• Title/Summary/Keyword: Upstream Unstabilization

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Influence of Upstream State on the Interacting Turbulent Boundary Layer (相互作용하는 亂流 境界層에 대한 上流狀態의 影響)

  • 이덕봉
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.3
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    • pp.277-284
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    • 1986
  • A numerical procedure (integral method) for calculating the interacting turbulent boundary layer is set up. With this method, some free interactions with various upstream conditions are simulated in order to investigate the influence of upstream state on the interacting turbulent boundary layer. The results obtained by this numerical simulation can be summarized as follows; Free interaction of upstream unstabilized (or separated) turbulent boundary layer is subcritical regardless of its external Mach number, while free interaction of upstream stabilized turbulent boundary layer has two different characteristics (subcritical, supercritical) according to the external Mach number.

Interaction Between an Unstabilized Turbulent Boundary Layer and an Incident Oblique Shock Wave (不安定化된 亂流境界層 과 斜角入射衝擊波 와의 相互作용)

  • 이덕봉
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.2
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    • pp.158-173
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    • 1985
  • An experimental investigation has been made to study the interaction between and incident oblique shock wave and an unstabilized turbulent boundary layer on a solid surface downstream of a porous surface with air injection through the porous surface. The boundary layer upstream of the interaction is unstabilized by the injection and provokes a shock wave which eventually interacts with the unstabilized boundary layer after reflecting from the upper wall of the test section. Three cases having diferent upstream Mach numbers and different shock strengthes are studied. According to the level of the unstabilization, two cases are of attached boundary layers and the other one is of a separated boundary layer. The result shows that the reflected wavey system is composed of the compression wave, expansion wave fan, and recompression wave like the ordinary interaction while the separated boundary layer strengthens the reflected expansion waves. The interactions of the attached boundary layers show a similar tendency of the upstream wall pressure distribution as that of the ordinary interacton but the pressure rise rather decays in the downstream region. In case of the separated boundary layer, the wall pressure continues to rise in the downstream as opposed ot the former cases. This indicates that the interaction region spreads out widely adn the viscous effect of the separated boundary layer smoothens the abrupt pressure increase due to the shock inpingement.