基于自由变形技术的混合排气喷管气动优化设计

以内外涵混合排气喷管为研究对象，建立了控制体与喷管网格模型的映射关系，通过控制点运动实现了喷管内、外涵双层壁面与网格同步、大曲率变形，并应用优化拉丁超立方设计（OLDH）方法创建了实验样本点。在此基础上，利用Isight软件驱动网格自由变形(FFD)模块和CFD仿真模块完成了所有样本点计算。结果表明:通过优选设计仿真结果，喷管推力系数提高0.6%，总压损失降低0.6%。对优选造型采用多段线+圆弧的方式进行了几何特征提取，获得的参数化造型与优选造型性能接近，具有一定的工程实用价值。 

Aerodynamic optimization design of mixed exhaust nozzle based on FFD technique

As a mixed exhaust nozzle was taken as the research object, the mapping relation between the arbitrary shape deformation volume and a mixed exhaust nozzle sketch was built. Through movement of the control points, synchronously large curvature deformation of the profiles and grid was realized. Whats more, experimental samples were established with application of the optimal Latin hypercube design (OLHD) method. On this basis, as the free form deformation (FFD) and CFD modules were driven by the Isight software, all the sample points were calculated. According to the simulation results, optimum sketch was selected with 0.6% increase of the thrust coefficient and 0.6% reduction of the total pressure loss. Finally, multi-lines and arcs were adopted to parameterize the optimum sketch with no performance degeneration, which can be used in engineering practice.