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Journal of Hydrodynamics

, Volume 31, Issue 2, pp 256–265 | Cite as

Hidden flow structures in compressible mixing layer and a quantitative analysis of entrainment based on Lagrangian method

  • Geng Liang
  • Bin Yu
  • Bin ZhangEmail author
  • Hui Xu
  • Hong Liu
Special Column for Symposium on Vortex Identification Methods and Applications (Guest Editor Yu-Ning Zhang)
  • 30 Downloads

Abstract

The compressible mixing layer is an important physical model to describe the mixing enhancement in scramjet combustors. The downstream coherent structures are normally regarded as the main contribution of the entrainment in the compressible mixing layer. In this study, three cases of the compressible mixing layer of convective Mach number Ma = 0.4 are numerically simulated through the Lagrangian coherent structure (LCS) method to show that the entrainment process in the compressible mixing layer is closely related to the upstream hidden structures termed as the “entrainment formation structures”. The entrainment formation structures consist of a series of inclined control bodies that are identical and nested to one another upstream the compressible mixing layer. In combination with the separation of the flow properties of coherent structures, the entrainment characteristics in the compressible mixing layer can be evaluated by the inclined control bodies of the upstream entrainment formation structures in the upper and lower fluids. Furthermore, with the quantitative analysis of the spatial position of the upstream coherent structure, the entrainment ratio is determined. The study of the entrainment formation and its characteristics helps the effective control of the entrainment performance in the compressible mixing layer.

Key words

Compressible mixing layer Lagrangian coherent structure (LCS) finite-time Lyapunov exponent (FTLE) 

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Copyright information

© China Ship Scientific Research Center 2019

Authors and Affiliations

  • Geng Liang
    • 1
  • Bin Yu
    • 1
  • Bin Zhang
    • 1
    Email author
  • Hui Xu
    • 1
  • Hong Liu
    • 1
  1. 1.School of Aeronautics and AstronauticsShanghai Jiao Tong UniversityShanghaiChina

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