面向气动设计及加工的叶片一体化建模理论研究

Blades are criticial components of aero engine. The design and processing quality of blades directly affects engine performance. Blade model is the carrier of aerodynamic design requirements, as well as the source of latter manufacturing and test procedures, which makes it the crucial part in the blade design system. Most of existing blade geometric representation methods is lack of combination with aerodynamic design. Before blade machining, the machining personnels have to construct blade surface using the design data. In this process, the initial blade model may change. Due to the aerodynamic design has been completed, the effects of blade’ aerodynamic performance caused by derviation of blade shape is unpredictable. Based on analysis of blade aerodynamic design and the requirement for blade machining, this project proposes a profiles generating method based on camber line generated imitating flow angle change. The camber line can reflect the change tendency of the gas flow channel. Considering the drawback of the planar, cylindrical and conical flow surface assumptions, a universal blade’ profiles geometric design method on arbitrary rotary flow surfaces is investigated. At the same time , to satisfy the machining requirement, the strategy smoothing blade surface will be studied. After the smoothness, the blade can be used to machine directly, which avoid the pretreatment of blade surface before machining. The establishment of the theory will be helpful for the improvement of blade design quality, shortening the development cycle and reducing costs.

叶片是航空发动机的关键零部件，其设计与加工质量直接影响到整机性能。叶片模型是气动设计的具体载体，是制造、检测等后续环节的依据和数据源头，在叶片的整个设计体系中占有重要地位。现有的叶片表示方法与气动设计数据结合不足，叶片模型与气动设计需求不完全一致，增加了数值验算的次数。此外，叶片加工前需要对设计数据进行重新拟合以生成叶片曲面，由于这个阶段气动设计已经完成，叶片模型误差对气动性能影响不可预知。本项目结合对叶片气动设计过程的分析和加工对叶片曲面模型的要求，拟仿气流前进变化的规律，指定中弧线弯角的分布，生成中弧线，使得生成的叶型直观的反映出气流流道的变化趋势；针对平、圆柱和圆锥流面假设的不足，研究将几何叶型设计在任意回转流面内；同时在叶片曲面生成阶段考虑加工需求，使得最终生成的曲面模型避免更改直接应用于加工，避免加工前对叶片曲面的处理。该叶片建模理论的建立有助于提高叶片的设计质量，缩短研发周期.

本项目围绕面向气动设计及加工的叶片几何建模问题进行研究，首先针对二维叶型的设计问题，从直接控制叶型沿流道变化规律的角度出发，开发了基于弯角变化规律中弧线的二维叶型设计方法，并采用分段技术提高了设计灵活性，该方法拥有广阔的造型空间和良好的易用性，能够用同一种方法完成亚音、跨音和超音多种类叶型的设计；其次针对二维叶型向三维流面积叠的设计问题，提出了基于随体坐标系的任意回转流面内叶型设计方法，相对于平、圆柱和圆锥流面而言，任意回转流面更贴近于流面假设；给出了叶片曲面的光顺方法，输出的模型可直接应用于加工。开了一套叶片几何设计软件，包含数据输入，建模和多种类数据输出模块，所开发的软件已经在国内相关院所进行了部分应用。