基于代理模型的混流泵多工况水力性能优化设计

Surrogate model-based optimization design of hydraulic performance of mixed-flow pump at multi-operational point

为了拓宽混流泵高效区的运行范围,提高泵非设计工况下的水力性能,提出基于代理模型的混流泵多工况水力性能优化方法.由设计工况单点水力设计得到泵初始设计,并通过叶轮、导叶的参数化方法建立初始计算模型.以叶轮和导叶子午面形状参数以及叶片安放角为优化参数,设计工况下的扬程为约束条件,小流量工况、设计工况、大流量工况下最小效率最大化为优化目标.通过RBF代理型方法建立性能指标与优化参数之间的近似模型,利用CORS优化算法对近似模型进行寻优.根据泵流动特性,提出对子午面形状和叶片形状分步优化策略,有效解决了泵整机模型设计参数多、计算量大的问题.优化结果表明:在0. 8Qd,1. 0Qd,1. 2Qd工况下,泵水力效率分别提高了2. 2%,0. 8%和0. 7%,扬程均满足约束条件并稍有提高,泵效率曲线较初始设计明显变宽;泵内流场速度分布更加均匀,优化效果明显.

A method for optimizing the hydraulic performance of a mixed-flow pump at multi-operational point was proposed based on surrogate model 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 parameterizing 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 was 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 optimization strategy was proposed,in which the meridional shape and blade angle profile were 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 are 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 and is 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.