1. Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian, Liaoning 116000, China; 2. Department of Engineering Mechanics, Dalian University of Technology, Dalian, Liaoning 116000, China
Abstract：A method for optimizing the hydraulic performance of a mixed-flow pump at multi-operational point was proposed based on surrogate model in this paper to improve the performance under off-design conditions and broaden the flow rate range with a higher efficiency. The initial design of the pump was the hydraulic design made under the design condition, and the initial computational models of the impeller and vaned diffuser were established by parameterrizing their meridional shape and blade angle profile. The poorest efficiency under the part-load, design and over-load conditions was used as the objective function to be maximized and the head at the design point is employed as a constraint. Surrogate models between performance and geometrical variables were generated by using response surface method, and the best combination of these variables was obtained by using CORS-RBF optimization algorithm. According to characteristics of flow in the pump, a two-step optimizationstrategy was proposed, in which the meridional shape and blade angle profile are optimized sequentially to overcome the problem in the whole pump design arose from a large number of design variables and extensive computational cost required.The optimized results show that the pump hydraulic efficiencies were increased by 2.2%, 0.8% and 0.7% under 0.8Qd,1.0Qd and 1.2Qd working conditions, respectively. Additionally, the head satisfies the constraint imposed but also slightly improved. The flow rate range with better pump efficiency is significantly wider in the optimal pump than in the initial design. The relative velocity distribution in the optimal pump is more uniform, showing an obviously optimized effect.
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