跨声速涡轮叶栅两点优化目标函数研究

Dual Operating Point Optimization Objective Function of Transonic Turbine Cascade

关键词:  涡轮  叶栅  激波  优化设计  目标函数  非设计工况  数值模拟

Key words:  Turbine  Cascade  Shock wave  Optimization design  Objective function  Off-design condition  Numerical simulation

摘要:

针对跨声速涡轮叶栅单点优化方法难以获得整体工况性能提升、多点优化方法难以确定合理目标函数形式的问题，提出了两点优化的方法。为了节约优化时间成本，优化过程采用EIF（Equivalent inviscid flow）模型进行数值模拟，通过添加惩罚函数保证叶栅满足设计流量和负荷要求，并采用叶栅效率线性平均的目标函数形式进行评价。选择两组跨声速涡轮叶栅进行优化设计，并利用CFD方法分析叶型变化对流场马赫数、激波和损失产生的影响。结果显示，所提出的优化设计方法在保证设计工况性能的同时，能够提升叶栅整体工况性能。通过流场分析，揭示了激波结构变化对不同工况损失影响的定性规律。综合全文研究后，给出了一种适用于跨声速涡轮叶栅两点优化设计的目标函数形式。

Abstract:

Considering the difficulty to improve the performance of transonic turbine cascades under whole operating conditions by the single point optimization method， and the problem to determine a reasonable objective function for the multi-point optimization method， a dual point optimization method was proposed. During the process of optimization， the numerical simulation method of EIF （equivalent inviscid flow）model was used to save the optimization time and cost. A penalty function was applied to satisfy the requirements of mass flow and blade load. Meanwhile an objective function of linear averaged cascade efficiency was used to evaluate performance. Two sets of transonic turbine cascades were selected and optimized. And the effects of blade profile changes on Mach number， shock wave and loss were analyzed by using CFD method. Results show that the proposed optimization design method can improve the performance of cascades investigated for whole operating conditions while ensuring the performance at the design condition. The effects of shock wave structure changes on loss at different working conditions were qualitatively studied. Based on the current study， a two-point optimal design objective function suitable for transonic turbine cascades was finally presented.