Research of the torque-flow pump operating process with a non-cyclic impeller in the operating range

Abstract

Torque-flow (TFP) pumps are widely used in various industries for pumping contaminated, fibrous or gas-containing liquids due to their simple design, reliability and low risk of clogging, despite the limitations of efficiency and head. The main disadvantages of torque-flow pumps are low energy efficiency (pump efficiency η=0.38-0.58) and the possibility of clogging of their flow part by the pumped product. This problem can be solved by ensuring the self-cleaning effect of the torque-flow pump by designing the impeller with a non-cyclic arrangement of blades, which will ensure a pulsating nature of the pressure in its inter-blade channels. The aim of the study was to establish the characteristics of a pump with non cyclic arranged blades and compare the results obtained with the characteristics of a similar pump with evenly arranged blades. To conduct a numerical research in the ICEM CFD software package, unstructured computational meshes of the stator element (housing) and the rotor element (impeller) were created. The pump operating process was simulated in a stationary setting using the Ansys CFX software package, and the k-ε turbulence model in a stationary setting was used, water at a temperature of 25°C was used as the operating medium. According to the results of the study, it was found that when using an impeller with a non-cyclic arrangement of blades (with no blades), there is an increase in the relative velocity near the operating side of the blade in the expanded inter-blade channel, an uneven distribution of relative velocity at the entrance to the wheel simultaneously with the appearance of a flow separation zone in the inter-blade channels, which leads to increased losses, reduced pressure and, accordingly, pump efficiency. At the same time, the above allows us to state that according to Bernoulli's law, there is some increased pressure in the expanded impeller channels with a non-cyclic arrangement of blades in the reduced speed zones. This increased pressure creates the prerequisites for unstable relative motion of the operating fluid compared to using a standard impeller. In turn, this mechanism can be used as a self-cleaning mechanism for torque-flow pumps.