【作者】 杨玉奇；

【导师】 王仲奇； 王松涛；

【作者基本信息】 哈尔滨工业大学 ， 动力机械及工程， 2010， 硕士

【摘要】 近年来国内外流行的优化设计方法为叶型设计提供了新的思路。优化设计是将叶型的几何形状进行参数化,性能表达成随设计参数而变化的目标函数。设计过程就是根据设计目标函数,选择设计参数使性能最佳,该设计过程是一个自动化过程。本文的工作就是从这一方面着手,将优化理论引入到压气机叶型设计中,建立可用于重型燃气轮机压气机的二维气动优化设计平台。该设计平台在优化设计软件iSIGTH中集成,由自主开发的二维叶型造型程序bladeprofile、网格生成软件AutoGrid5、流场计算分析软件CFX以及后处理软件组成。在优化的过程中,非设计工况和喘振边界是设计的主要目标。所以本优化平台目标函数的选取综合考虑设计点总压损失低,工作范围宽广,喘振边界合理,较小冲角变化时损失低并且变化平稳等因素,进行变工况多目标自动优化设计,以期达到叶型综合性能的改善。在叶轮机械中,转捩对压气机的性能影响较大,主要因为转捩前后的层流边界层和湍流边界层在边界层内的流动结构、流速分布、壁面切应力和换热系数等均不相同,一方面转捩流动的这些特征直接影响着流体机械的动力特性,为了准确的预测流体机械的动力性能,必须明确边界层内流动状态,另一方面通过有效的控制转捩起始点、转捩区长度,可以大大地改善流动效率,提高设计水平。在地面重型燃气轮机的中间和后面级中,雷诺数和来流湍流度都较高,对转捩的起始位置和转捩的发展影响较大,鉴于此在本文的优化设计过程中,应用CFX求解器里的γ-Reθ-方程转捩模型,考虑了地面重型燃气轮机压气机气体在高雷诺数及高湍流度下转捩带来的影响,以使计算结果能够充分的反应叶轮机械内气体的实际流动,从而得到可信的结果。本文以某地面重型燃气轮机压气机第七级静叶中径叶型为研究对象,考虑转捩的影响,应用优化设计平台对叶型进行变工况多目标优化。优化设计后,在叶型负荷高于原型的情况下,目标函数明显降低,在变工况运行条件下,工作范围变得宽广,损失相对于原型有大幅度的降低,且具有一定的喘振裕度。将优化后叶型应用到半叶高直叶片上,使用CFX软件对原始叶片与优化后的叶片进行数值模拟。分别对节距平均参数叶高分布、静叶气动性能进行分析,比较不同叶高处原始叶片与优化叶片的性能。得出设计工况下优化叶片的性能也高于原始叶片。更多还原

【Abstract】 Optimal design method which is popular at home and abroad provides a new way for the blade design. Optimization is parametric the parameters of the blade geometry, and the performance of the blade is expressed as objective function, which changes with the design parameters. Design objective function is designed to select the best design parameters for performance, which is an automated process. From this point the work establishes aerodynamic optimization design platform that is applicable to heavy-duty gas turbine compressor by introducing optimization theory to compressor blade design. The system consists of in-house program for 2D compressor blade design, AutoGrid5 for grid generating, CFX for flow field computation and analysis and in-house codes for optimization. In the optimization process, the off-design condition and the stall margin is the main objection. Therefore, low total pressure loss, wide attainable operating range, reasonable stall margin, low loss at small incidence and stable change are taken into account in the objective function. Multi-objective and mutative condition optimization is established, expecting the improvement of cascade performance.In turbomachinery, transition has a great influence to the performance of compressor, this mainly because the boundary layer, which divided into laminar and turbulent layer, is different in boundary layer structure, velocity distribution, wall shear stress and heat transfer coefficient. On one hand, the transition directly affect the fluid dynamic of machine, in order to accurately predict the dynamic performance of fluid machinery, we must assure the state of boundary layer flow, on the other hand, the efficiency of flow and the level of design can be improved through control the starting point of the transition, the length of the transition zone. In the mid and rear part of the ground-based heavy-duty gas turbine, the high Reynolds Number together with the high turbulence levels have a great influence on the position and the development of transient. In view of this the design process in this paper, applying the one equation model of y-Ree transient model of CFX-solver, considering the influence of transient in high Reynolds and turbulence levels, so that the results of computation can reflect the real flow of turbomachinery, and get reliable results.In this paper, a compressor blade of a ground-based heavy-duty gas turbine has been optimized by the design system referred above. Multi-objective and mutative condition optimization is established, and transition is especially considered in flow field analysis. After optimization, aerodynamic performance of the blade is improved, the trailing edge loss and the total pressure loss are both decreased under this profile. On off-design condition, the work range is larger, the loss is lower to the original profile, and the optimal profile have certain stall margin.The optimized blade profile was applied to each section of the original blade. The three-dimensional numerical simulation is carried on for the original blade profile and the optimized profile with CFX. It shows that the flow angles and static pressure ratios of different blade height are increased, so the performance of optimized blade is much better than the original blade.更多还原