基于谐波平衡法的多排叶轮机械非定常反方法研究

Most current turbomachinery aerodynamic design methods are based on steady flow model, however the relative movement between the rotor and the stator in a stage environment determines that the flow in turbomachinery is inherently unsteady. So how to take the unsteady effects into consideration under the design phase is one of the problems pursued by the researchers all the time. In the present project, an attempt is made to combine the advanced unsteady calculation method and the inverse method, so as to formulate an unsteady inverse method and develop an unsteady design system for turbomachines. First an effect integration of the harmonic balance method and the inverse method based on virtual movement is proposed, and the fundamental theory of unsteady design framework can be established. Then loading strategies of time-averaged pressure loading under coupled influences of different unsteady sources will be investigated. Finally according to the so called “wake matching” concept, which can takes upstream and downstream unsteady flow fields in to consideration, an optimized 3D stacking line can be obtained, so that a fully unsteady 3D blade design system can be constructed initially.

目前叶轮机械气动设计方法多基于定常流动模型，而叶轮机械中转子和静子的相对运动决定了其流动为本质非定常的。如何在设计阶段就能将非定常影响纳入考虑，发展非定常设计体系，是研究人员一直试图解决的问题之一。本项目意图结合先进的非定常计算技术和三维粘性反方法，发展成为非定常反方法，建立叶轮机械非定常设计体系。首先申请者提出了基于谐波平衡法和反方法有机集成的思想，并据此建立非定常反方法的基本理论框架；进而分步研究在多种非定常效应影响下时间平均压力载荷的加载策略；最后考虑依据能够考虑上下游非定常流场影响的“尾迹”匹配理念，优化空间积叠线形式，从而构建非定常叶片设计体系。

本项目针对目前在叶轮机械领域缺乏有效的非定常设计工具这个难题，基于谐波平衡法和反方法，开展了三维粘性非定常反方法的研究。首先在已有研发基础上开发了谐波平衡法求解器，且针对动静干涉中的信息传播，发展了完备的交接面处理方法。进而将求解器与三维反方法相结合，即在叶片表面施加时均载荷，通过计算的时均载荷与给定值的偏差来驱动叶片中弧线，实现叶片几何的改变；且在此过程中，叶片厚度不发生变化。然后将所开发工具应用于动静干涉的研究以及多排环境下非定常匹配设计。此外还基于谐波平衡法，验证了时间相关边界条件在单排计算中考虑多排影响的正确性；最后在单排环境下进行了涡轮叶片的积叠线非定常优化。结果发现：（1）传统定常计算和非定常计算对于超声速叶片来说，存在有激波位置波动现象，这表明对于跨声速压气机叶片采用非定常计算来评估激波位置是必须的。（2）通过合理给定载荷，能够降低动静干涉带来的损失，实现比定常反方法更高的效率。这证明了非定常反方法挖掘非定常性能收益的潜力。（3）基于时间相关边界条件和非定常计算方法，开展了某涡轮叶片的积叠线优化研究，使得其损失降低了12%，为实现全三维叶片非定常优化设计积累了经验。