Multiphase pumps for offshore plants must perform at high pressure because they are installed on deep-sea floors to pressurize and transfer crude oil in oil wells. As the power for operating pumps should be supplied to deep sea floors using umbilicals, risers, and flow lines (URF), which involve a higher cost to operate pumps, the improvement of pump efficiency is strongly emphasized. In this study, a design optimization to improve the hydrodynamic performance of multiphase pumps for offshore plants was implemented. The design of experiment (DOE) techniques was used for organized design optimization. When DOE was performed, the performance of each test set was evaluated using the verified numerical analysis. In this way, the efficiency of the optimization was improved to save time and cost. The degree to which each design variable affects pump performance was evaluated using fractional factorial design, so that the design variables having a strong effect were selected based on the result. Finally, the optimized model indicating a higher performance level than the base model was generated by design optimization using the response surface method (RSM). How the performance was improved was also analyzed by comparing the internal flow fields of the base model with the optimized model. It was found that the nonuniform flow components observed on the base model were sharply suppressed in the optimized model. In addition, due to the increase of the pressure performance of the optimized model, the volume of air was reduced; therefore, the optimized model showed less energy loss than the base model.

On the basis of the momentum exchange theory, an improved mathematical model is developed to analyse the complicated helical flow in regenerative turbomachines and to suggest a systematic way to design such kind of machines. The helical flow in the machines is resolved into a peripheral component and a circulatory component, and a theoretically sound method is proposed to calculate the circulatory flow velocity and slip factor, which are closely related to the machine performance. To implement the present method, the concepts of a circulatory pivot and an effectiveness of the circulatory flow are introduced. The circulatory flow loss was successfully estimated by introducing a bend-combination factor by adding four right angle bends losses. It was found that the overall head rise and the hydraulic efficiency can be accurately predicted by the proposed model equation and the present loss models. Development of the static pressure along the peripheral direction could be predicted satisfactorily.

The regenerative pump is a kind of turbomachine that is capable of developing a high pressure rise at relatively low flow rates compared to the centrifugal and axial pumps. Although the efficiency of regenerative pumps is much lower than other turbomachines, they have still been widely used in many industrial applications for high heads at low flow rates. There are a few theoretical models to analyze the performance of regenerative pumps, though, the effect of the blade angle has not been included in any analysis model to date. In this study, the influence of the impeller blade angle and its shape on regenerative pump performance has been experimentally investigated. Straight blades with inclined blade angles of 0°, ± 15°, ± 30° and ± 45° were tested. In addition radial chevron impellers with chevron angles of 15°, 30° and 45° were also included in the present experiments. Hence a total of 10 blade configurations were examined. The pressure head, efficiency and the fluid temperature rise were measured at different flow rates and the results were expressed in appropriate non-dimensional coefficients. From the experimental results, it was found that the pressure head and the efficiency strongly depend on the blade angles as well as the blade geometry. Among all blade configurations tested in this study, the chevron blade exhibited the highest head with reasonably good efficiency. The comparative study shows that there is an optimum chevron angle of around 30° that yields the best performance. These experimental data may be used to include the effect of blade angles in the current performance analysis and design models to widen their applicability.

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The present study is focused on the design of a regenerative flow pump for artificial heart pump application and the experimental testing and results. It is based on the improved momentum exchange theory proposed by Yoo et al. [1]. Salient feature of the present design procedure is that it does not require any re-adjustment of the input data. Using the design procedure, a regenerative flow type blood pump has been designed and manufactured to confirm its validity.