| Abstract: | The gas-dynamical structure of jets of a low-density diatomic gas beyond a sonic nozzle at large pressure drops under conditions of a transition from continuous medium processes to rarefied gas processes is examined on the basis of experimental data obtained in low-density gas-dynamical tubes using electron-beam diagnostics and the Pitot tube method. Isomorphism is shown in the density distribution and total pressure in all cross sections of the jet with respect to pressures at a constant value of the complex RL=R*/N1/2(R* is the Reynolds number in the critical cross section of the nozzle, and N is the ratio of the Pitot pressure and the pressure in the discharge chamber). It is shown on the basis of a comparison of local Reynolds numbers for all zones of the jet that this is an analog complex. The experimental data on the variation in the jet structure are presented as a function of the number RL in the range of 5–600. For RL> 100 the flow in the jet can be considered as continuous; for RL< 5–10 the flow corresponds to a scattering process; the range of 5–10< RL< 100 corresponds to a transitional state. Ranges of isomorphism of the jet with respect to R* and N are indicated. Based on the results of the measurements, it is shown that the flow behind a Mach disk for RL> 200 remains subsonic on the axis to a distance of several lengths of the primary cycle. A transition to supersonic velocity on the jet axis can occur with a decrease in the numbers RL owing to ejection acceleration by the supersonic ring-shaped compressed layer.This word is apparently interchangeable with  self-similarity -Translator.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 64–73, March–April, 1973. |
