Applied Mathematics and Mechanics (English Edition) ›› 2016, Vol. 37 ›› Issue (9): 1219-1230.doi: https://doi.org/10.1007/s10483-016-2125-6

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Effect of wall-cooling on Mack-mode instability in high speed flat-plate boundary layers

Shaolong ZHANG, Jianxin LIU, Jisheng LUO   

  1. Department of Mechanics, Tianjin University, Tianjin 300072, China
  • Received:2015-12-04 Revised:2016-03-01 Online:2016-09-01 Published:2016-09-01
  • Contact: Shaolong ZHANG E-mail:shookware@tju.edu.cn
  • Supported by:

    Project supported by the State Key Program of National Natural Science Foundation of China (No. 11332007) and the Young Scientists Fund of the National Natural Science Foundation of China (No. 11402167)

Abstract:

The instability of the Mack mode is destabilized by wall-cooling in a high speed boundary layer. The aim of this paper is to study the mechanism of the wallcooling effect on the Mack mode instability by numerical methods. It is shown that the wall-cooling can destabilize the Mack mode instability, similar to the previous conclusions with the exception that the Mack mode instability can be stabilized by wall-cooling if the wall temperature is extremely low. The reversed wall temperature is related to a freestream condition. If the Mach number increases to a large enough value, e.g., about 7, the reversed wall temperature will tend to be zero. It seems that the Mack mode instability is determined by the region between the boundary layer edge and the critical layer. When the wall temperature decreases, this region becomes wider, and the boundary layer becomes more unstable. Additionally, a relative supersonic unstable mode can be observed when the velocity of the critical layer is less than 1-1/Ma or is cancelled by the wall-cooling effect. These results provide a deeper understanding on the wall-cooling effect in high speed boundary layers.

Key words: wall-cooling, stability, high speed boundary layer, Mack mode instability

2010 MSC Number: 

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