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A computational model to characterize different flow regimes for microscale re-entry satellites.

机译：一种计算模型，用于表征微型再入卫星的不同流态。

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摘要

Atmospheric re-entry vehicles experience different flow regimes during flight due to the change in atmospheric density along the re-entry trajectory. This change in density creates non-equilibrium regions on the order of mean free path, called Knudsen layer. In the design of atmospheric re-entry vehicles, the flux variations near the wall of the re-entry vehicles are of critical importance. Traditional CFD simulations that use Navier-Stokes equations fail to predict the flow in the Knudsen layer. The Direct Simulation Monte Carlo (DSMC) method is accurate for all flow regimes, and correctly models the Knudsen layer but is computationally expensive. The computational cost increases as the number of molecules simulated increases. The areas where the rarefaction effects begin to dominate can be quantified by a Knudsen breakdown parameter (Kn). Traditional CFD can be improved with the use of slip boundary conditions in regions where the Knudsen breakdown parameter predicts the failure of continuum regime. In this thesis, a computational model has been developed to extend the validity of the continuum formulation with slip boundary conditions. The model uses the no-slip boundary conditions for continuum regime (Kn<0.01), and Maxwell-Smoluchowski slip boundary conditions for slip regime (Kn<0.1) in the free stream atmospheric properties. The results demonstrate the validity of the unified model in continuum and slip regime. For specific Knudsen number, flow predictions were validated against results from DSMC. The flow results matched within 10%.
机译：大气再入飞行器在飞行过程中由于沿再入轨迹的大气密度变化而经历不同的流动状态。密度的这种变化会在平均自由程的数量级上创建非平衡区域，称为Knudsen层。在大气再入飞行器的设计中，再入飞行器壁附近的通量变化至关重要。使用Navier-Stokes方程的传统CFD模拟无法预测Knudsen层中的流动。直接模拟蒙特卡洛（DSMC）方法适用于所有流态，并且可以对Knudsen层进行正确建模，但计算量大。随着模拟分子数量的增加，计算成本也随之增加。稀疏效应开始占主导地位的区域可以通过Knudsen击穿参数（Kn）进行量化。传统的CFD可以通过在Knudsen分解参数预测连续介质失效的区域中使用滑动边界条件来改善。在本文中，开发了一个计算模型以扩展具有滑动边界条件的连续体公式的有效性。该模型在连续流大气特性中使用无滑移边界条件作为连续状态（Kn <0.01），将麦克斯韦-斯莫卢霍夫斯基滑移边界条件用于滑动状态（Kn <0.1）。结果证明了该统一模型在连续和滑动状态下的有效性。对于特定的努森数，根据DSMC的结果验证了流量预测。流量结果匹配在10％以内。

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  • 作者

    Thiruvenkadam, Sudharsan.;

  • 作者单位

    The University of Texas at Arlington.;

  • 授予单位 The University of Texas at Arlington.;
  • 学科 Engineering Aerospace.;Engineering Mechanical.
  • 学位 M.Engr.
  • 年度 2013
  • 页码 83 p.
  • 总页数 83
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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