Comprehensive Hydraulic Improvement and Parametric Analysis of a Francis Turbine Runner

Abstract

Hydraulic turbines are usually required to operate in a wide range. The operation at off-design conditions not only reduces the unit efficiency, but also significantly deteriorates the dynamic stability of the turbines. In order to develop a turbine runner with good performances under multi operation conditions, a comprehensive hydraulic improvement has been done of a Francis turbine runner with a multipoint and multi-objective optimization design system. Compared with the initial runner, the runner generated from this method has a satisfactory improvement. In detail, unit efficiencies of the preferred runner are increased by 0.91%, 0.47% and 0.37%, respectively, under the rated head, a high head and the maximum head. The lowest pressure at blade surface is improved by 376.2 kPa under the rated head. CFD calculations are conducted to analyze the flow conditions inside of the preferred runner. In addition, runners with different main design inputs, namely blade lean, blade loading and blade meridional shape are furtherly investigated to reveal their relationship with runner’s internal flow and outer performances. In summary, this optimization system supplies satisfactory results and convincing recommendations to determine the design inputs for low-head Francis turbine runners.

Three-Dimensional Inverse Design Method for Hydraulic Machinery

“…Compared with the conventional design method, which mainly deals with geometrical parameters, fluid dynamic parameters such as pressure or blade loading are considered as the design parameters in the IDM. The fluid dynamic parameters show more direct influence on the hydraulic performance than the geometrical parameters, and it is more convenient to establish a relationship between fluid dynamic design parameters and hydrodynamic performance, which is favorable to the application of a surrogate model, such as the response surface model [56][57][58][59][60][61][62][63][64][65], in the inverse optimization design. At the same time, fewer numbers of fluid dynamic parameters are needed to represent the blade geometry compared to the geometrical parameters, and it is beneficial for the multi-objective optimization design of the hydraulic machinery.…”

Comprehensive Improvement of Mixed-Flow Pump Impeller Based on Multi-Objective Optimization

“…The effectiveness of IDM has been widely proven in the optimization design of various turbomachinery. Zhu et al [15][16][17] improved the efficiency, cavitation and stability performance of a pump-turbine runner by varying the blade loading and stacking by combined using the LHS, RSM, and NSGA-II. Bonaiuti et al [18] increased the high efficiency area of a compressor by changing the blade loading, stacking and spanwise circulation by combined using DOE and RSM.…”

Cavitating Flow Suppression in the Draft Tube of a Cryogenic Turbine Expander through Runner Optimization

“…The optimization strategy usually consists of a runner design method, design of experiment (DOE), CFD analysis, response surface methodology, and multiobjective genetic algorithm method. This strategy was successfully used in the design of a pump-turbine runner [24,25], after the optimization, the performance of the runner was obviously improved. Because of its simplicity, this optimization strategy could be used in the development of fluid machines.…”