基于近壁面二次流修正方法的高负荷轴流压气机吸力面-端面造型反设计研究

The development of high-performance aero-engines require compressors to be designed with higher load. However, because of the serious end wall problem, the overall efficiency and stall margin will be significantly deteriorated by the development of corner separation. To ensure an efficient and safe operation of high-load compressors, the pressure distribution and secondary flow on suction surface and end wall can be commonly regulated by means of 3D blading or end wall profiling, so as to suppress the corner separation and the improve the compressor performance. However, due to the complexity of corner separation and its sensitivity to local secondary flow and pressure distribution, the control mechanism of corner separation has not been fully revealed in present, especially when considering the multi-condition perform and the interaction of flow between stages. To improve the multi-condition performance and the interaction between compressor stages, this research try to reveal the complex, nonlinear effect of near wall secondary flow on the development of corner separation, base on CFD and experimental study of a high-load compressor cascade. A new reverse design method of suction surface and the end wall profiling will be further carried out based on the correction of near-wall secondary flow. This study will provide a new flow control technology reserve for improving the performance in the high-load compressor and make a beneficial attempt to resolve the end wall problem in high-load compressors.

高性能航空发动机要求压气机具有更高的级负荷。但高负荷压气机端区问题突出，强烈的角区分离易对整机效率与稳定裕度造成严重影响。为保障高负荷压气机的高效、安全工作，常采用叶片或端壁造型一类手段对吸力面、端面的压力分布与二次流运动进行调控，从而控制角区分离并获得压气机性能的提升。然而，由于角区分离自身成因复杂，对局部流动与压力分布敏感，现有研究对于角区分离的控制机理尚不能完全掌握，特别是难以兼顾多工况下压气机性能与级间作用问题。本项目将考虑以高负荷压气机叶栅中发生的角区分离为研究对象，兼顾多工况性能与级间作用，从系统角度揭示近壁面二次流对角区分离复杂、非线性的控制机理的研究，并在此基础上发展基于近壁面二次流修正算法的吸力面-端面联合造型反向设计方法。本项目研究成果可为高负荷压气机性能提升提供技术支持，并为突破高负荷压气机的端区流动控制难题进行有益尝试。

高负荷轴流压气机中，端部二次流动易引发严重的角区分离。由此引发的气动损失与流动结构变化，易导致压气机效率与稳定裕度下降，是近年来制约压气机性能改进的气动难题之一。如何合理优化端部二次流结构，控制流动分离与气动损失，成为高负荷压气机设计中面临的主要技术瓶颈。为解决上述问题，本项目研究从被动流动控制技术出发，结合数值分析与实验验证，发展出基于吸力面叶身-端面联合造型控制角区分离的新流动控制技术。. 研究首先由典型高负荷轴流压气机提取其端区截面基元构造叶栅模型，在经实验校准数值方法后，在多工况下对端区二次流场及角区分离流动进行初步分析，并据此定义与之流动特征相关联的气动流场量化指标；. 之后，分别依靠两种建模思路，建立端壁-角区-吸力面一体化造型模型，并通过扰动造型参数批量生成造型后叶栅几何、绘制叶栅网格、开展数值计算并最终获取流场信息，生成与流动控制相关的端壁造型数据库。借助优化设计，相关性分析、自反馈神经网络等数据挖掘工具，归纳得到，端壁区及角区在设计点和近失速点对角区分离的流动控制规律，并借助数值工具进行结果验证。. 在完成上述两步研究之后，用实验方法验证吸力面-端壁造型对角区分离的控制效果。发展端区流动简化模型，基于此模型与前述所获端区流动控制经验，从反设计的思路发展了端壁-吸力面一体化造型方法，按照此方进行端区流动控制，实验验证其对全局损失达到有效控制。