Cylindrical flow swirler with extended blade chord

Abstract

Introduction. Development of vortex apparatuses — devices for swirling flows of liquids and gases — remains an urgent scientific and engineering task. The design of counter vortex damper flow swirling apparatus at the idle water outlet of Belorechenskaya hydroelectric power plant (HPP) is considered. The purpose of the study is to develop an effective counter vortex damper of excess kinetic energy of water flow. Materials and methods. Analytical methods of classical hydro-mechanics are used. The conceptual basis of the research is the fundamental equality of the geometric characteristic of the vortex apparatus by Abramovich (the Abramovich number) to the Chigier-Beer swirl number. Results. It has been found that geometrical characteristic of the cylindrical vane swirler does not depend on radius of exit edges of blades which swirl the flow, but depends on the angle of bevel of blades at this radius. It allows, according to fundamental equality of Abramovich and Chigier-Beer numbers, either to shift the blades along the swirl chamber radius or to perform them with elongated chord, leaving the hydraulic characteristics of the swirl apparatus and swirled flow unchanged, preserving the bevel angle. Lengthening the chord of the vortex apparatus blades increases the reliability and quality of formation of the swirling flow. It has been proved on the base of differential equation describing the flow lines in the cylindrical swirl chamber that chord of a swirl apparatus prolonged blade flowing smoothly around the flow should have a shape of a logarithmic spiral. It is shown that the vortex apparatus made in the form of a vane system of logarithmic spirals forms a flow with potential rotation superimposed on the potential flow. Conclusions. The design of counter vortex damper of flow energy at the outlet of Belorechenskaya HPP with a system of blades in the form of logarithmic spirals has been analyzed. It is offered to recommend the considered design as a typical one for hydraulic units of medium head.