THE 'TRONCONICAL' FLOW ― PART ONE DEFINITION, GENERAL FRAMEWORK, NOMENCLATURE, COORDINA IE SYSTEMS

摘要

In the present work, the author introduces a new model of non-conical axisymmetric supersonic flow with compression, called by him "tronconical flow". For the first time mentioned in a Ph.D. thesis, this kind of (low has the peculiarity of achieving the compression by isentropic way (smoothly) and not by shock waves. This results in a series of advantages, both from the viewpoint of the higher values of the compression ratio and from that of the reduced drag put up by the stream at the rated supersonic regime. The idea of the possible existence of such type of axisymmetric supersonic flow emerged as a result of a careful analysis of a schlieren picture from a flow visualizations album. There are presented the general framework, the nomenclature, the coordinate systems that have been used (called by the author "torical", or "tronconical" coordinates), being also deduced the expressions of the radial, normal and circumfe; ential components of the velocity and acceleration vectors, by using the Lame's parameters. The noticeable particular cases of the new flow with isentropic compression arc mentioned, namely the Prandtl-Meyer plane flow and the conical axisymmetric flow inside the first two regions of the Busemann's nozzle (a special axisymmetric nozzle which connects two parallel and uniform supersonic flows). Then, using the same methods as in a previous paper, the author focused his attention on the properties deduced from the equations of motion, as well as from the energy, continuity and velocity potential equations. Possible applications can be found in the experimental aerodynamics (profile of the meridian line for the annular return of some supersonic, axi-symmetric, closed-circuit wind tunnels), in the high-speed aerodynamic design (the shock-free airplane, missile, shell and rocket forebodies and of junction zones between the different diameter cylindrical regions of the multi-stage, supersonic/hypersonic rocket vehicles, as well as that of the frontal and annular shock-free air intakes with dynamic compression of the jet engines, including the ram- and SC-ram jets).