Movable blade systems of low specific speed centrifugal pumps

Abstract

One of the most common types of pumping units used in industry are centrifugal pumps. In turn, there is a classification of centrifugal pumps according to design features. So-called low specific speed pumps are designed for low flow and high pressure. This type of pump is widely used in the chemical and oil industries due to its operating conditions, which involve overcoming the resistance of long technological pipelines. At the same time, low specific speed centrifugal pumps have low energy efficiency due to extensive vortex formation the moving fluid inside the flow area. In order to increase the energy efficiency of low specific speed pumps, a new approach to the design of the main operational entity of the centrifugal pumps. The identity of the approach lies in the use of a movable blade system in low specific speed centrifugal impellers. The geometry of their meridian projection, peculiar only to low specific speed impellers, has been adapted to the possibility of rotating each separate blade relative to its axis of rotation. The mobility of the blades will allow to influence the hydrodynamics not only in the impeller by changing the width of the inter-blade channel and the blade angles at the blades at the inlet and outlet, but also, as a result, in the volute, which will lead to greater coherence of their flow modes. Numerical calculations showed that the proposed approach is able to change the work characteristics of a centrifugal pump by reducing its power consumption over the entire operating range, which can be considered as an increase in the energy efficiency of the pumping unit.