Centrifugal pumps are one of the most widely used machines in all branches of industry. For this reason, their efficiency has a significant impact on energy consumption in global industry (about 20%). It is extremely difficult to design low-specific-speed centrifugal pumps at acceptable efficiency levels due to increasing losses in the impeller (hydraulic, volumetric, and mechanical). This article presents the influence of the geometric features of grooves (width, depth), and the number of them, on the operating parameters of the impeller in a centrifugal pump with microgrooves. The principle of operation of this solution involves the passive control of the flow in the boundary layer using rectangular grooves. The grooves are made inside the flow channels of the impeller and are intended to reduce hydraulic losses occurring during flow. This is mainly due to a reduction in losses in the boundary layer. In order to determine the influence of the grooves’ parameters on the energy characteristics of the impeller, numerical calculations and experimental measurements were performed on 15 sets of impellers, which were obtained using experimental planning methods. The CFD calculations were conducted in order to understand the flow phenomena that occur in the impeller with the microgeometry and their effect on a reduction in internal flow losses. Based on the research results, useful guidelines for designing impellers with low-speed characteristics were formulated.

The article presents results of numerical analyzes, which raise a subject of influence of the cooperation the multi-piped impeller with a rationalized flow geometry of annular casing and volute casing for liquid flow through centrifugal pump and their operating parameters in the extremely low specific speed n_q<10. The multi-piped impeller (patented by authors) is a major alternative to classic vane impellers. The stator type is responsible for the conversion of the kinetic energy of the liquid by the impeller outlet into potential energy, which determines the overall efficiency of the pump. Also, the article presents qualitative and quantitative verification of results obtained by computer modeling and an attempt to estimate their accuracy. The article focuses mainly on the comparison of the performance parameters of the pump with a multi-piped impeller in cooperation with two stator types with a rationalized flow geometry. Both outlet elements were tested in various configurations of constructional features. The complexity of the construction of the stator can significantly affect the manufacturing costs of pump unit. Knowledge concerning construction of hydraulic elements of centrifugal pumps working in the range of parameters corresponding specific speed (n_q<10) is insufficient. As shown in the paper, the annular type casing model pump cooperating with a multi-piped impeller, designed in accordance with literature, reached far poorer operating parameters than the rational annular construction in a configuration with the same impeller.

Centrifugal pumps are one of the most commonly used devices in all branches of industry. Their application area is very broad and practically related to all sectors of the economy. Such pumps are widely applied in the chemicals industry, liquid gas technology, and machine lubrication systems, among others. On the basis of available data, it can be assumed that pumps consume approximately 27% of the world’s electricity. For this reason, their efficiency has a significant impact on the energy consumption of many technological processes. This article presents a summary of the research concerning the cooperation between a multi-piped impeller and a concentric casing. A multi-piped impeller is a completely new concept of a centrifugal impeller, which is characterized by the fact that the energy of the liquid is transferred as a result of the flow of media through the internal flow channels, and also the flow of media around it. The type and design of the casing, with regard to the flow in it and around the impeller’s pipes, plays an extremely important role. Numerical analysis was used as the main research method, which was based on a rotatable experimental plan. The CFD simulation results were validated on a test stand. Finally, the mathematical model and the rules for selecting the geometric features of such a stator were proposed in order to achieve the highest possible efficiency when cooperating with the multi-piped impeller, which constitutes a scientific novelty.

The article presents the results of numerical analyses and experimental research of the influence of various types of stators on a liquid flow through a centrifugal pump with a hole impeller. It is a continuation of authors research of cooperation pump stators with alternative types of impellers which work in ultra low specific speed. Hole impellers have become a significant alternative to classical ones in a range of extremely low specific speed n ^q <10. The aim of the research is to verify the quality as well as quantity of computer modeling results, and to estimate accuracy by examining the impact of a grid and a turbulence model with which the numerical simulations reflect the actual flow.Knowledge concerning construction of hydraulic elements of centrifugal pumps working in the range of parameters corresponding specific speed (n ^q <10) is insufficient. The outlet elements were tested in various configurations of constructional features. The complexity of the construction of the stator can significantly affect the manufacturing costs of pump unit.