离心叶轮非轴对称轮盘面气动敏感性分析

Analysis on Aerodynamic Sensitivity of Non-Axisymmetric Hub of Centrifugal Impeller

为了研究非轴对称轮盘面对高压比离心叶轮的效率、压比、堵塞流量及工况范围的影响规律,采用基于人工神经网络的非轴对称轮盘面全工况预测模型,用于预测30个形状控制参数下轮盘面对气动性能的影响。同时,结合Sobol敏感性分析方法,提取对各性能指标影响显著的敏感参数,研究了敏感参数对于叶轮性能的影响规律。结果表明:轮盘面对效率、压比及堵塞流量的控制主要取决于各个参数独立影响的线性叠加,进口附近轮盘面的凹陷有利于提升最高效率并增大堵塞流量;叶轮出口压力侧分流流道附近的凸起有利于最高效率的提升,但会降低叶轮的压比。不同的是,轮盘面对叶轮工况范围的影响主要源于3个及以上参数的高阶交互作用。利用敏感性分析结果,从经验上人为给定控制参数的取值,实现了离心叶轮非轴对称轮盘面快速优化,在设计点压比不变的情况下,使绝热效率提升了0.9%,工况范围提升了2%,说明敏感性分析可以有效缩短优化周期,从而降低优化成本。该研究结果可为今后的离心叶轮气动设计及优化提供方向性指导。

To explore the influence of the non-axisymmetric hub on the efficiency,pressure ratio,mass-flow of choke and flow range of high-pressure-ratio centrifugal impeller,an artificial neural network(ANN)-based full range prediction model of non-axisymmetric hub is adopted to predict the influence of non-axisymmetric hub on aerodynamic performance under 30 shape control parameters.With Sobol sensitivity analysis method,the sensitive parameters that have significant impact on performance are extracted and studied for their influence on the impeller performance.The results show that the control of the efficiency,pressure ratio and mass-flow of choke by hub surfaces mainly depends on the linear superposition of independent effects of each critical parameter.The concave surface of the hub near the impeller inlet is favorable to improve the maximum efficiency and increase the mass-flow of choke,while the convex surface of the hub near the impeller outlet at the channel of pressure side is conducive to the improvement of the maximum efficiency,but it reduces the pressure ratio of the impeller.In contrast,the influence of the hub deformation on the flow range of the impeller is mainly caused by complex high-order interaction of 3 or more parameters.Based on the results of the sensitivity analysis,the values of the control parameters are manually determined,thereby realizing rapid optimization of the non-axisymmetric hub of the centrifugal impeller,increasing the isentropic efficiency by 0.9%and the flow range by 2%with the designed pressure ratio remaining unchanged.This indicates that the sensitivity analysis effectively shortens the optimization period and reduces optimization costs.This research provides directional guidance for the aerodynamic design and optimization of centrifugal impellers in the future.