一种基于浸没边界-大涡模拟的降落伞流固耦合计算方法

Fluid-structure interaction simulation of parachute inflation based on an immersed boundary method and large eddy simulation

  • 摘要: 降落伞充气过程涉及复杂的流固耦合(fluid-structure interaction, FSI)现象,浸没边界(immersed boundary, IB)方法作为一种边界非协调方法,适合处理这种非线性大变形FSI问题。将Mittal等提出的尖锐界面IB方法与大涡模拟(large eddy simulation, LES)相结合(LES/IB),应用于中高雷诺数(Re)降落伞绕流的模拟。在此基础上,结合非线性有限元方法,建立了一种基于适合复杂外形非均匀湍流的动态Vreman亚格子(Vreman subgrid-scale, Vreman SGS)模型的FSI方法,用于模拟降落伞充气过程。最后,通过经典的圆柱绕流算例(Re = 3900)验证所发展的LES/IB方法的准确性。结果表明,LES/IB方法对平均阻力系数(\bar C_D )、后缘点平均背压系数(-\bar C_p,\rm b )和斯特劳哈尔数(St)的计算结果与直接数值模拟、LES和实验结果吻合较好,误差均低于8%。此外,利用发展的Vreman SGS模型对典型的圆伞和十字伞充气过程中的气动性能和结构响应进行了分析,并与Smagorinsky SGS模型进行了对比。结果表明,在降落伞充气呼吸阶段,两者对阻力系数和投影面积的计算结果吻合较好,相对误差均在5%以内,验证了本文FSI方法的可靠性。

     

    Abstract: The inflation process of a parachute involves complex fluid-structure interaction (FSI) phenomena. The immersed boundary (IB) method, as a boundary non-conforming approach, is suitable for addressing such nonlinear large-deformation FSI problems. By integrating the sharp-interface IB method proposed by Mittal et al. with large eddy simulation (LES), the flow around a parachute at medium to high Reynolds numbers (Re) was simulated. On this basis, a nonlinear finite element method was incorporated to develop an FSI approach based on the dynamic Vreman subgrid-scale (Vreman SGS) model, which was suitable for complex geometries and non-uniform turbulence, to simulate the parachute inflation process. Finally, the accuracy of the developed LES/IB method was validated by a classic cylinder flow case (Re = 3900). The results demonstrate that the LES/IB method achieves good agreement with direct numerical simulation (DNS), LES, and experimental data in terms of the mean drag coefficient (\bar C_D ), mean base pressure coefficient at the rear stagnation point (- \bar C_p,\rm b ), and Strouhal number (St), with errors all below 8%. Furthermore, the developed Vreman SGS model was employed to analyze the aerodynamic performance and structural response during the inflation of typical round and cruciform parachutes, and the results were compared with Smagorinsky SGS model. During the breathing phase of parachute inflation, the results of the drag coefficient and projected area calculated by both methods show good agreement, with relative errors within 5%, thereby validating the reliability of the proposed FSI method.

     

/

返回文章
返回