The effect of microporous surfaces on the secondary instabilities in a supersonic boundary layer was investigated using linear stability theory and nonlinear parabolized stability equations. The linear stability results indicate that the porous surface significantly enlarges the growth rate of the first mode disturbance and advances the transition. A two-dimensional disturbance is more sensitive to the porous surface than is an oblique disturbance. Nonlinear stability analysis suggested that the two classical secondary instabilities, namely the fundamental and subharmonic resonances, lead to transitions when the disturbance amplitude is high. The subharmonic resonance is stronger than the fundamental resonance. A porous surface enlarges the growth rates of the primary and secondary instabilities and promotes the transition. As the porosity coefficient or pore radius increases, the transition onset position gradually moves upstream. However, the fundamental resonance is more sensitive to the porous wall than is the subharmonic resonance, and the porous surface affects the secondary instabilities in different ways. For the fundamental resonance, the porous surface not only enlarges the amplitude of the primary mode, but also directly destabilizes the fundamental disturbance. These two effects cause the fundamental-type breakdown to occur much earlier. For the subharmonic resonance, the destabilization of the primary mode is dominant, and the subharmonic disturbance is not sensitive to the porous wall boundary conditions.
Secondary Instabilities in Supersonic Boundary Layers over Microporous Surfaces
J. Aerosp. Eng.
Journal of Aerospace Engineering ; 36 , 4
2023-07-01
Article (Journal)
Electronic Resource
English
British Library Conference Proceedings | 2008
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