Numerical investigations of unsteady viscous flow in centrifugal pumps were conducted in this paper. Verification of numerical approach was done. Hydraulic components of the pump were modernized with the purpose to improve their acoustic characteristics. Modernization was held on the base of isotropic turbulence noise measuring techniques. Results were confirmed by experiment. Pressure pulsations were studied in a flow between rotating impeller and stator for initial and improved flowing parts. As a result of numerical research, various impellers with different blade outlet angles were designed. During optimization, the optimal blade outlet angle was found, which provides increased vibroacoustic characteristics while maintaining a high level of efficiency.
The article describes approaches to the design of a vane system of radial-axial hydraulic turbines based on an automated design system developed at SPbPU using the Python programming lan-guage. The specified system currently includes the following modules: selection of the main param-eters of the hydraulic turbine, construction of the meridional projection of the impeller, calculation of the potential flow and construction of the blade system of the radial-axial hydraulic turbine. The choice of the main parameters of the hydraulic turbine is based on the technique generally accepted in hydraulic turbine engineering, which has been digitized and introduced into the software pack-age. The paper considers and analyzes different approaches to the design of the meridional bypasses of the flow path in the area of the impeller of a radial-axial hydraulic turbine, a comparison of the results of their construction using different methods is given. A technique that is most suitable for algorithmization in the software package based on the results of the analysis was selected. The con-struction of streamlines and the calculation of velocities along them are presented on the basis of the calculation of the potential flow in the meridian section. The design of the blade system of the hy-draulic turbine was carried out by the method of solving the direct axisymmetric problem of the theory of hydraulic machines. As an example, a blade system of a radial-axial hydraulic turbine was designed for a head up to 75 meters, the initial parameters of which correspond to hydraulic tur-bines-analogues of similar speed. The designed hydro turbine was calculated in Ansys, and the re-sults confirmed its excellent energy properties. It is planned to further develop the software package in terms of automatic construction of 3-dimensional solid models of the flow path, which can later be calculated by the methods of computational fluid dynamics and optimized to obtain hydraulic turbines with parameters corresponding to the current state of the art.
The issue of ensuring high energy efficiency of high-power pumps is relevant, since an in-crease in hydraulic efficiency of such pump flow parts leads to significant savings in the operation costs. Introduction of digital simulation technologies for the viscous fluid flow makes it possible to optimize geometry of the flow path elements at the design stage and predict pump characteristics with sufficient degree of accuracy. The main elements influencing characteristics of the multi-stage pumps flow parts include impellers and taps. Most often, vane and channel diffusers are used as retractors in the multistage pumps. Results of designing and optimizing flow parts of the low speed multistage centrifugal pump with both types of diffusers are presented, as well as predictive characteristics of pumps obtained using the computational fluid dynamics methods. Hydraulic efficiency of a stage with the channel-type guide (optimized version) is by 0.3 % higher than the efficiency of a stage with the vane-type guide. Both optimized flow paths have a non-sinking nature of pressure characteristics in the low flow region. The pump stage with the channel-type guide has a smaller radial overall dimension than the stage with the vane diffuser = 0.88) and higher design manufacturability. It was found that the most preferable option for the feed electric pump stage with the ns = 85 speed factor is the optimized flow path with the channel-type diffuser
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