Acta Mechanica Sinica

, Volume 6, Issue 4, pp 296–302 | Cite as

Nature of the surface heart transfer fluctuation in a hypersonic separated turbulent flow

  • Wang Shifen
  • Li Qingquan


This paper presents the results of an experimental study of the unsteady nature of a hypersonic separated turbulent flow. The nomimal test conditions were a freestream Mach number of 7.8 and a unit Reynolds number of 3.5×107/m. The separated flow was generated using finite span forward facing steps. An array of flush mounted high spatial resolution and fast response platinum film resistance thermometers was used to make multi-channel measurements of the fluctuating surface heat trtansfer within the separated flow. Conditional sampling analysis of the signals shows that the root of separation shock wave consists of a series of compression wave extending over a streamwise length about one half of the incoming boundary layer thickness. The compression waves converge into a single leading shock beyond the boundary layer. The shock structure is unsteady and undergoes large-scale motion in the streamwise direction. The length scale of the motion is about 22 percent of the upstream influence length of the separation shock wave. There exists a wide band of frequency of oscillations of the shock system. Most of the frequencies are in the range of 1–3 kHz. The heat transfer fluctuates intermittently between the undisturbed level and the disturbed level within the range of motion of the separation shock wave. This intermittent phenomenon is considered as the consequence of the large-scale shock system oscillations. Downstream of the range of shock wave motion there is a separated region where the flow experiences continuous compression and no intermittency phenomenon is observed.

Key Words

hypersonic separated turbulent flow shock wave and turbulent boundary layer interaction heat transfer fluctuation unsteady shock structure 



instantaneous heat transfer rate


standard deviation of fluctuating heat transfer signal


intermittency function


intermittency factor


period of the shock wave oscillation


frequency of the shock wave oscillation


probability density function of the periods (or the frequencies) of the shock wave oscillation


upstream influence length of the unsteady separation shock wave, defined by the distance between the upstream limit of shock wave motion and the corner line of forward facing step


time length of each record


incoming boundary layer thickness


distance from the corner line of forward facing step along the upstream central line of the flat plate


measured at the wall


undisturbed flat plate value


downstream zone of shock wave


upstream zone of shock wave


bar over the symbol denotes time average


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Copyright information

© Chinese Society of Theoretical and Applied Mechanics 1990

Authors and Affiliations

  • Wang Shifen
    • 1
  • Li Qingquan
    • 1
  1. 1.Institute of MechanicsChinese Academy of SciencesChina

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