考虑叶片造型的压气机流动稳定性模型研究进展

PROGRESS IN THE STUDY OF FLOW STABILITY MODEL OF COMPRESSOR CONSIDERING BLADE MODELLING

压气机实际稳定裕度是否达到指标直接决定了发动机是否可以投入使用.目前的压气机气动设计体系中缺乏一种高效、准确的评估失稳边界的工具,导致在设计定型后依然存在实际稳定裕度不足的风险.因此迫切需要发展快速可靠的压气机稳定性预测工具以供设计阶段使用.现代航空压气机叶片的气动设计朝着三维精细化方向发展,如何在设计阶段考虑叶片三维造型的变化对稳定性的影响愈发关键.传统的激盘/半激盘模型难以精细捕捉到三维叶片造型对流动稳定性的影响,而非定常数值模拟方法对计算资源的消耗在压气机设计阶段难以承受.为了在精细考虑叶片造型影响的同时提高计算效率,为气动设计阶段提供稳定性评估工具,本团队首先在2013年提出了叶轮机流动稳定性通用理论,通过分布式叶片力源项建模考虑复杂叶片造型的影响,通过系统特征值描述流动稳定性.继而针对不同的预测目标和应用条件,发展了3种简化模型:子午面模型、流线模型和径向展开模型.其中子午面模型能够准确刻画叶尖间隙、叶片掠和叶片加载方式等关键设计参数对流动稳定性的影响,为设计阶段提供了一种可靠的失稳边界预测工具;流线模型可以快速评估展向各条流线系统的流动稳定性,并定量地给出流动稳定性最为薄弱的区域,从而有针对性地指导叶片扩稳设计;径向展开模型可以快速地预测离心压气机的流动失稳点,定量评估离心压气机流动稳定性.以上模型可以应用于压气机气动设计体系,为设计定型的压气机提供了可靠的稳定性评估方法,为压气机气动/稳定性一体化设计提供了技术储备.

Whether the actual stall margin of the compressor can reach the design target directly determines whether the engine can be put into service.The current system of compressor aerodynamic design lacks an efficient and accurate tool to evaluate the stall margin,which maybe lead to great risk.Therefore,it is urgent to develop a fast and reliable compressor stability prediction tool for use in the design phase.The aerodynamic design of modern aircraft compressors is increasingly oriented towards three-dimensional refinement,and considering the effect of three-dimensional blade shapes on stability during the design phase has become crucial.Traditional excited disk and semi-excited disk models struggle to capture the intricate effects of three-dimensional blade shapes on flow stability,while unsteady numerical simulation methods demand too much computational resource during the compressor design phase.In order to simultaneously enhance the consideration of blade shape effects and improve computational efficiency,providing a stability assessment tool for the aerodynamic design phase,our team initially proposed a general theory for the flow stability of turbomachinery in 2013.This theory incorporates the impact of complex blade shapes through the modeling of distributed blade force sources,and the flow stability is described by system eigenvalues.Subsequently,three simplified models were developed to cater to different prediction objectives and application conditions:the meridional plane model,streamline model,and radial expansion model.Among these,the meridional plane model can accurately characterize the influence of critical design parameters such as blade tip clearance,blade sweep,and blade loading on flow stability,and can offer a reliable tool for predicting instability boundaries during the design phase.The streamline model can rapidly assess the flow stability of various streamline systems in the spanwise direction,and provide quantitative information on the regions of greatest flow instability to guide blade design for stability enhancement.The radial expansion model can rapidly predict the flow instability point of a centrifugal compressor,allowing for a quantitative evaluation of its flow stability.These models find application within the aerodynamic design framework of compressors,furnishing a dependable stability assessment method for finalized compressor designs.Consequently,they constitute a technological foundation for the integration of aerodynamics and stability in compressor design.