Regenerative flow pumps, blowers and compressors – A review

This paper presents a detailed and objective review of regenerative flow turbomachines, namely pumps, blowers and compressors. Several aspects of turbomachines like design and operating parameters, working principle, flow behaviour, performance parameters and analytical and Computational Fluid Dynamics (CFD) related details have been reviewed and summarized. Experimental work has been put in perspective and the most useful results for optimized performance have been presented. Consolidated plots of specific speed-specific diameter have been plotted which can be helpful in the early stages of design. Industrial outlook involving details of suppliers from various parts of the world, their product description and applications too are included. Finally, future research work to be carried out to make these machines widespread is suggested. This review is targeted at designer engineers who would need quantitative data to work with.

Investigation of the Matching Relation Between Impeller and Flow Channel of Regenerative Flow Pumps

As a specific radial flow pump, the regenerative flow pump (RFP) usually has a low efficiency. In this study, in order to explore the matching mechanism, three cases with various matching relations were investigated by the methods of theoretical calculation, computational fluids dynamics (CFD) simulation, and experiment test. The results illustrate that the theoretical prediction, numerical simulation and experimental data are in good agreement. Furthermore, when the matching relation expressed by a ratio of the channel's and blade's radial length is equal to 1, the geometrical profiles of RFP can well guide the circulation flow into the channel at large radii and into the impeller at small radii, forming intense longitudinal vortex. The steady, strong exchange flow is characterized by the inflow and outflow regions approximately half of the iso-surface. The axial vortex motion without apparent flow separation and irregular flow is observed in the impeller, a low velocity annulus exists in the medium radii of the impeller without other distinct velocity clouds, and a low velocity strip and a high velocity annulus in the channel are respectively performed along the blade's pressure surface and the channel's outer radii. All of this corresponds to the best pump's performance and the largest efficiency of the impeller and channel. This work promotes a systematical understanding of the matching mechanism between impeller and flow channel in the RFP and could provide some reference for the design and performance optimization for RFP.

Investigation on the Energy Exchange Characteristics of the Regenerative Flow Pump in an Automobile Fuel System

The flow inside the regenerative flow pump (RFP) is quite complex. This study investigated four pump models with various geometrical dimensions to explore the energy exchange characteristics. A computational fluids dynamics (CFD) simulation and the experiment were carried out. The results illustrate that the pressure growth mode in the impeller is consistent with the channels, which confirms the circulation flow existing in the pump. Furthermore, it is found that the circulation flow that features with longitudinal vortexes can be evaluated quantitatively by combining the analyses of the dimensionless axial distance, circulation number and entropy production. A smaller axial distance indicates that more flow is involved in the circulation and the intensity of the longitudinal vortex is enhanced; a large circulation number accompanied by a small dissipation loss could result in a satisfactory exchange flow. Therefore, the largest circulation number, least amount of dissipation, and shortest distance lead to the highest head and efficiency in the model with V-shaped blades and an increased impeller height. This work establishes a deeper understanding of the energy exchange mechanism and could serve as a reference for the geometrical design and performance reinforcement of RFP.

Calculation of flow in incompressible regenerative turbo-machines with bucket form blades based on the geometry of flow path

Purpose Regenerative flow pumps are dynamic machines with the ability to develop high heads at low flow rates. Simplicity, compactness, stable features and low manufacturing costs make them interesting for many applications in industries. The purpose of this study is to present a new method for calculating the flow through regenerative pumps with bucket form blades to predict the performance curves by a cheap and easy-to-use way. Design/methodology/approach The analysis was carried out based on the geometric shape of a fluid particle trajectory in a regenerative turbomachine. The fluid particle path was assumed to be a helix wrapped into a torus. Loss models were considered and the results of predictions were compared with computational fluid dynamics (CFD) data. Findings The overall trend of performance curves resulted from presented model looked consistent with CFD data. However, there were slight differences in high and low flow coefficients. The results showed that the predicted geometric shape of the flow path with the presented model (a helix wrapped into a torus) was not consistent with CFD results at high flow coefficients. Due to the complexity and turbulence of the fluid flow and errors in the calculation of losses, as well as slip factor, there was a discrepancy between the results of the presented model and numerical simulation, especially in high and low flow coefficients. Originality/value The analysis was carried out based on the geometric shape of a fluid particle trajectory in a regenerative turbomachine with bucket form blades. The fluid particle path was assumed to be a helix wrapped into a torus.