found can be circumvented with the development of finite domains of advancing sonic flow. |
