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CFD based unsteady aerodynamic modeling for rotor aeroelastic analysis.

机译：基于CFD的非定常气动模型用于转子气动弹性分析。

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摘要

A Computational Fluid Dynamics (CFD) analysis is developed for 3-D rotor unsteady aerodynamic load prediction. It is then coupled to a rotor structural analysis for predicting aeroelastic blade response, airloads and vibration. The CFD analysis accounts for the elastic deformations using a dynamically deforming mesh system. All the rotor blades are assumed to be identical, therefore to reduce the computational complexity the CFD calculations are performed for a single blade. This accounts for the near wake flow field. But the far wake effects because of the trailed tip vortices from all the blades have to be included separately. This is achieved by the use of the field velocity approach, which is a method for modeling unsteady flows via apparent grid movement. In this method, the induced velocity field caused by the trailed vortex wake is included by modifying the grid time metrics.; The CFD method developed is systematically validated for a range of problems starting from simple 2-D model problems to full scale forward flight cases. The CFD analysis shows significant improvements in airloads prediction compared to a table lookup based lifting-line analysis. The CFD analysis is then used to investigate the fundamental mechanisms of rotor vibration. It is found that both the normal forces and pitching moments are dominated by three dimensional aerodynamic effects. The curvature introduced by the blade elasticity appears to play a key role in the generation of the vibratory harmonics in airloads. The pitching moments near the blade tip (85% outboard) are significantly affected by transonic tip relief effects. The fundamental understanding of rotor vibrations gained from this study is then used to develop generic corrections for improving the accuracy of a lifting line analysis.; Finally the CFD analysis developed is coupled with an advanced comprehensive rotor aeroelastic analysis. The coupling procedure is formulated in a way such that there is an exchange of information between the structural model and CFD model every rotor revolution. The coupled CFD/structure scheme is found to considerably improve the prediction of rotor vibratory airloads compared to the baseline rotor aeroelastic analysis which uses a lifting line based aerodynamic model.
机译：计算流体动力学（CFD）分析针对3-D转子非稳态气动载荷预测进行了开发。然后将其耦合到转子结构分析中，以预测气动叶片的响应，空气载荷和振动。 CFD分析使用动态变形网格系统考虑了弹性变形。假定所有转子叶片都是相同的，因此，为降低计算复杂度，对单个叶片执行CFD计算。这说明了近尾流场。但是由于来自所有叶片的尾部涡流而导致的远尾效应必须单独包括在内。这是通过使用场速度方法实现的，该方法是一种通过视在网格运动来对非恒定流建模的方法。在该方法中，通过修改网格时间度量来包括由尾涡涡流引起的感应速度场。从简单的二维模型问题到全面的前向飞行案例，已开发的CFD方法已针对一系列问题进行了系统验证。与基于表格查找的起重线分析相比，CFD分析显示了在空气负荷预测方面的显着改进。然后，将CFD分析用于研究转子振动的基本机理。发现法向力和俯仰力矩均受三维空气动力学影响。叶片弹性引入的曲率似乎在空载中产生振动谐波中起着关键作用。跨音速叶顶释放效应会显着影响叶片尖端（外侧85％）附近的俯仰力矩。然后，将从这项研究中获得的对转子振动的基本理解用于开发通用校正，以提高提升线分析的准确性。最后，开发的CFD分析与先进的全面转子气动弹性分析相结合。耦合过程的制定方式使得每次转子旋转时，结构模型和CFD模型之间都会交换信息。与使用基于举升线的空气动力学模型的基线转子气动弹性分析相比，CFD /结构耦合方案显着改善了转子振动空气载荷的预测。

著录项

  • 作者

    Sitaraman, Jayanarayanan.;

  • 作者单位

    University of Maryland College Park.;

  • 授予单位 University of Maryland College Park.;
  • 学科 Engineering Aerospace.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 334 p.
  • 总页数 334
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 航空、航天技术的研究与探索;
  • 关键词

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