Flow of a Supersonic Gas Jet Emating from a Nozzle Over a Concave Wall
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 6, November, 2020
FLOW OF A SUPERSONIC GAS JET EMATING FROM A NOZZLE OVER A CONCAVE WALL N. I. Sidnyaev
UDC 532.525.2.011.5
The problem on the flow of a supersonic gas jet over a concave wall of any configuration was solved. A method of calculating the gas flow arising as a result of the interaction of a noncalculated supersonic gas jet with a plane wall or a curvilinear one is proposed. Results of measurements of the pressure at the surface of a curvilinear obstacle, over which a supersonic gas jet propagates, and of calculations of the gasdynamic parameters of the gas in the near-wall region of this jet, are presented. The most characteristic regions of a noncalculated supersonic gas jet propagating over a curvilinear reflecting wall, which are of interest for a number of practical applications of such jets and for the constructions of their physical and mathematical models, were determined. The determining parameters of flows in a supersonic gas jet over a concave wall were defined ,and the conductions of their similarity were formulated with regard for the main geometric characteristics of the jet. It is shown that the difference between supersonic gas jets propagating over a curvilinear wall and a plane wall is the pressure difference at their inner and outer boundaries. With the use of formulas of the oblique shock wave theory, the angles of inclination of a noncalculated supersonic gas jet to a concave wall and its gasdynamic parameters in all the regions of the wall were determined. Keywords: noncalculated supersonic jet, concave wall, gasdynamic parameters. Introduction. The interaction of a supersonic gas jet with a curvilinear obstacle takes place in the case of flow of a gas in closed chambers as well as in many technological processes. In the majority of works devoted to the solution of problems on the indicated interaction, the near-wall flows in the supersonic gas jets over plane walls, e.g., the starting shafts of rockets, were considered [1–3]. The problems on the interaction of subsonic and supersonic gas jets with a concave wall remain little investigated because of the complex gas dynamics of the flows arising as a result of this interaction, in which the gas moves with subsonic and supersonic velocities with the formation of compression shocks. In the case where a gas jet with alternating compression shocks propagates over an obstacle, at certain parameters of the jet, in the region of its rotation near the obstacle there can arise nonstationary flows causing an inhomogeneous distribution of the pressure in this region. Because of the complexity of such two-dimensional viscous flows, they, as a rule, are investigated experimentally, and their calculation, performed using semi-empirical methods, allows one to determine the required characteristics of the interaction of the jet with an obstacle on the basis of experimental data on this interaction. However, experimental investigations of the indicated flows are not numerous because
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