高雷诺数下跨声速自然层流短舱优化设计

Transonic natural laminar flow nacelle optimization design at high Reynolds number

为解决高雷诺数下大涵道比发动机自然层流短舱高维优化设计问题,提取短舱3个基准面实现轴对称自然层流优化设计。通过获得较大范围层流区域,从而降低短舱表面摩擦阻力。采用类别形状函数(CST)参数化、γ-Reθt转捩模型和遗传算法建立自然层流(NLF)短舱自动优化流程。表明通过优化短舱基准面建立三维NLF短舱设计方法的可行性。进而通过CATIA二次开发构建三维非轴对称NLF短舱,解决了基准面优化后大量数据点的高效导入和曲面生成问题。针对设计的非轴对称NLF短舱,进行了设计点附近迎角、侧滑角、来流马赫数以及湍流度的转捩敏感性分析。结果表明:跨声速状态下,迎角增大层流范围减小;来流马赫数增大层流范围扩大;侧滑角和湍流度对层流范围影响很小。

To solve the problem of high-dimensional optimization design of laminar flow nacelle with large bypass ratio under high Reynolds number,three datum planes of nacelle were extracted to realize the optimal design of axisymmetric natural laminar flow.A wide range of laminar flow was obtained to reduce the surface friction resistance of the nacelle. An optimization system for the natural laminar flow(NLF)nacelle was established in combination with class and shape transformation(CST) parameterization, γ-Reθt transition model and the genetic algorithm. It showed the feasibility of establishing a three-dimensional NLF nacelle design method by optimizing the nacelle datum plane.Then,a three-dimensional non-axisymmetric NLF nacelle was constructed through the secondary development of CATIA, which solved the problem of efficiently importing a large number of data points and surface generation after the datum plane optimization.For the designed three-dimensional non-axisymmetric NLF nacelle,a transition sensitivity analysis of the angle of attack,sideslip angle,incoming Mach number,and turbulence intensity near the design point was conducted. The results showed that: under the condition of transonic speed,the laminar flow range decreased with the increase of the angle of attack;the laminar flow range increased with the increase of incoming Mach number;the sideslip angle and turbulence intensity had little effect on the laminar flow range.