Abstracts

Russian participants

The problems of near- and transonic gasdynamics of ideal (inviscous and nonconducted) gas are considered. The simple method of analysis of special features of piece-potential two-dimensional streams is given for the nearsonic flows with a maximum Mach number M = 1. In particular, it allows to study the flow near a sonic line. The structure of the shockless separated overflow of a finite wedge by a sonic jet with an infinite width is studied. The unseparated overflow around a finite profile is described when supersonic zones are formed and extended till the jet’s boundaries. The results are presented for shocks closing the local supersonic zones (LSZ), for features of the transonic streams accelerating from an axis of symmetry, and for diffraction of weak shocks on the wedge under conditions of "Neuman’s paradox". The role of sonic streamlines being parts of a boundary extremum is marked for problems of maximum thrust contours design with big angles of the stream turning. The simple method of constructing the supercritical profiles with shockless deceleration of supersonic flow in LSZ is supposed. It is based on the introducing (for an intermediate stage) "composite" gas (CG). CG is identical to "normal gas" (for example to perfect gas) when pressure p is greater than critical p*. When p < p* then normal gas is replaced by "anormal gas" with a negative fundamental derivative (second derivative of specific volume with respect to p for a constant entropy). In the anormal (opposite to normal) gas the compression shocks are impossible, whereas the rarefaction shocks are possible. The final result of the supercritical profile design is not restricted by using CG in the intermediate stage. In connection with using CG in computations by Godunov-like schemes the problem of arbitrary discontinuity decay is solved when one of the waves is started (finished) in normal (anormal) gas or on the contrary. The interesting feature of such waves is the flow velocity normal to the shock to be equal to a velocity of sound not only behind the shock (as in Chapman’s detonation), but also before it.

Note. Abstracts are published in author's edition

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