We have carried out axisymmetric numerical simulations of a spatiallydeveloping hypersonic boundary layer over a sharp 7$^{\circ{}}$-half-angle coneat $M_\infty=7.5$ inspired by the experimental investigations by Wagner (2015).Simulations are first performed with impermeable (or solid) walls with aone-time broadband pulse excitation applied upstream to determine the mostconvectively-amplified frequencies resulting in the range 260kHz -- 400kHz,consistent with experimental observations of second-mode instability waves.Subsequently, we introduce harmonic disturbances via continuous periodicsuction and blowing at 270kHz and 350kHz. For each of these forcing frequenciescomplex impedance boundary conditions (IBC), modeling the acoustic response oftwo different carbon/carbon (C/C) ultrasonically absorptive porous surfaces,are applied at the wall. The IBCs are derived as an output of a pore-scaleaeroacoustic analysis -- the inverse Helmholtz Solver (iHS) -- which is able toreturn the broadband real and imaginary components of the surface-averagedimpedance. The introduction of the IBCs in all cases leads to a significantattenuation of the harmonically-forced second-mode wave. In particular, weobserve a higher attenuation rate of the introduced waves with frequency of350kHz in comparison with 270kHz, and, along with the iHS impedance results, weestablish that the C/C surfaces absorb acoustic energy more effectively athigher frequencies.
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