Vortex Breakdown Phenomena in a Circular Pipe : 1st Report, Modes of Stationary Breakdown

抄録

The purpose of this investigation is to give a theoretical explanation for the vortex breakdown phenomena of a swirling flow in a pipe. In the proposed mathematical model, the mean flow is assumed to be a rigidly rotating one (constant angular velocity) with uniform axial velocity. It is found that the internal wave (inertial wave), which may occur in the swirling flow, plays a significalt role in the breakdown phenomena. An integer parameter in the formula describing the internal wave, has a close relation with the structural mode of breakdown. Thus, the first three values of the parameter, 0, 1, 2, correspond to the typical three observed types of breakdown, axisymmetric, spiral, and double helix, respectively. The present study concerns only time-independent types of these phenomena. The time-dependent ones will be discussed in another paper.