| Hydraulic energy is a kind of clean, renewable energy. With the rising energy demand and the enhancement of energy saving awareness, development and utilization of small power hydraulic energy will play an important role in the construction of resource-conserving and environment-friendly society. Compared with other types of small power hydraulic energy exploration devices, pumps as turbines (PAT) have the advantages of small, relatively cheap, long service life, easy to manufacture and maintain et al. At present, PATs are mainly used in industrial processes, small hydropower and other field of energy-saving technologies. Research on PATs apparently has social and academic values; therefore PATs are selected as the research topic of this paper. In this paper, study on the selection method of appropriate pumps as turbines, internal flow field analysis, high efficiency design theory and design method, the unsteady flow fields within PAT et al. were performed using theoretical, numerical and experimental analyses. The main work and creative achievements of this paper were:1. The current research status of PAT both at home and abroad was systematically summarized; meanwhile its future development trends were forecasted. The basic theories of PAT were summarized. PAT’s performance characteristics were analyzed. Besides, the relations between the variations of PAT’s performances and their impeller geometric parameters were explored.2. Two types of test rigs namely pump driven by PAT and dynamometer driven by PAT were developed. After experimental research on the two test rigs, the advantages and drawbacks of the two test rigs and other test rigs were found and presented. PAT’s automatic test system software was programmed and the automatic measurement of PAT’s external characteristics was realized.3. Research on the accurate numerical prediction method of PAT’s external performances was performed. Some of the key issues, including three dimensional model simplifications, mesh type and turbulence model selection et al. were studied. Numerical and experimental results showed that PAT’s external performances could be accurately predicted when the complete domain within PAT was modeled, structured grid and standard k-ε turbulence model were selected.4. Numerical and experimental research on both pump and turbine modes of three pumps covering low, medium and high specific speeds were carried out. The differences and correlations between external performances and internal flow fields of the pumps in positive and reverse modes were analyzed. A more accurate half-empirical formula of PAT’s BEP prediction method which could be a helpful guidance in the selection of appropriate pumps as turbines was developed, through detailed investigation into the head and flow conversion factors between pumps and PATs. Besides, hydraulic loss distribution analysis within PATs which could provide a direction for further optimization was performed.5. High efficient impeller design theory and design method of centrifugal PAT was systematically studied for the first time. Impeller main geometric parameters such as blade wrap angle, blade number, blade inlet width, blade inlet angle, blade thickness, splitter blades, impeller diameter, blade swept shape et al. to the influence of PAT’s internal hydraulic loss distributions, internal flow fields and external performances were carried out, therefore the design theory and design method of PAT was enriched. Impeller with forward swept blades which apparently has smaller size and higher efficiency compared with conventional back swept blades was proposed for pump operated in turbine mode only for the first time.6. The high efficiency volute design method of PAT was studied for the first time. Effects of PAT’s volute main geometric parameters such as cross section shape, throat area, spiral development area and volute base circle diameter et al. influencing PAT’s internal hydraulic loss distributions and external performances were acquired through investigations into these geometric parameters to the influence of PAT.7. The unsteady pressure fields within PAT were studied for the first time. Through time domain and frequency domain analyses of the unsteady pressure pulsations within PAT’s main flow components such as volute, impeller and outlet pipe, the unsteady pressure characteristics within PAT were obtained. Effects of blade number, splitter blades and volute base circle diameter influencing PAT’s unsteady flow fields were performed; laws of the above stated parameters to the influence of PAT’s unsteady flow fields were acquired. |
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