РАСЧЁТ КОМБИНИРОВАННОЙ КОНСТРУКЦИИ ЖИДКОСТНОКОЛЬЦЕВОГО ВАКУУМНОГО НАСОСА

Abstract

Liquid ring vacuum pumps are widely used in many areas of the agro-industrial complex, in particular for milking processes, storage of plant materials, their drying and extraction, as well as pneumatic transport. It has been revealed that one of the main disadvantages of liquid ring vacuum pumps - low efficiency (25-50%) is often caused by hydraulic losses during rotation of the liquid ring on a stationary body, as well as inaccurate physical prerequisites in the equations describing the movement of the liquid ring - a two-phase turbulent flow in the working pump cavity. As a consequence, the pump engineering calculation method leads to overestimated performance characteristics at the design stage. In this regard, a combined design of a liquid ring vacuum pump with a rotating casing has been proposed, in which rotation can be transmitted from the impeller blades to the casing blades (in the case of low and medium speed pump size), through involute engagement, or from the casing blades to the impeller blades (in in case of high and especially high speed of action). The basis for calculating the liquid ring is the continuity equation, the stability condition of the liquid ring and the threshold for the occurrence of cavitation phenomena, as well as a coefficient characterizing the drop in speed for turbulent motion in a bladeless space in areas (suction, maximum, compression, discharge). In this case, the mechanism of movement of the liquid ring in the working cavity of the pump is represented by physical processes in the form of the interaction of two power flows: the hydraulic flow of the working fluid and the thermodynamic flow of the gaseous medium. When calculating the main operating parameter of the pump - the actual speed of action - the evaporation of liquid droplets due to changes in the temperature of the liquid ring was taken into account. The forces acting on the rotating wheel and the rotating body of the combined design of a liquid ring vacuum pump are determined analytically.